More particularly there is disclosed a method for processing food products on a production line and a method for sanitizing raw food products on a production line.
INTRODUCTION/BACKGROUND
It is widely reported that pathogenic contamination of food is a human health hazard in every nation, frequently resulting in human illness, death and economic losses.
Certain highly consumed food products are identified as having a higher than normal risk of harbouring pathogens, such as protein products for example chicken, turkey, pork or beef; and seafood products such as tilapia, swai, salmon or tuna, and produce products for example cantaloupes, broccoli or sprouts; and nuts for example pistachios or almonds and other foods such as cheese or eggs.

Pre-harvest controls are designed as preventative measures to minimize the risk of contamination but pathogens are ubiquitous in the environment and reside in the intestinal track of animals for example chicken, turkey, pork, or cattle which can be transferred during slaughter e.g. by exudate fluid, blood, saliva, mucus, and lymph fluid. Once in the processing facility, microorganisms can detach from the host to cause cross contamination through direct contact with other products, manipulation via mechanics or human workers, cutting equipment, conveyor belts, wash dip tanks, food bins and packaging.

Microbial interventions employed during processing such as steam, high pressure processing, irradiation, ozone, UV, and chemicals are commonly used during food processing to kill microorganisms on food product and food contact surfaces. In many countries food products are bathed and/or sprayed with antimicrobial chemicals to reduce contamination.

Current methods and procedures for many of these methods fail to reduce the microbe burden on food products sufficiently.

As a result, food recalls, food safety alerts and foodborne illness outbreaks are a common occurrence. According to the U.S. Center for Disease Control there are over 48 million cases of food borne illnesses each year in the United States alone, causing 128,000 hospitalizations which claim 3,000 lives each year in the U.S.

Technological improvements for food processing that improve efficacy over existing methods are needed to further reduce the risk of human illness and death, and diminish the economic impact.

RELATED PRIOR ART

US 2014/322407 discloses a composition comprising hydrogen peroxide as an oxidizing agent and a method for sanitizing a food article comprising the steps of: preparing a use solution by diluting the composition with an aqueous diluent, contacting the use solution with the food article; and allowing sufficient contact time to sanitize the article; and optionally rinsing the article. The composition is applied to the article by spraying or by immersing the article in the solution.

As mentioned in EP 2,478,780 A1 such an antimicrobial composition can be applied with electrostatically accelerated spray.

US 2006/198798-A discloses a peroxygen antimicrobial composition comprising an amine oxide and peroxygen compound. It is claimed that the combination of the two components produces an effective antimicrobial composition, providing a more potent biocide than can be obtained by using these compounds separately. Other components can be added to the composition such as peracetic acid, acetic acid, hydrotrope coupling agents, etc. The composition can be used to sanitize various surfaces such as hard surfaces found in food processing, food service and health care industries.

The peroxygen compound peracetic acid (a.k.a.PAA) is a stronger oxidizer than hydrogen peroxide therefore giving increased efficacy as an antimicrobial.

WO 93/13674-A1 describes a process for exterminating microorganisms residing in a food products in gaseous, liquid and/or pasty form such as milk or milk products. However, the process and the equipment for carrying out the process requires direct contact between a transducer and a the food product, which is not always possible e.g. for food products such as vegetables, nuts, fish and meat, in solid form.

US 2007/059410-A1 relates to cold sterilization and conservation of fruits and vegetables, agricultural and horticultural products, and food stuff with the aid and simultaneous use of different means such as vacuum, ozone, oxygen, carbon-dioxide, argon and UV-C light and ultrasound. However, the embodiments described may require excessive processing time, which is unacceptable connection with commercial food production lines.

Lillard H S: "Decontamination of poultry skin by sonication ..." describes that present production practices do not result in Salmonella and Campylobacter free birds and gives an overview of different treatments of food products using ultrasound, sonication, described in the scientific literature. Among other things, it is reported that "There is a paucity of literature on the application of ultrasonics to solid foods such as poultry. It is mentioned that Sams and Feria (1991 ) exposed pre- and post-chill broiler drumsticks submerged in deionized water to 47 kHz in an ultrasonic cleaning tank. Sonication was for 15 or 30 min at 25 or 40°C and for shorter intervals (0.5, 2, and 3.5 min) in the presence of lactic acid, with pH adjusted to 2 or 4. However, the embodiments referred to appear to require excessive processing time, which is unacceptable connection with commercial food production lines. Also there appear to be a risk of cross-contamination due to the use of tanks.

US 2004/191374 describes a multi-stage system and method for pasteurizing food products that includes a first processing unit configured to receive the food product and apply an amount of non-thermal energy treatment to the food product which is effective to inactivate one or more key enzymes. A second, subsequent, processing unit is configured to receive the food product from the first processing unit and reduces the population of potentially harmful microorganisms by applying thermal pasteurization. The food product may be tomato paste. Also, the embodiments described therein may require excessive processing time, which is unacceptable connection with commercial food production lines.

DE 39 34 500 A1 describes equipment for sterilizing foodstuff such as spices and dried fruits wherein sterilizing is carried out by both microwaves and ultrasound treatment. The equipment comprises a conveyor belt running through chambers with a microwave generator and a conveyor belt for the foodstuffs. The food conveyor can itself act as an ultrasonic source or can be coupled to a separate source. The equipment comprises a tempering chamber, a moistening chamber, a microwave and ultrasound treatment chamber, and a cooling chamber. A steam inlet is provided for the purpose of adding moist to pepper grains in the microwave and ultrasound treatment chamber. Thus, a wealth of treatments are described, but their efficacy at processing speeds required for commercial food processing lines appear to be below common specifications.

Thus, there is a need for food processing methods applying antimicrobial treatments to food products in solid form with an efficacy useful at processing speeds such as those at commercial food processing lines.

SUMMARY

It is observed that when a food product is exposed to at least two consecutive antimicrobial treatments comprising a second antimicrobial treatment following a first antimicrobial treatment, wherein the first

antimicrobial treatment comprises exposing the food product to heat to elevate its surface temperature, the efficacy of the second antimicrobial treatment is improved over the efficacy of the second antimicrobial treatment when taken alone. There is thus provided:

A method for sanitizing food products on a production line, comprising:

- conveying food products through a first processing enclosure and onwards through a second processing enclosure;

- generating a first processing atmosphere within the first processing enclosure by supplying a flow of gas, with a gas temperature above 70 degrees Celsius, to the first processing enclosure, wherein at least a portion of the surface of a food product is exposed, while travelling through the first processing enclosure, to a first processing temperature which is above about 60 degrees Celsius; and

- inside the second processing enclosure, delivering an antimicrobial treatment to the food products when they travel through the second

processing enclosure.

Consequently, a food product is exposed to at least two consecutive antimicrobial treatments, wherein the first antimicrobial treatment comprises exposing the food product to heat to elevate its surface temperature, the efficacy of the second antimicrobial treatment is improved over the efficacy of the second antimicrobial treatment when taken alone.

One reason for this improved efficacy may be that microbes are excessively stressed or stunted by the treatment with heat so that they are more vulnerable when the consecutively following antimicrobial treatment begins. Thus a population of microbes on a portion of the surface of the food product is more effectively killed by the second treatment when following the first treatment.

Thus, the antimicrobial treatment delivered in the second processing enclosure more easily kills those microbes that are stunted and not killed by the processing in the first processing enclosure.

As will be set out in greater below, in some embodiments the second antimicrobial treatment is selected to comprise one or more of: antimicrobial treatment using an antimicrobial agent that is sprayed towards the food product, antimicrobial treatment by rapid chilling of the food product to achieve a surface temperature of at least some portions of a surface of a food product below about 0 degrees Celsius and antimicrobial treatment by exposing the food product to a modified atmosphere.

It should be noted that, the effect of a population of microbes being stunted on a portion of the surface of a food product may remain for a significant period of time after surface temperature of the portion of the food product has reverted to a temperature at or below a temperature of the portion of the food product when it entered the first processing enclosure for heat treatment. This prolonged effect has a synergistic effect with at least the antimicrobial treatment using an antimicrobial agent that is sprayed towards the food product and the antimicrobial treatment by exposing the food product to a modified atmosphere.

The production line can be configured for processing one or more of various types of food products e.g. food products in solid form such as but not limited to: meat e.g. poultry such as chicken, turkey, pheasant, duck, and goose; or beef, veal, pork, lamb, mutton, rabbit, and venison; or seafood such as fish and shellfish; or fruit, berries, vegetables, nuts, and cheeses.

It may be observed that the metabolism of bacteria on said portion of the food product is lowered or arrested during treatment in the first processing enclosure, and wherein the food products are exposed to the treatment in the second processing enclosure before metabolism of bacteria on said portion of the food product has regained a level of metabolism which was measurable when the food product entered the first processing enclosure.

There is an inherent weakness with many food grade antimicrobial agents becoming unstable and degrading before being delivered on the surface of the food product when their temperature deliberately or due to an uncontrolled temperature exposure exceeds room temperature.

However, it appears that at the point in time when an antimicrobial agent becomes unstable an additional or enhanced antimicrobial effect is activated if the microbial organisms are exposed to the antimicrobial agent at that point in time when the antimicrobial agent becomes unstable meaning more reactive.

The Arrhenius equation establishes that chemical reactions occur more rapidly at higher temperatures. The reason for this is the thermal energy relates direction to motion at the molecular level. As the temperature rises, molecules move faster and collide more vigorously, greatly increasing the likelihood of bond cleavages and reformation. The resulting equation is defined as:

k = A e -Ea/(RT)

Wherein k is the rate coefficient, A is a constant, Ea is the activation energy, R is the universal gas constant (8.314 J K"1 mol"1), and T is the temperature (in kelvin). At first, k increases exponentially with increasing temperature and then it levels off as it approaches a limit.

This insight is explored in aspects of the method when delivering an antimicrobial treatment to the food products when they travel through the second processing enclosure comprises delivering a spray of an antimicrobial agent towards the food products that travels through the second processing enclosure.

Delivering the antimicrobial agent by spraying it onto the surface of the food product instead of immersing the food product into a tank holding the antimicrobial agent, has at least the advantage that the surface of the food product, which is relatively warm, is not exposed to the cooling impact of the considerable specific heat capacity of the antimicrobial agent in the tank, which is relatively cold to maintain the antimicrobial agent in a stable condition, at least when the antimicrobial agent is an oxidiser. The cooling impact of the antimicrobial agent when sprayed and taking the form of droplets in a mist is much lower than the cooling impact caused by the considerable specific heat capacity of the antimicrobial agent when contained in the tank.

It would generally not be an option, due to stability considerations, to keep the antimicrobial agent in the tank at a temperature about or exceeding the surface temperature of the food product which is deliberately elevated by the processing in the first processing enclosure. Thus, immersion into a tank would detract from the sanitising efficacy obtainable by spraying.

In some embodiments the antimicrobial agent is a food grade antimicrobial chemical agent. In some aspects the antimicrobial agent is selected from the chemical agents allowed for food treatment by the U.S. Code of Federal Regulations or an FDA Food Contract Notification (FCN) or other pertinent regulatory bodies with oversight in the geographical location the method is executed.

As examples:

United States Department of Agriculture Food Safety and Inspection Service provides a list of "safe and suitable ingredients used in the production of meat, poultry, and egg products". The permitted agents are listed in a directive to food processors - 7120.1 rev 29 issued 9/9/2015.

Code of Federal Regulations Title 21 Food and Drugs Chapter 1 food and drug administration department of health and human services subchapter B

food for human consumption part 173 secondary direct food additives permitted in food for human consumption subpart D specific usages additives (e.g. part 173.370 Peroxyacids).

Additionally, those items listed with the Inventory of Effective Food Contact Substance Notifications (FCN) available at:

http://www.accessdata.fda.gov/scripts/fdcc/?set=fcn

An example is FCN 1389 awarded to Alex C Fergusson LLC (AFCO) that provides regulated concentrations that can be used on meat, poultry, seafood and produce during processing.

Other food grade agents are listed under GRAS notices under U.S. Food and Drug Administration for example GRN No. 435 Preparation consisting of six bacterial monophage specific to Salmonella enterica as an antimicrobial in certain poultry products, fish, shellfish, and fresh and processed fruits and vegetables at 107 plague forming units per gram of food.

(http://www.accessdata.fda.gov/scripts/fdcc/?set=GRASNotices&id=435)

In some aspects the antimicrobial agent is an oxygen-based disinfectant, such as a peroxygen solution.

Typically, antimicrobial chemical agents and especially oxygen-based disinfectants such as a peroxygen compound should be kept at relatively low temperatures to maintain their antimicrobial effect. Therefore, on the one hand, excessive cooling of the food product may occur if dipping or submerging of the food products into a bath of an antimicrobial chemical agent is used as an alternative to spraying with the antimicrobial chemical agent. On the other hand, keeping the antimicrobial chemical agent at a higher temperature and applying dipping or submerging, may degrade shelf life of the food product due to the risk of (thorough) heating and also inhibits ability to maintain constant concentrations of antimicrobial agents delivered in solution.

Consequently, the antimicrobial chemical agent can be dispensed at a sufficiently low temperature to avoid unnecessary degradation of its antimicrobial properties when being an airborne spray while enhancing its antimicrobial efficacy when delivered on the surface of the surface heated food product. This is a great advantage since microbes live on the surface of a food product - and especially since microbes live in small pores, folds, chaps, and slits of the surface which by conventional means can be difficult to reach for effectively reducing a population of microbes.

As mentioned above, an effect is that the antimicrobial effect of the antimicrobial agent meeting a remaining population, after processing in the first processing enclosure, of microbes on the surface of the food product is significantly improved because the likelihood of bond cleavages and reformation of molecules of the antimicrobial agent is increased. This is especially true for an oxygen-based disinfectant.

A variety of peroxygens possesses excellent microbial inhibiting activity under controlled conditions and is sometimes used in chemical sterilization. Hydrogen peroxide (H2O2) when put in solution with acetic acid generates a transient molecule named peracetic acid (PAA) that is a high level disinfectant due to the production of highly reactive hydroxyl radical via dissemination of the peroxy bond. The resulting oxidizing agents can denature proteins, disrupt cell wall/ membrane permeability and oxidize sulfhydral and sulfur bonds in proteins, enzymes, and other metabolites. They have an additional advantage of producing decomposition products that are nontoxic and biodegradable (water, oxygen, carbon dioxide).

A peroxide is a compound containing an oxygen-oxygen single bond or the peroxide anion, Ο2-2, The organic peroxides are dominated by the covalent bonds. The oxygen-oxygen chemical bond of peroxide is unstable and easily split into reactive radicals via homolytic cleavage. For this reason, peroxides are found in nature only in small quantities, in water, atmosphere, plants, and animals.

An organic peroxide is defined as R1-O-O-R2, wherein one or both of R1 and R2 contain carbon. The peroxygen bond is the single bond between the two oxygens that can dissociate to create the radicals R1 -O and R2-O.

In some aspects the antimicrobial agent comprises an antimicrobial agent of the biological type, such as salmonella bacteriophages. The salmonella bacteriophages may be provided as a slurry of salmonella bacteriophages, e.g. such as Intralytix product marketed under the name "SalmoFresh".

In some aspects the antimicrobial agent comprises one or more of: peroxygen compound, sodium hypochlorite, chlorine dioxide, hypochlorous acid, hydrogen peroxide, acetic acid, lactic acid, ozone gas in solution, acidified sodium chlorite, potassium hydroxide, sodium hydroxide, citric acid, and a cationic quaternary ammonium compound, such as cetylpridinium chloride.

In some aspects, the surface temperature of the food product is elevated or lowered, while the food product travels through the second processing enclosure, at a rate having a time constant that is relatively short compared to the retention time of the food product in the second processing enclosure. The time constant may be less than 75% of the retention time e.g. less than 50% of the retention time. The time constant may be defined as a 67% temperature level or a 90% temperature level.

In some aspects, delivering an antimicrobial treatment to the food products when they travel through the second processing enclosure comprises a step of performing rapid surface chilling of the food product.

Thereby at least a portion of the surface of the food product is to at least two consecutive treatments, whereby the surface temperature is first rapidly elevated and then immediately after rapidly lowered. Both treatments stress the microbes. Since the second treatment is performed consecutively after the first treatment, microbes are already vulnerable when the second treatment begins. A further stress factor that stunts a population of microbes exposed at least to this dual treatment is the negative and drastic temperature drop from elevated temperatures to low temperatures, say below about 0 °C.

One observation is that the population of microbes on the surface will be stunted and brought into a recovery phase since they are heavily stressed in the first processing enclosure; then by applying the growth-inhibiting treatment the microbes remains under stress thus increasing the likelihood that the population will rather be further stunted than recover.

In some aspects one or more of the chilling, cooling and freezing is performed to obtain thoroughly chilling, cooling or freezing, whereby both surface temperature and a core temperature of the food product is lowered.

In some embodiments one or more of rapid chilling, cooling and freezing is performed. The applied rapid chilling, cooling or freezing is applied to lower at least a portion of the surface temperature of a food product to about 0 °C or below 0 °C within about 1 -2 minutes or faster.

In some aspects the processing in the first processing enclosure is applied to food products arriving with a surface temperature below 60°C whereby heat energy is transferred from the gas to the surface of the food product via a gas-to-solid heat transfer transition, where 'solid' refers to the surface of the food product, which is not a food product on gaseous, liquid or paste form. The food product may however have a 'soft', 'medium' or 'hard' surface.

The gas is discharged from an outlet, which may be a sound generator as described below, without contact between the outlet and the food product.

By the processing applied in the first processing enclosure, a surface temperature of a food product is elevated from a first surface temperature

measured at a point in time when the food product enters the first processing enclosure to a second surface temperature measured at a point in time when the food product leaves the first processing enclosure.

In some embodiments the food product is conveyed to enter the second processing enclosure wherein rapid cooling, chilling or freezing takes place before the surface temperature of at least a portion of the food product falls below the first surface temperature. Thereby a population of microbes on at least a portion of the surface of the food product is exposed firstly to an elevated temperature which increases the likelihood that the population is killed or stunted, and then rapidly thereafter the remaining portion of the population including those stunted is exposed to a low temperature which again, and shortly after the exposure to the elevated temperature, increases the likelihood that the remaining portion of the population is killed. By such a two-phase stress-treatment of the microbes efficacy of the sanitizing is improved over any one of the treatments.

As mentioned above, by firstly exposing a food product to the first processing atmosphere, wherein a first microbe-weakening treatment takes place, and then, secondly, exposing the food product to the second processing atmosphere, wherein a second microbe-weakening treatment takes place, it is observed that a population of microbes on the surface of the food product are more effectively killed than any one of the microbe-weakening treatments.

In some aspects rapid surface chilling is performed by discharging a gas, with a gas temperature below 0 °C, inside the second processing enclosure at a sufficient flow rate to cool the surface temperature of at least a portion of the food product to a temperature below about 0 °C within less than about one minute.

In some embodiments, rapid surface chilling is performed by discharging one or more of cold air, an inert gas, liquid Nitrogen, and Carbon Dioxide inside the second processing enclosure as it is known in the art.

In some embodiments, one or both of the flow rate of the gas, the gas temperature, and the time the food product is exposed to the rapid surface chilling treatment is set and/or controlled to obtain a trade-off between obtaining rapid surface chilling and avoiding excessive lowering of a core temperature of the food product.

In some aspects delivering an antimicrobial treatment to the food products when they travel through the second processing enclosure comprises a step of applying a modified atmosphere wherein the volume-percentage of one or both of Nitrogen and Oxygen deviates from 78.08% and 20.95% by more than 1 percentage points.

In some aspects delivering an antimicrobial treatment to the food products when they travel through the second processing enclosure comprises a step of applying a modified atmosphere packaging, MAP.

Thus, when a food product is exposed to at least two antimicrobial treatments, wherein the first antimicrobial treatment comprises exposing the food product to heat to elevate its surface temperature, and wherein the second comprises applying a modified atmosphere, the effect of the treatment by a modified atmosphere is improved over a treatment by a modified atmosphere when taken alone.

As mentioned above, the effect of a population of microbes being stunted on a portion of the surface of a food product may remain for a significant period of time after surface temperature of the portion of the food product has reverted to a temperature at or below a temperature of the portion of the food product when it entered the first processing enclosure for heat treatment. This prolonged effect has a synergistic effect with at least the antimicrobial treatment by exposing the food product to a modified atmosphere.

In some aspects the food products are exposed to the processing atmosphere in the first processing enclosure for a first processing duration; and wherein the first processing duration is in the range of 0.15 to 10 seconds, or in the range of 0.2 to 5 seconds, or less than about 4 seconds.

In some aspects the first processing temperature in the first processing enclosure is in the range of 80 to 95 degrees Celsius. The first processing temperature is measured at the surface of the food product, but at a distance therefrom e.g. at a distance of more than 2 millimetres and less than 5 centimetres.

In some aspects the flow of gas is supplied at a rate of about 15 Kg/hour, 20 Kg/hour, 25 Kg/hour or at a higher rate.

In some aspects a surface temperature of a food product is elevated from a first surface temperature measured at a point in time when the food product enters the first processing enclosure to a second surface temperature measured at a point in time when the food product leaves the first processing enclosure; and wherein the food product is conveyed to enter the second processing enclosure before the surface temperature falls below the first surface temperature.

There are at least two noteworthy effects that are brought about by the above method:

One effect is that a second microbe-weakening treatment of a population of microbes on the surface of the food product is brought into action when a first microbe-weakening treatment of the population of microbes has already significantly stunted the population. Thereby, the first and second microbe-weakening treatments combine synergistic over any one of the treatments.

Another effect is that the antimicrobial effect of the antimicrobial agent meeting a remaining population, after processing in the first processing enclosure, of microbes on the surface of the food product is significantly improved because the likelihood of bond cleavages and reformation of molecules of the antimicrobial agent is increased due to the higher temperature.

In some aspects, the food product is conveyed to enter the second processing enclosure before the surface temperature falls below a threshold level being the first surface temperature plus 10% of the temperature elevation. In some aspects the threshold level is the first surface temperature plus a temperature difference selected from the group of: about 10% of the temperature elevation, about 30% of the temperature elevation, about 50%, about 70% of the temperature elevation, and about 85% of the temperature elevation.

Surface heating of the food products strikes a desired balance between activating the additional or enhanced antimicrobial effect improving efficacy while avoiding the quality degradation or undesired cooking that would follow with thoroughly warming or heating of the food product.

In some aspects the food products are exposed to the processing atmosphere in the first processing enclosure for a first processing duration; and wherein the time it takes a food product from it leaves the first processing enclosure and until it reaches the second processing enclosure is less than about 5 seconds, less than about 2 seconds, or less than about 1 second. However, in general, the time it takes a food product from it leaves the first processing enclosure and until it reaches the second processing enclosure may be longer e.g. up to 20 seconds or 20-40 seconds.

In some aspects the food products are exposed to the first processing atmosphere in the first processing enclosure for a first processing duration, which is sufficiently long to raise the surface temperature of the food product by more than 4 degrees Celsius or more than 10 degrees Celsius.

The processing atmosphere in the first processing enclosure may give the food products a transient exposure to heat that is sufficient to raise the surface temperature of at least a portion of the food products at least 4 degrees Celsius or 10 degrees Celsius.

A raise in surface temperature during treatment in the first processing enclosure may be more than about 10°C, 15°C, 20°C, 30°C, or 40°C. A surface temperature of at least a portion of the food product at the point in time when it leaves the first processing enclosure or immediately thereafter may be up to or even above 50°C, 60°C, or 80°C.

In some aspects the processing atmosphere in the first processing enclosure gives the food products a transient exposure to heat, that is sufficient to raise the surface temperature of at least a portion of the food products at least 4 degrees Celsius or 10 degrees Celsius, while limiting a raise in a core temperature of the food products to a significantly lower temperature than the surface temperature after exposure to the first processing atmosphere.

The speed of the conveyor system, the temperature in the first processing enclosure, and the concentration of the gas in the first processing enclosure are parameters that are set or controlled to achieve a desired surface temperature when the food products leave the first processing enclosure.

In some aspects food products are exposed to the first processing atmosphere in the first processing enclosure for a first processing duration, which is shorter than that required for blanching of the food products at the temperature in the first processing enclosure.

In some aspects the first processing duration, is significantly shorter than that required for blanching of the food products at the temperature in the first processing enclosure.

In some aspects the flow of gas comprises steam supplied to the first processing enclosure at a temperature in the range of about 100 to 140 degrees Celsius or in the range of about 120 to 180 degrees Celsius. The flow of gas, such as steam, is supplied via one or more pipes running from a steam generator to gas outlets, at which the steam is discharged in the first processing enclosure. The temperature of about 100 to 140°C or about 120 to 180°C refers to a temperature of the gas, such as steam, in the pipes. In proximity of the outlets, after being discharged, the gas has a somewhat lower temperature of about 100°C or slightly above or below 100°C.

Herein, steam is water vapour. Steam may comprise water vapour and additives in vaporized form. Vaporized additives in the steam must leave only non-toxic or food grade residues on the food product e.g. when condensed on the surface of the food product.

In some aspects the method comprises a step of applying airborne high intensity and high power acoustic waves to at least a portion of said first processing atmosphere causing it to oscillate substantially at the frequency and substantially with the intensity and power of the acoustic waves.

It has been discovered that the combinational treatment of firstly applying a gas, such as a warm or hot gas, with high intensity sound waves sufficient to disrupt a boundary sub-layer surrounding the food product and then applying an antimicrobial chemical agent, such as peracetic acid, by spraying synergistically activates an improved or additional level of efficacy in combating microorganisms on food products while preserving many desired properties of a food product such as freshness in texture, taste and visual appearance.

The high intensity sound waves are applied in the gas e.g. in connection with discharge of the gas in the first processing enclosure. The high intensity sound waves propagates in the gas, approaching the surface of the food product and disrupting a boundary sub-layer surrounding the food product whereby heat transfer from the gas to the food product takes place faster. In some aspects the processing in the first processing enclosure is applied to food products arriving with a surface temperature below 60°C whereby heat energy is transferred from the gas to the surface of the food product via a gas-to-solid heat transfer transition, where 'solid' refers to the surface of the food product, which is not a food product on gaseous, liquid or paste form. The food product may however have a 'soft', 'medium' or 'hard' surface.

In some aspects said high intensity and high power acoustic waves are ultrasonic acoustic waves. Ultrasonic frequencies may be defined as frequencies in the range about 20 KHz to about 50 KHz.

In some aspects said high intensity and high power acoustic waves are generated by a high intensity and high power acoustic wave generator and has an acoustic sound pressure level at approximately 10 cm from an orifice of said generator selected from the group of:

- at least 120 dB,

- at least 130 dB,

- at least 135 dB,

- at least 140 dB,

- at least 150 dB,

- approximately 130 to approximately 165 dB, and

- approximately 130 to approximately 180 dB.

In some aspects high intensity sound or ultrasound is generated by a sound generator of the Hartmann type generator and wherein the pressurized gas is supplied to the sound generator at a pressure in the range of 1 .5 - 5 atm. The sound generator may be a static siren. A static siren generates sound waves without moving parts, at least without moving parts oscillating at the frequencies of the sound generated by the static siren. Thus static sirens, such as the Hartmann generator, may be very robust and continue to work even at long service intervals in production environments. In some aspects the flow of gas is supplied to each sound generator, which may be a static siren, at a rate of about 15 Kg/hour, 20 Kg/hour, 25 Kg/hour or at a higher rate. The temperature of the gas before and after discharge in the first processing enclosure is mentioned above.

Thereby it is possible to achieve a sound pressure level greater than 130 dB, e.g. 132 dB, 134, dB, 136 dB, and up to the highest possible sound pressure achievable, which is approximately 170-180 db. The pressure may be selected to generate a sound pressure in the range of 130-160 dB, above which there is a saturation of the disruptive effect on the sublaminar layer.

In some aspects the food products being sanitized are selected from one of the following groups: poultry, meat, cold seafood, warm seafood, vegetables, fruit, lettuce, berries, nuts, cereal, and cheese.

In some aspects of processing meat e.g. fresh carcasses the processing atmosphere exposes the surface of the carcasses, while travelling through the first processing enclosure, to a raised temperature in the range of 70-100 degrees Celsius, such as to a temperature in the range of 80-95 degrees Celsius. When received at the first processing enclosure, the surface temperature of the fresh carcasses may be in a range of temperatures depending on the type of carcass; cold water seafood can be received at temperatures just above freezing e.g. with a body temperature in the range of 0.5 to 5 degrees Celsius, freshly slaughtered meat can be received at close to body temperature e.g. with a body temperature in the range of 34 to 40 degrees Celsius, and poultry may have a temperature in the range of 30 to 45 degrees Celsius e.g. 32 to 33 degrees Celsius, when received.

Berries have a fragile structure that is easily damaged when exposed to heat. However, berries may carry serious viruses such as Hepatitis and Norovirus. The efficacy of the claimed method and production line makes it possible to treat the berries during only short amounts of time and thus to preserve structure and flavour.

Berries and produce (fruit and vegetables are exposed to a temperature in the range of 70 to 90 degrees Celsius. When received at the first processing enclosure, the surface temperature of the berries may be in the range of 2-25 degrees Celsius or they may be in a frozen condition e.g. with a temperature in the range of -5 to 0 degrees Celsius, or with a lower temperature e.g. below -15 degrees Celsius, such as about -15 degrees Celsius or with a temperature in the range from -5 to 5 degrees Celsius.

For example in the processing of poultry, the temperature of the treatment reaching the poultry product surface in the second processing enclosure is less than 65 degrees Celsius or less than 60 degrees Celsius. The temperature of the spray on the poultry product can ensure that the poultry product is not substantially altered (cooked) by the temperature of the spray.

There is also provided a production line for processing food products, comprising:

a first processing enclosure and a second processing enclosure;

a conveyor system configured to move a food product through the first processing enclosure and onwards through the second processing

enclosure;

wherein the first processing enclosure is coupled to a gas supply system delivering a flow of gas at a gas temperature above 70 degrees Celsius via an orifice to generate a first processing atmosphere within the first

processing enclosure exposing at least a portion of the surface of the food products, while travelling through the first processing enclosure, to a first processing temperature which is above 60 degrees Celsius;

wherein the second processing enclosure is configured to deliver an antimicrobial treatment to the food products when they travel through the second processing enclosure.

Consequently, since the first processing atmosphere in the first processing enclosure firstly exposes the food product to first microbe-weakening treatment, and then, secondly, the spray of an antimicrobial agent in the second processing enclosure exposes the food product to a second microbe-weakening treatment, it is observed that a population of microbes on the surface of the food product is more effectively killed than any one of the microbe-weakening treatments.

In some aspects one or both of the first processing enclosure and the second processing enclosure is a cabinet or chamber. The cabinets or chambers may be arranged in contact with one another such that the exit way of the first processing enclosure abuts with an entry way of the second processing enclosure. Thereby exposure to external or uncontrolled atmospheres can be minimized.

In some aspects the orifice delivering a flow of gas is comprised by a multitude of orifices coupled to the gas supply system delivering a flow of gas at a raised temperature. Thereby an improved distribution of the processing atmosphere exposing the surface of the food products to a raised temperature is achievable.

In some aspects the second processing enclosure is configured with an atomizing nozzle to deliver a spray of a supply of an antimicrobial chemical agent towards the food products travelling through the second processing enclosure.

In some aspects the antimicrobial agent is an oxygen-based disinfectant, such as a peroxygen solution.

In some aspects the second processing enclosure is configured to perform rapid surface chilling of the food product.

In some aspects rapid surface chilling is performed by discharging a gas, with a gas temperature below 0 °C, inside the second processing enclosure at a sufficient flow rate to cool the surface temperature of at least a portion of the food product to a temperature below about 0 °C within less than about one minute.

In some aspects the second processing enclosure (102) is configured to apply a modified atmosphere wherein the volume-percentage of one or both of Nitrogen and Oxygen deviates from 78.08% and 20.95% by more than 1 percentage points.

In some aspects the second processing enclosure is configured to apply a modified atmosphere packaging, MAP.

In some aspects the production line is configured to expose the food products to the processing atmosphere in the first processing enclosure for a first processing duration; and wherein the first processing duration is in the range of 0.15 to 10 seconds, or in the range of 0.2 to 5 seconds, or less than about 4 seconds.

In some aspects the first processing temperature in the first processing enclosure is in the range of 80 to 95 degrees Celsius.

In some aspects the flow of gas comprises steam supplied to the first processing enclosure (201 ) at a temperature in the range of about 100 to 140 degrees Celsius or in the range of about 120 to 180 degrees Celsius

In some aspects the first processing enclosure is configured to apply airborne high intensity and high power acoustic waves to at least a portion of said first processing atmosphere causing it to oscillate substantially at the frequency and substantially with the intensity and power of the acoustic waves.

In some aspects said high intensity and high power acoustic waves are ultrasonic acoustic waves.

In some aspects said high intensity and high power acoustic waves are generated by a high intensity and high power acoustic wave generator and has an acoustic sound pressure level at approximately 10 cm from an orifice of said generator (100) selected from the group of:

- at least 120 dB,

- at least 130 dB,

- at least 135 dB,

- at least 140 dB,

- at least 150 dB,

- approximately 130 to approximately 165 dB, and

- approximately 130 to approximately 180 dB.

In some aspects high intensity sound or ultrasound is generated by a sound generator of the Hartmann type generator and wherein the pressurized gas is supplied to the sound generator at a pressure in the range of 1 .5 - 5 atm.

In some aspects the production line comprises a first storage tank for storing the antimicrobial agent, a second storage tank containing an antimicrobial agent solution, and a compressor for pressurizing the second storage tank and driving the antimicrobial agent solution towards one or more of the nozzles.

The antimicrobial agent is driven through the one or more nozzles via one or more of a piping system or tubing system or hose system connecting the second tank and the nozzles.

In some aspects the atomizing nozzle is configured to deliver an air assisted induction charged electrostatic spray (AAIC-ES).

In some aspects the production comprises a steam generator delivering pressurized steam to the sound generator. The steam generator may deliver a steam of water to the sound generator which emits the sound waves with discharge of the steam through which the high intensity sound waves propagates towards the surface of the food products at which a sub-laminar layer of surrounding air is disrupted. Thereby the heat transfer to the surface of the food product is accelerated. This allows for fast processing times and less heat damage to the inner structure of the food product. The residue from this treatment is mainly water which can be drained from the first processing enclosure via a drainage.

In some aspects the production comprises a wall separating a first processing volume enclosed by the first processing enclosure and a second processing volume enclosed by the second processing enclosure; wherein the wall has an opening forming a passage through which the conveyor and a food product conveyed thereon can pass.

The wall serves the purpose of restricting inflow of gas from the first processing enclosure to the second processing enclosure. However, since at least the food products have to pass from the first processing enclosure to the second processing enclosures, a limited inflow will take place.

The wall may be multi-layered wall, such as a double layered wall or it may be single-layer wall. The wall may be thermally insulated by a thermally insulating layer.

BRIEF DESCRIPTION OF THE FIGURES

A more detailed description follows below with reference to the drawing, in which:

fig. 1 shows a portion of a production line for processing food products;

fig. 2 shows a first production line for processing food products; and

fig. 3 shows surface temperature, T, of a food product as a function of distance, x, along a production line;

figs. 4a, 4b and 4c show surface temperature, T, of a food product as a function of distance, x, along a production line comprising a first and a second processing enclosure;

fig. 5 shows a portion of a production line for processing food products, wherein the first and second processing enclosure are abutting one another;

fig. 6 shows an exemplary cooling facility;

fig. 7 shows an exemplary chilling facility;

fig. 8 shows a portion of a production line for processing food products comprising a chilling facility located downstream of the heating facility;

fig. 9 shows a portion of a production line for processing food products comprising a modified atmosphere facility;

fig. 10 shows a portion of a production line for processing food products comprising a chilling facility and an antimicrobial agent spraying facility;

fig. 1 1 shows the first processing enclosure with a temperature controller; and

fig. 12 shows the second processing enclosure with a temperature controller.

DETAILED DESCRIPTION

Fig. 1 shows a portion of a production line for processing food products. The portion of the production line is generally designated by reference numeral 100 and comprises a first processing enclosure 101 and a second processing enclosure 102. Food products are generally designated 105 and are shown hanging on hooks 104 suspended from a conveyor 103. However, in some embodiments the conveyor may be configured differently e.g. as a belt conveyor whereon the food products are conveyed; the belt of the conveyor or sections thereof may comprise a mesh whereon the food products are carried. The mesh may be e.g. 70% open mesh which provides access to the surface of the food product and even that portion of the surface of the food product which faces the conveyor belt.

The conveyor 103 moves the food products 105 in a direction which is generally denoted a down-stream direction and at a velocity VCOnveyor- The conveyor 103 is loaded with food products 105 at a location upstream of first processing enclosure 101 and unloaded at a location downstream of the second processing enclosure 102. The conveyor 103 follows a path that enters the first processing enclosure 101 via an entry way 106 and leaves it via an exit way 107; and then enters the second processing enclosure 102 via an entry way 108 and leaves it via an exit way 109. The exit way 107 and the entry way 108 may be connected by a duct 1 10 or take the form of an opening in a common, single- or multilayer, wall that separates the interior volume of first processing enclosure 101 from the interior volume of the second processing enclosure 102. The aperture formed by one or more of the exit way 107, the entry way 108 and the duct 1 10 is, on the one hand, sufficiently large that the conveyor and the food products it carries can pass with a sufficiently large clearance to avoid collision during normal operation of the production line. On the other hand, the size of aperture is limited to limit inflow of gas from the first processing enclosure 101 to the second processing enclosure. The aperture may have a cross-sectional area which is less than a cross-sectional area of the first processing enclosure e.g. less than 75% or less than 50% or less than 25% of the cross-sectional area of the first processing enclosure.

The path that the conveyor 103 follows has a first section which extends inside the first processing enclosure, a second section which extends inside the second processing enclosure and a third section which connects the first and second section.

In some embodiments the first section of the conveyor extends linearly or substantially linearly through the first processing enclosure. Likewise, in some embodiments the second section of the conveyor extends linearly through the second processing enclosure. The first section, the second section and the third section of the conveyor has lengths L1 , L2 and L3,

respectively. The length of the first section may be from about 10 cm up to about 4 meters, e.g. about 1 .5 meters. The length of the second section may be in the range of 1 -3 meters, e.g. about 1 .5 meters.

The length of the third section of the conveyor, extending between the first and the second processing enclosure, may be less than 50 cm, less than 30 cm, less than 15 cm or less than about 10 cm; it may be up to 2 meters, e.g. up to 1 meter. In some aspects, the food product is conveyed to enter the second processing enclosure (102) before the surface temperature of a portion of a food product falls below a threshold level being a first surface temperature plus 10% of the temperature elevation; wherein the first surface temperature is the surface temperature at the portion of the food product when it entered the first processing enclosure or immediately before. In some aspects the threshold level is the first surface temperature plus a temperature difference selected from the group of: about 10% of the temperature elevation, about 30% of the temperature elevation, about 50%, about 70% of the temperature elevation, and about 85% of the temperature elevation.

The sound generators 1 1 1 and 1 12 may be arranged in a pattern e.g. along one or more lines that follows the first section of the path of the conveyor.

The nozzles 1 19 and 120 may be arranged in a pattern e.g. along one or more lines that follows the second section of the path of the conveyor.

In some embodiments the first processing enclosure comprises one sound generator; in other embodiments the first processing enclosure comprises a multitude of sound generators.

In some embodiments the second processing enclosure comprises one nozzle; in other embodiments the second processing enclosure comprises a multitude of nozzles.

The first processing enclosure 101 is equipped with one or more sound generators 1 1 1 and 1 12 with a respective orifice 1 13 and 1 14 through which gas is delivered to the interior of the first processing enclosure 101 . The gas is supplied to the sound generators 1 1 1 and 1 12 via pipes from a steam generator 1 15. The steam generator 1 15 receives water from a tank 1 16 and is configured to deliver a steam at a pressure of 1 .5 to 5 bar to each sound generator 1 1 1 , 1 12. The tank 1 16 and the steam generator 1 15 are commonly referred to by reference numeral 1 17.

Thereby a first processing atmosphere 1 18 is generated within the first processing enclosure 101 . The first processing atmosphere 1 18 represents the temperature, sound pressure, and composition of matter (e.g. steam) that the food products are exposed to when travelling through the first processing enclosure.

One or more of the sound generators 1 1 1 and 1 12 are configured as a static siren e.g. as a Hartmann generator to generate high intensity and high power acoustic waves to at least a portion of said first processing atmosphere causing it to oscillate substantially at the frequency and substantially with the intensity and power of the acoustic waves.

In some embodiments the sound generators 1 1 1 and 1 12 are arranged below the food products when they travel on the conveyor. They may also be arranged to emit sound from the sides of the first enclosure 101 or from above the food products - or arranged in a configuration comprising any combination thereof. There may be installed one sound generator or a multitude of sound generators.

The second processing enclosure 102 is equipped with one or more atomizing nozzles 1 19 and 120 that deliver a spray of an antimicrobial agent towards at least a portion of the food products 105 that travels on the conveyor 103 through the second processing enclosure 102. The spray is illustrated by the cones 121 and 122. The spray may be emitted at a substantially constant rate throughout normal operation of the processing line or it may be gradually adapted to the traffic of food products on the conveyor or other conditions.

The antimicrobial agent is stored in a first tank 123 to provide a local supply of the antimicrobial agent. The supply of antimicrobial agent is mixed with water in a second tank 125 to provide a solution of the antimicrobial agent. The water may be potable ground water delivered at tap ambient temperatures, anywhere from 1 -30°C but most typically in the range of 10-23°C. The tank 125 is pressurized by compressed air from a compressor 124. Via an outlet of the tank 125 the solution of the antimicrobial agent is supplied under pressure to the atomizing nozzles 1 19 and 120.

The mixture proportion of antimicrobial agent to water is chosen to deliver a predefined of concentration of the antimicrobial agent as it is known in the art to the nozzles 1 19 and 120.

In some embodiments the nozzles 1 19 and 120 or at least one of them is configured as an atomizing nozzle. In some aspects, the atomizing nozzle is configured to deliver an air assisted induction charged electrostatic spray (AAIC-ES).

In some embodiments, a flowrate controller is installed to secure that the antimicrobial chemical agent is supplied to each atomizing nozzle at a flowrate in the range of 80-200 millilitres per minute.

The tank 123 storing the supply of the antimicrobial agent is located to avoid excessive heating e.g. by direct sunlight and at a temperature below 30°C (86F). For instance if an antimicrobial agent such as peroxygen, or another oxidizer is exposed to excessive heating there would be a risk of disrupting equilibrium of the agent which in turn would increase reactivity and potentially result in an exothermic reaction which could result in a fire hazard. A peroxygen compound may comprise a peroctanoic acid or a peracetic acid.

The temperature, designated Tp2, of the antimicrobial agent in the second processing enclosure 102 is about the same as the temperature of the water supplied and mixed with the antimicrobial agent as mentioned above.

In some aspects the temperature of the antimicrobial agent in the second processing enclosure 102 is controlled by an automatic controller to obtain a desired surface temperature at the exit way of the second processing enclosure or a desired temperature profile for the surface temperature of the food product during the course of the processing applied in the second processing enclosure. The desired surface temperature at the exit way of the second processing enclosure may be higher, lower or substantially the same as the surface temperature of the food product at a point in time when the food product entered the second processing enclosure - this is illustrated in connection with figs. 4a, 4b and 4c. The automatic controller may e.g. control the temperature by controlling the flow of two sources of water at different temperatures, by a heater or a cooler or a combination thereof. In some aspects the automatic controller controls temperature via a source of gas such as a source of air. In some aspects the gas is fully or partly re-circulated in the second processing enclosure under control of the automatic controller so as to maintain a desired temperature as measured by a temperature sensor in the second processing enclosure and/or to obtain a desired surface temperature of the food products as measured automatically or at intervals by an operator by a contact less temperature sensor such as an IR camera.

In some embodiments residues produced by the processing carried out in the first processing enclosure 101 are drained from the enclosure via drainage 127; and the residues produced by the processing carried out in the second processing enclosure 102 are drained from the enclosure via drainage 126. For instance when the gas supplied in the first processing enclosure is steam, water is drained from drainage 127 and when the antimicrobial agent is an oxidizer such as a peroxygen, water is drained from drainage 126. Peracetic acid decomposes into acetate which eventually decomposes into

carbon dioxide and water in a series of reactions occurring over time. The immediate fluid collected from drainage of the spray would most likely still have at least some acetic acid, acetate, possibly some PAA still decomposing, possibly some hydrogen peroxide still oxidizing etc.

It should be noted that the conveyor 103 may comprise a single conveyor line, a system of like conveyors, or a system of different types of conveyors. In some embodiments the conveyor comprises a station which hands over food products from one conveyor to another. In some embodiments the conveyor comprises a conveyor of a type conveying the food products in a suspended manner. In some embodiments the conveyor comprises a conveyor of a type conveying the food products on a belt, e.g. a belt with a mesh structure or sections e.g. comprising a mesh which is 50% open, e.g. 70-80% open.

In some embodiments the conveyor is configured to one or more of: inclining, turning, flipping upside/down, or rotating a food product to expose different portions of the food product and different portion of the surface thereof to treatment while travelling through one or both of the first and second processing enclosure. Thereby, e.g. the atomizing nozzles 1 19 and 120 may be located to deliver the spray from above and/or from the sides of the food product, while being able to reach lower portions of the food product as well.

In some embodiments the atomizing nozzles 1 19 and 120 are arranged below the food products when they travel on the conveyor.

In some embodiments the conveyor is configured to drop off food products or hand-over food products or branch off the production line such that different processing paths may be provided for production purposes or for quality inspection purposes.

In some embodiments one or both of the first processing enclosure and the second processing enclosure are configured with a longitudinal and upwardly facing slot in a top portion, such as a top plate or roof, of the one or more processing enclosures. Thereby, the conveyor 103, e.g. a rail thereof, can extend above one or both of the processing enclosures and be arranged such that suspension devices (such as a shackle and/or hook), extending from the conveyor and carrying the food products run in the longitudinal and upwardly facing slot, while the food products are conveyed below the top portion of the processing enclosures and inside the processing enclosures. The slot is configured to allow the suspension devices to run therein with a sufficient clearance, but with a narrow slot such that the processing atmosphere inside the one or more processing enclosures is substantially confined by the processing enclosure. The slot may be closed by a gasket that is normally closed, but opens, e.g. due to flexibility, at locations at which a suspension device passes.

Fig. 2 shows a first production line for processing carcasses. The first production line generally designated by reference numeral 200 can be configured for processing one or more particular types of food product among different types of food products.

The production line 200 comprises the portion of a production line 100 described in greater detail in connection with fig. 1 , a pre-processing facility 201 , which may comprise a single pre-processing station or a pre-processing production line, and a post-processing facility 202 which may comprise a single post-processing station or a post-processing production line.

In some embodiments the pre-processing facility 201 comprises a station for lowering the core temperature of the food product. The core temperature of a food product may be lowered by circulating cold air or another type of gas, e.g. comprising CO2, around the food products for a sufficient amount of time. In some aspects the food products are subjected to a cold or super-cold atmosphere in a so-called freeze tunnel. The food product may thereby reach a chilled of frozen state. The core temperature of a food product may alternatively be lowered by submerging the food product into a bath

containing a liquid with a sufficiently cold temperature to reach a desired core temperature of the food product within an acceptable retention time in the bath.

In some embodiments the post-processing facility 202 comprises a station for lowering the core temperature of the food product. The lowering of the core temperature may be performed as described above.

It should be noted that the pre-processing facility 201 and the postprocessing facility 202 refer to any section of the production line upstream of the first processing enclosure and downstream of the second processing enclosure, respectively.

The pre-processing facility 201 , the portion of a production line 100, and the post-processing facility 202 are configured or adapted to the processing of the one or more particular types of food product such that a desired or acceptable food quality is achieved.

In some embodiments the processing atmosphere in the first processing enclosure 101 gives the food products a transient exposure to heat, that is sufficient to raise the surface temperature of at least a portion of the food products at least 4 degrees Celsius or 10 degrees Celsius, while limiting a raise in a core temperature of the food products to a significantly lower temperature than the surface temperature after exposure to the first processing atmosphere.

In some embodiments the food products are exposed to the first processing atmosphere in the first processing enclosure 201 for a first processing duration, which is shorter than that required for blanching of the food products at the temperature in the first processing enclosure.

Thus, since one or both of heat capacity and specific heat capacity may vary significantly among different types of food products and sizes of cut-out portions, and since food products may have complex shapes, it is a complex

task to quantify the first processing duration, the temperature of the first processing atmosphere, and the entropy of the first processing atmosphere. In this respect the following will enable a person skilled in the art to configure a production line as described above.

Processing of different types of food products is described below in accordance with different embodiments. It should be noted that unless parameters and processing steps are indicating otherwise, the parameters and processing steps of one embodiment may be applied in another embodiment.

In general the embodiments comprise a processing step of applying an antimicrobial agent such as an oxygen such as peroxygen solution, e.g. peracetic acid (PAA) or peroctanoic acid. However, this step may be interchanged by a step of rapid chilling or rapid cooling or a step of modified atmosphere processing such as modified atmosphere packaging as described further below.

First embodiment (processing of poultry, whole birds)

Examples of food products processed in accordance with the first embodiment may comprise whole birds of chicken, turkey, ostrich, game hen, squab, guinea fowl, pheasant, duck, goose, emu, or a combination thereof.

At the pre-processing facility, livestock of birds are received, stunned and then slaughtered to deliver eviscerated bird carcasses. The eviscerated bird carcasses have a temperature of about 32-45°C. After evisceration the bird carcasses are washed in an inside-outside bird washer which uses a large amount of water and thereby typically lowers the temperature to below about 32°C e.g. about 28°C. The temperature depends among other things on the temperature of the water used in the washer which may change with the time of year.

At a temperature in the range of about 25-34 °C the eviscerated and washed bird carcasses are conveyed to the first processing enclosure 101 , wherein the surface temperature of the carcasses or at least a portion thereof is raised to a temperature which is more than about 4°C higher than the surface temperature of the carcasses or at least a portion at the time when they entered the first processing enclosure 101 . A raise in surface temperature during treatment in the first processing enclosure may be more than about 10°C, 15°C, 20°C, 30°C, or 40°C. A surface temperature of at least a portion of the food product at the point in time when it leaves the first processing enclosure may be up to or even above 50°C, 60°C, or 80°C.

The temperature in the first processing enclosure is e.g. in the range of 80-95 °C. The duration of the first processing is e.g. in the range of 1 -4 seconds.

The eviscerated bird carcasses are immediately thereafter conveyed to the second processing enclosure 102, wherein the antimicrobial agent is applied. When the antimicrobial agent is a peroxygen solution, e.g. peracetic acid (PAA) or peroctanoic acid, the concentration thereof is selected to be in the range of 1 -2000 ppm. Alternative, food grade antimicrobial agents may be e.g. Nisin, Trisodium Phosphate, or cetylpyridinium chloride.

The eviscerated bird carcasses are thereafter conveyed to the post-processing facility 202 which may comprise a cooling station wherein a step of cooling of the sanitized carcasses is performed. Cooling may be performed by lowering the carcasses while travelling on the conveyor into a tank containing chilled water with a temperature of 1 -4 °C for up to about 90 minutes, e.g. 50-60 minutes. Subsequently, and as a step of the post-processing, the sanitized and cooled carcass may be packaged e.g. by steps comprising wrap packaging.

In some embodiments, in an alternative to lowering the food product into a tank, cooling is performed using an air chiller and exposing the food product to air chilling for about 80-100 minutes, e.g. for about 90 minutes.

Second embodiment (poultry, cut-up parts)

Poultry carcasses may be processed as described in connection with the first embodiment above, with the change that the carcasses proceed to a cut-up station after cooling, optionally via storage at a temperature of 0-4 °C for e.g. about 24 hours.

For processing of cut-up parts of poultry, pre-processing steps may involve air-chilling wherein the cut-up parts of poultry are exposed to a chilled circulating air, e.g. at a temperature of 0.5 to 4 °C.

CLAIMS
1 . A method for sanitizing food products on a production line (200), comprising:
- conveying food products (105) through a first processing enclosure (201 ) and onwards through a second processing enclosure (202);
- generating a first processing atmosphere within the first processing enclosure (201 ) by supplying a flow of gas, with a gas temperature above 70 degrees Celsius, to the first processing enclosure (201 ), wherein at least a portion of the surface of a food product is exposed, while travelling through the first processing enclosure, to a first processing temperature (T1 ) which is above about 60 degrees Celsius;

- inside the second processing enclosure (102), delivering an antimicrobial treatment to the food products (103) when they travel through the second processing enclosure (202).

2. A method according to claim 1 , wherein delivering an antimicrobial treatment to the food products (105) when they travel through the second processing enclosure (202) comprises delivering a spray of an antimicrobial agent (123) towards the food products (105) that travels through the second processing enclosure (202).

3. A method according to any of the preceding claims, wherein the antimicrobial agent is an oxygen-based disinfectant, such as a peroxygen solution.

4. A method according to any of the preceding claims, wherein the antimicrobial agent comprises an antimicrobial agent of the biological type, such as salmonella bacteriophages.

5. A method according to any of the preceding claims, wherein the antimicrobial agent comprises one or more of: peroxygen compound, sodium hypochlorite, chlorine dioxide, hypochlorous acid, hydrogen peroxide, acetic acid, lactic acid, ozone gas in solution, acidified sodium chlorite, potassium hydroxide, sodium hydroxide, citric acid, and a cationic quaternary ammonium compound, such as cetylpridinium chloride.

6. A method according to any of the preceding claims, wherein the surface temperature of the food product is elevated or lowered, while the food product travels through the second processing enclosure, at a rate having a time constant that is relatively short compared to the retention time of the food product in the second processing enclosure.

7. A method according to any of the preceding claims, wherein delivering an antimicrobial treatment to the food products (105) when they travel through the second processing enclosure (202) comprises a step of performing rapid surface chilling of the food product.

8. A method according to claim 7, wherein rapid surface chilling is performed by discharging a gas, with a gas temperature below 0 °C, inside the second processing enclosure (701 ) at a sufficient flow rate to cool the surface temperature of at least a portion of the food product to a temperature below about 0 °C within less than about one minute.

9. A method according to any of the preceding claims, wherein delivering an antimicrobial treatment to the food products (105) when they travel through the second processing enclosure (901 ) comprises a step of applying a modified atmosphere wherein the volume-percentage of one or both of Nitrogen and Oxygen deviates from 78.08% and 20.95% by more than 1 percentage points.

10. A method according to any of the preceding claims, wherein delivering an antimicrobial treatment to the food products (103) when they travel through the second processing enclosure (202) comprises a step of applying a modified atmosphere packaging, MAP.

1 1 . A method according to any of the preceding claims, wherein the food products are exposed to the processing atmosphere in the first processing enclosure (201 ) for a first processing duration; and wherein the first processing duration is in the range of 0.15 to 15 seconds, 0.15 to 10 seconds, or in the range of 0.2 to 5 seconds, or less than about 4 seconds.

12. A method according to any of the preceding claims, wherein the first processing temperature (T1 ) in the first processing enclosure (201 ) is in the range of 80 to 95 degrees Celsius.

13. A method according to any of the preceding claims, wherein the first processing temperature (T1 ) is selected from the group of:

- above 72 degrees Celsius;

- above about 80 degrees Celsius; or

- above about 90 degrees Celsius.

14. A method according to any of the preceding claims, wherein the surface temperature of a portion of the food product is raised, by the first processing atmosphere, to transiently reach a temperature at or above 72°C before exiting the first processing enclosure.

15. A method according to any of the preceding claims, wherein while travelling through at least a section of the first processing enclosure (101 ), a surface temperature of the food product is raised, by an increased surface temperature, (ATsf) to transiently reach a temperature at or above 72°C, while a core temperature of the food product raises less than 30%, such as less than 20% or less than 10%, of the increased surface temperature.

16. A method according to any of the preceding claims, wherein a surface temperature of a food product is elevated from a first surface temperature measured at a point in time when the food product enters the first processing enclosure (101 ) to a second surface temperature measured at a point in time when the food product leaves the first processing enclosure (101 ); and wherein the food product is conveyed to enter the second processing enclosure (102) before the surface temperature falls below the first surface temperature.

17. A method according to any of the preceding claims, wherein the food products are exposed to the first processing atmosphere in the first

processing enclosure (201 ) for a first processing duration, which is

sufficiently long to raise the surface temperature of the food product by more than 4 degrees Celsius or more than 10 degrees Celsius.

18. A method according to any of the preceding claims, wherein the food products are exposed to the first processing atmosphere in the first processing enclosure (201 ) for a first processing duration, which is shorter than that required for blanching of the food products at the temperature in the first processing enclosure (201 ).

19. A method according to any of the above claims, wherein the flow of gas comprises steam supplied to the first processing enclosure (201 ) at a temperature in the range of about 100 to 140 degrees Celsius or in the range of about 120 to 180 degrees Celsius.

20. A method according to any of the preceding claims, comprising the step of:

- applying airborne high intensity and high power acoustic waves to at least a portion of said first processing atmosphere causing it to oscillate substantially at the frequency and substantially with the intensity and power of the acoustic waves.

21 . A method according to any of the preceding claims, wherein said high intensity and high power acoustic waves are ultrasonic acoustic waves.

22. A method according to claim 20 or 21 , wherein said high intensity and high power acoustic waves are generated by a high intensity and high power acoustic wave generator and has an acoustic sound pressure level at approximately 10 cm from an orifice of said generator (1 1 1 ;1 12) selected from the group of:

- at least 120 dB,

- at least 130 dB,

- at least 135 dB,

- at least 140 dB,

- at least 150 dB,

- approximately 130 to approximately 165 dB, and

- approximately 130 to approximately 180 dB.

23. A method according to any of the preceding claims, wherein high intensity sound or ultrasound is generated by a sound generator of the

Hartmann type generator and wherein the pressurized gas is supplied to the sound generator at a pressure in the range of 1 .5 - 5 atm.

24. A method according to any of the preceding claims, the food products being sanitized are selected from one of the following groups: poultry, meat, warm seafood, cold seafood, warm seafood, vegetables, fruit, lettuce, berries, nuts, cereal, and cheese.

25. A production line (100) for processing food products (103), comprising:

a first processing enclosure (101 ) and a second processing enclosure (102);

a conveyor system (103) configured to move a food product through the first processing enclosure (101 ) and onwards through the second processing enclosure (102);

wherein the first processing enclosure (101 ) is coupled to a gas supply system (1 17) delivering a flow of gas at a gas temperature above 70 degrees Celsius via an orifice (109; 1 10) to generate a first processing atmosphere within the first processing enclosure (101 ) exposing at least a portion of the surface of the food products, while travelling through the first processing enclosure, to a first processing temperature (Ts) which is above 60 degrees Celsius;

wherein the second processing enclosure (102) is configured to deliver an antimicrobial treatment to the food products (103) when they travel through the second processing enclosure (202).

26. A production line according to claim 25, wherein the second processing enclosure (102) is configured with an atomizing nozzle (106; 107) to deliver a spray of a supply of an antimicrobial chemical agent (123) towards the food products (103) travelling through the second processing enclosure.

27. A production line according to claim 26, wherein the antimicrobial agent is an oxygen-based disinfectant, such as a peroxygen solution.

28. A production line according to any of claims 25-27, wherein the second processing enclosure (102) is configured to perform rapid surface chilling of the food product.

29. A production line according to claim 28, wherein rapid surface chilling is performed by discharging a gas, with a gas temperature below 0 °C, inside the second processing enclosure (701 ) at a sufficient flow rate to cool the surface temperature of at least a portion of the food product to a temperature below about 0 °C within less than about one minute.

30. A production line according to any of claims 25-29, wherein the second processing enclosure (102) is configured to apply a modified atmosphere wherein the volume-percentage of one or both of Nitrogen and Oxygen deviates from 78.08% and 20.95% by more than 1 percentage points.

31 . A production line according to any of claims 25-30, wherein the second processing enclosure (102) is configured to apply a modified atmosphere packaging, MAP.

32. A production line according to any of claims 25-31 , configured to expose the food products to the processing atmosphere in the first processing enclosure (201 ) for a first processing duration; and wherein the first processing duration is in the range of 0.15 to 10 seconds, or in the range of 0.2 to 5 seconds, or less than about 4 seconds.

33. A production line according to any of claims 25-32, wherein the first processing temperature (T1 ) in the first processing enclosure (201 ) is in the range of 80 to 95 degrees Celsius.

34. A production line according to any of claims 25-33, wherein the flow of gas comprises steam supplied to the first processing enclosure (201 ) at a temperature in the range of about 100 to 140 degrees Celsius or in the range of about 120 to 180 degrees Celsius.

35. A production line according to any of claims 25-34, wherein the first processing enclosure (201 ) is configured to apply airborne high intensity and high power acoustic waves to at least a portion of said first processing atmosphere causing it to oscillate substantially at the frequency and substantially with the intensity and power of the acoustic waves.

36. A production line according to claim 35, wherein said high intensity and high power acoustic waves are ultrasonic acoustic waves.

37. A production line according to claim 35 or 36, wherein said high intensity and high power acoustic waves are generated by a high intensity and high power acoustic wave generator and has an acoustic sound pressure level at approximately 10 cm from an orifice of said generator (1 1 1 ;1 12) selected from the group of:

- at least 120 dB,

- at least 140 dB,

- at least 150 dB,

- approximately 130 to approximately 165 dB, and

- approximately 130 to approximately 180 dB.

38. A production line according to any one of claims 35-37, wherein high intensity sound or ultrasound is generated by a sound generator of the Hartmann type generator and wherein the pressurized gas is supplied to the sound generator at a pressure in the range of 1 .5 - 5 atm.

39. A production line according to any of any of claims 25 to 38, comprising a first storage tank (123) for storing the antimicrobial agent, a second storage tank (125) containing an antimicrobial agent solution, and a compressor (124) for pressurizing the second storage tank (125) and driving the antimicrobial agent solution towards one or more of the nozzles (1 19; 120).

40. A production line according to any of claims 25 to 39, wherein the atomizing nozzle is configured to deliver an air assisted induction charged electrostatic spray (AAIC-ES).

41 . A production line according to claim any of claims 25 to 40, comprising a steam generator (1 15) delivering pressurized steam to the sound generator.

42. A production line according to any of the claims 25 to 41 , comprising a wall (503; 504) separating a first processing volume enclosed by the first processing enclosure (501 ) and a second processing volume enclosed by the second processing enclosure (502); wherein the wall (503; 504) has an opening forming a passage (505) through which the conveyor (103) and a food product conveyed thereon can pass.

43. Use of a production line according to any of the claims 25 to 42 for processing food products.