FIELD OF THE INVENTION AND USE OF INVENTION
This invention relates to non-thermal treatment of liquid foodstuff at ambient temperature using electrochemical cell equipped with boron doped diamond electrode. The present invention can be used for reducing micro-organism count in liquid milk and many other liquid foodstuffs.
PRIOR ART AND PROBLEM TO BE SOLVED
Treatment of liquid foodstuff is required to kill or reduce the count of microorganisms in the liquid foodstuff so that the shelf life of the liquid foodstuff can be increased to make it fit for human consumption. Pasteurization is the general term used for the process used for treatment of liquid foodstuff. It is the process of heating liquids or foods to kill micro-organisms (such as Brucella, Campylobacter, E. coli 0157;H7, Listeria, Mycobacterium bovis, Salmonella, and Yersinia) that can cause disease. It was developed by Louis Pasteur in 1864, and the practice became commercialized around the late 1800s and early 1900s. In addition to improving consumer safety, pasteurization can improve the quality and shelf life of foodstuffs.
Conventional method for Pasteurization includes:
1. High Temperature Short Time Treatment: Milk is pasteurized at 161 F for 15
seconds.
2. Low Temperature Long Time Treatment: Milk is pasteurized at 145 F for 30
minutes. 3. Flash Pasteurization: This type of pasteurization, which involves high temperature for 3 to 15 seconds followed by cooling and packaging, is used for drink boxes and other liquids that can be stored for long periods of time without refrigeration. 4. Steam Pasteurization: Pressurized steam is used to kill E. coli, Salmonella, and Listeria in beef carcasses. Exposure of the beef to steam results in a surface temperature of about 200 F.

5. Irradiation Pasteurization: Exposure to gamma rays can prevent the growth of some foodborne microbes in foods such as meats, spices, and produce.
6. Ultrapasteurization: Heating milk or cream to 280 F for 2 seconds can extend the refrigerated shelf life of milk from 60 to 90 days.
7. Ultra-High Temperature Pasteurization: Heating milk to 280 to 302 F for 1 or 2 seconds followed by packaging in airtight containers allows storage without refrigeration for up to 90 days.
All the above methods of treatment of liquid foodstuff are thermal in nature, i.e. they depend on increase in temperature for short period of time to destabilize the microorganisms from the liquid. This temperature dependence of the process makes the conventional methods expensive. Such methods also call for certain centralization of the treatment process leading to increase in treatment cost. The processes are also resource intensive on energy and water fronts.
The present invention provides a non-thermal alternative to pasteurization of liquid foodstuff. Unlike thermal methods, the present invention treats the liquid foodstuff at ambient temperature. The count of the micro-organisms in the liquid foodstuff is reduced through interaction with oxidants/free hydroxyl radicals generated in-situ in the liquid foodstuff using an electrochemical cell equipped with boron doped diamond electrode.
The method of pasteurization is well described in several books on processing of liquid food stuff and also in several patents on the same. Thermal processing of liquid foodstuff requires several specialized equipments to control the process with each supplier having its unique design and process logic.
WO 2008/066470 discloses a non-thermal method for treatment of liquid foodstuff using ozone gas, which is created using commercial ozone generator. The gas so generated is injected in the liquid foodstuffs like milk, juices, etc. The said disclosed invention does not employ only ozone as the agent for destruction of

micro-organisms. There are few disadvantages of the said prior art: ozone has to be generated on-site and using complex and expensive equipments, it has to be injected into the liquid foodstuff to be treated. Apart from the high cost of the equipment and the complexity of the equipment, to handle ozone itself is hazardous.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide a simple method to reduce the count of micro-organisms in liquid foodstuff without using complex or costly equipment and without raising the temperature of the liquid foodstuff. Another object of the present invention is to provide a method by which the shelf life of liquid foodstuff significantly improves. Yet another objective of the present invention is to provide a low cost solution to the problem of reducing the count of micro-organisms in liquid foodstuff.
SUMMARY OF THE INVENTION
It is known and proved thorough various laboratory and field level studies that boron doped diamond electrode has a unique capability of generating hydroxyl radicals, which capability is incomparable with electrodes of other materials. Though some electrodes of other materials may exhibit some capability of generating hydroxyl radicals, such other electrodes are not stable at high current densities and the efficiency of generating hydroxyl radicals is poor compared to that of a boron doped diamond electrode. The hydroxyl radicals generated on the surface of a boron doped diamond electrode leads to formation of secondary oxidants like ozone, hydrogen peroxide and other per oxygen compounds from water and dissolved gases within the liquid. Thus, the combination of primary hydroxyl radicals and secondary oxidation leads to effective reduction of micro-organisms in the liquid foodstuff. The microorganisms are unable to acclimatize to the mixed oxidant environment. As the very aim of pasteurization is not to kill all the micro-organisms, but to achieve log 2 to log 3 reduction, the mixed oxidants generated in-siiu using boron doped diamond

electrode, are capable of meeting the statutory requirement for bacterial count for milk and other liquid foodstuff.
The present invention discloses a method for reducing the count of micro-organisms in liquid foodstuff. The method does not require raising th'e temperature of the liquid foodstuff. The equipments required are not complex. The liquid foodstuff is stored in a container or a tank. An electrochemical cell having at least one anode which is a boron doped diamond electrode. The boron doped diamond electrode can be a boron doped diamond coated film on suitable substrate or it can be a free standing crystalline boron doped diamond or any other variation thereof. A circulating pump circulates the liquid foodstuff through the said electrochemical cell. Direct current is supplied to the said electrochemical cell. A programmable logic controller is used to control the circulation rate and also the current to be supplied to the said electrochemical cell and also the duration of circulation as well as the length of time for supplying the current. The said programmable logic controller can be programmed with such parameters as found to be optimal for the type and quantity of the liquid foodstuff to be treated. The treatment is simple in application and unlike conventional process poses no danger to the natural flavor, texture or composition of the liquid foodstuff. The proposed invention does not limit itself to stationery processing. The processing of liquid can be done on the go, as the milk travels from collection centers to processing center.
Liquid foodstuff has natural electrolytes present in them, thus, they respond readily to direct current leading to formation of oxidants within the electrochemical cell. The process employs low voltage, low amperage direct current which is very safe compared to that required for corona discharge based ozone generation. The method as described above generates hydroxyl radicals in-situ. The hydroxyl radicals have a tendency to kill the micro-organisms present in the liquid foodstuff being treated. By experimentation, depending on the type and quantity of liquid foodstuff to be treated and the minimum count of micro-organisms to be not killed according to statutory requirements, the parameters for the treatment of the liquid foodstuff can be arrived

at and the said programmable logic controller can be accordingly programmed. The method is simple and can be scaled depending on the type and quantity of the liquid foodstuff to be treated.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 shows the schematic of the system used for treatment of liquid foodstuff in accordance with the present invention.
DETAILED DESCRIPTION OF THE DRAWING
Fig. 1 shows container 10 in which the liquid foodstuff to be treated can be stored. The material for the container 10 depends on the type of the liquid foodstuff to be treated. The material for the pipe 60 through which the liquid foodstuff to be treated also depends on the type of liquid foodstuff. The pipe 60 connects the container 10 with electrochemical cell 20 and circulating pump 30. Electrochemical 20 has at least anode which is a boron doped diamond electrode. Electrochemical cell 20 is connected to direct current power supply 40. There is also provided a programmable logic controller 50 which controls the speed of circulating pump 30 and the ampeaage of DC power supply 40. Programmable logic controller 50 is programmed with the appropriate treatment parameters for the type and quantity of liquid foodstuff to be treated. Accordingly, programmable logic controller 50 controls the circulation rate of the liquid foodstuff by controlling circulating pump 30 and also controls the length of time for which direct current is supplied using direct current power source 40 to electrochemical cell 20 to energize electrochemical cell 20.
BEST METHOD OF PERFORMING THE INVENTION
Depending on the type and quantity of the liquid foodstuff to be treated, the size and material of container 10 is selected. Container 10 is filled with the liquid foodstuff to be treated. Once container 10 is filled with the liquid foodstuff, the liquid foodstuff

is circulated using circulating pump 30 through pipe 60 to electrochemical cell 20. The programmable logic controller ensures that the circulation rate inside the electrochemical cell is within the prescribed limits of operation. Programmable logic controller 50 monitors the circulation rate of the liquid foodstuff and permits circulation until the pre-determined and programmed parameter is achieved. At this stage, direct current power source 40 is turned on by programmable logic controller 50 to energize electrochemical cell 20. As soon as the direct current power supply 40 is turned on, hydroxyl radicals start getting formed at the boron doped diamond electrode surface which starts destroying the micro-organisms present in the liquid foodstuff.
The exact value of circulation rate, current and voltage is based on the pilot trials conducted at the facility. It also depends on the bulk of liquid food stuff which is being treated, its physical characteristics and source of origin. The total time of circulation / treatment depends on the characteristics of the liquid foodstuff. Once the initial volume of liquid foodstuff is circulated through the electrochemical cell 20 for a predetermined time it is taken to another vessel and a new batch is taken.
The abovementioned mode of operation is a batch mode for treatment of liquid foodstuff. As a person skilled in the art will readily understand, the disclosed method can be employed in a continuous manner without departing from the scope and spirit of the present invention.
The possibility of realizing the disclosed invention is not limited to the above methods, it can be realized using any other arrangement either in a stationary vessel or in a mobile container. As the process does not require any external heat source, the process can be conducted even on mobile container mounted on a truck, for example, using the truck battery to provide the current to energize electrochemical cell 20.

The disclosed invention also does not limit the scale to which the proposed invention can be applied. The simplicity of the process makes it applicable to few hundred litres to few lakh litres of liquid foodstuff daily.
EXAMPLE OF THE PROPOSED INVENTIION
• Liquid foodstuff to be treated: Unpasteurized milk
• Total volume of milk: 10 litres
Container size: 12-13 litres and material: polypropylene
• Magnetic circulating pump used for circulation of liquid foodstuff
Total circulation time: 45 minutes
Current density: 20 mA/sq. cm.
Electrochemcial cell with boron doped diamond anode and cathode
To compare the results with the pasteurized milk standards in India, Specific Plate Count (SPC) was undertaken as per 18:5402-2002. The results of the test are as follows:

Unpasteurized Milk After 15 minutes of treatment After 30 minutes of treatment
5,73,333 3,60,000 5,200


For India, pasteurized milk needs total SPC count to be around 50,000 CFU/ml. The results clearly show that the disclosed method of invention is capable of bringing down the SPC well below the statutory requirement.
Though the example is of milk, the proposed invention can be well applied to any other liquid foodstuff like fruit juice, beverages and even water.

We Claim,
1. A method for reducing the count of micro-organisms in liquid foodstuff at ambient
temperature, the method comprising
a. storing the liquid foodstuff in a container;
b. using a circulating pump, circulating the liquid foodstuff through an
electrochemical cell having at least one boron doped diamond electrode;
c. supplying direct current to the said electrochemical cell;
d. generating hydroxyl radicals in situ;
e. controlling using a programmable logic controller the circulation rate, the
current to the electrochemical cell and duration thereof;
f. reducing bacterial count in the liquid foodstuff through the hydroxyl radicals.
2. The method of claim 1 wherein at least one anode of the said electrochemical cell is
boron doped diamond electrode.