FIELD OF INVENTION

The present invention is related to the field of food technology. This invention is a process for preparing ready to eat corn with extended shelf life packaged in specialized retort pouches. The pouches have been exclusively designed and standardized to withstand the retort process and to have an extended shelf life of 12months. The product can be stored in ambient climate of 32°C well suited for Indian weather conditions. This process is economically viable as refrigeration is not required for transporting and storing the product.

BACKGROUND OF THE INVENTION

Sweet corn is a variety of maize which is also the most desirable variety of corns owing to its high sugar content. The fruit of the sweet corn plant is called kernel and the collection of kernel in the cob is called the ear. The ear is covered by silk and husk, which has to be removed before processing or cooking.

Corns in general have numerous health benefits, the most important -of all is its antioxidant property. Antioxidants have always been associated with decreasing the chances of getting heart disease and cancer. Processed food usually have lower nutritional value than the fresh produce but in case of corns it retains its antioxidant properties after cooking and the process of cooking also releases ferulic acid which has anticancer properties. Hence processed corns are an ideal choice of snacks for many irrespective of age.

In this fast paced world, many of us prefer fast food or food that can be taken home stored for longer period, reheated and consumed. Such foods are added with preservatives which prevent spoilage from microbes. These preservatives have the advantage of increasing the shelf life of the product thus reducing the production cost. Food preservation is done by various methods like addition of antioxidants, colors, sweeteners, emulsifiers, Stabilizers, thickeners, flavours, irradiation, chemical preservatives or in combination of one or more methods which may alter the taste and texture of the food and also capable of inducing side effects ranging from mild to severe food poisoning, allergy, asthma, liver enlargement, diabetics, heart disease and cancer.

Presently a variety of ready to eat processed corns are available in the market. These products have chemical additives, preservatives and other flavour enhancers which render them unhealthy. Some products require refrigeration or maintenance under frozen state. The nutritive value of such products deteriorate rapidly. Further the fructose content of corns may also drop due to reverse osmosis further altering its taste. Hence a food that contains no preservatives is preferred and would be ideal for all.

The present invention overcomes all these defects as no chemical additives, preservatives or flavouring agents are added at any stage of processing. It is an affordable and healthy food that can be taken by all age groups which doesn't require refrigeration.

SUMMARY OF THE INVENTION

A process for preparing edible corn in retort pouches with extended shelf life without loosing its original taste and texture. The process begins right from seed selection, sowing, manuring, harvesting, travel, pre-processing, quality inspection involving microbial inspection and other parameters, packaging , retorting in customized pouches and shipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 and Figure 2 shows the single and double Cob pouch design respectively. The Single cob pouch as shown in Figure 1 has dimensions of 275 + 25 mm length, 115mm±10mm external width and 95mm ±10mm internal width. As the name suggests it can hold a single cob with trimmed tip of about 80mm Diameter and 160-200 mm length. The double cob pouch as shown in Figure 2 has dimensions of 275 + 25 mm length, 185mm±10mm external width and 165mm ±10mm internal width and it can hold two cobs with trimmed tip of about 80mm Diameter and 160-200 mm length. Both pouches have four sides and are rectangular in shape. They are sealed on three sides and one side is left open for filling in the contents as shown in 1 of figures 1 and 2. Two V nouches are provided on either side at 30 - 40mm down form the sides of the open end. This provision is provided in order to open the pouch.

DETAILED DESCRIPTION OF THE INVENTION

The processing of edible sweet corns starts from the process of seed selection. A superior quality seed like Sugar 75 (Syngenta), SW2/3(CP) were found suitable for this purpose particularly for cultivation under the South Indian weather conditions. The corn plants were farmed scientifically. A specific composition of manure i.e., an organic vermicompost of 1 ton per hectare was found to improve the yield by 2 - 3%. A further increase of about 8 -12% in yield was achieved by use of germination mats. The corns were at its best when harvested after 75days in summer and 80 days in winter. Corns harvested during this period showed a brix level of 13.6 to 16 and were at its best of freshness, taste and quality. The brix level were measured using refractometer. The size of the corn is 6-8cm in Diameter and 16 to 18 cm in length.

Utmost care must be taken during transportation of harvested corns. The corns must be transported within 10 hours of harvesting to reduce loss in sweetness during transit, if there is any delay they need to be transported under temperatures lesser than 5°C. Basically corns are exothermic in nature and when stored in heaps, the core get hot reducing the sugar content of corn. The sugar content is measured in terms of brix. The brix level of corn usually decreases each day, there is a drop of 2-2.5 Brix per day under normal conditions of storage. A drop below 12 Brix renders it unsuitable for processing and consumption. Hence it has to be transported at the earliest possible preferably in open truck under good aeration.

As soon as the freshly harvested corn arrives the processing unit, they are dehusked, with top tips chopped and sorted out based on their weight ranging between 400to 580 grams. The top tip of the corn has to chopped for economic reasons, the top tip has very less kernels hence its inclusion was not necessary and the top tip was trimmed off to accommodate inside the pouch. This process reduces the size of the pouch by 30mm i.e., from 300mm to 270mm.

The corns may have very high loads of microbes depending on the type of water used for irrigation. In order to minimise the microbial load the peeled corn is dipped in a chlorine dip of concentration 100 - 200 ppm followed by blanching with hot water at 70 - 80°C for 15 minutes. The corn is then packed in customized multilayered pouches of single and double pack the dimensions of which are 275 ± 25 mm length, 115mm±10mm external width, 95mm ±10mm internal width and of 275 ± 25 mm length, 185mm±10mm external width, 165mm ±10mm internal width respectively. The pouches are rectangular in shape and sealed on three side with one open side provided to fill in the liquid and solid contents. The retort pouch is also provided with V nouches on either sides of the upper portions so that it is easy to tear. The retort pouches are multilayered laminates specifically designed and customized to suit the processes of retorting under conditions of high pressure and heat. Four different combinations of casting as mentioned in Table 1 were tried and the best results were obtained with pouches having Aluminium oxide coating. The retort pouches are made up of three extruded laminate films, the outer layer is vacuum coated Aluminium oxide or silicon Oxide or Uncoated PET (Polyethylene Terephthalate) laminated with second layer of oriented polyamide (nylon) and 3rd layer / contact layer consisting of polypropylene, an Alternate Structure can be a two layer structure with one layer of polyamide with a cast polypropylene. The three/ two layers of laminates will reduce the Oxygen transmission rate, which is lower than 0.26 cc/day. They also have very high resistance for temperature and also have a very low thermal expansion, they are adverse to stress cracks and doesn't stand any chance for contamination or loss of aroma It also minimises the change in internal pressure of air in the pouch.

These retort pouches are filled with the pre processed corn measuring around 160-200mm along with 0.3-0.4% of salt and 8 - 14% of water. 1.5% to 3% Sugar/fructose may be added to prevent the loss of fructose due to reverse osmosis. The filled retort pouches are sealed in a vacuum sealing machine at an inclination of angle 45 to prevent water from flowing out and the corn stays firm inside the pouch. The vacuum bed of the vacuum machine showed the best packing at 45 Degree than at 0 degree or 90 Degree due to the liquid content inside. If the vacuuming is done at 90 degrees then the cob is inclined to one side of the pouch. The ambient atmospheric pressure is reduced below 75 Torr (10KPa) bar pressure using a multistage vacuum pump.

Table: 1

The filled, vacuumed and sealed retort pouches are loaded inside a steam retort and retorted to reach a FO ranging 18 - 53 minutes between a temperature of 108-126°C under 2 - 4 bar internal pressure. The pack after a holding time is rapidly cooled down to 58-65°C by purging cold water on it, in less than 7 minutes (Rapid Cooling).

Table: 2

TPC - Total Pathogen Count
TBC - Total Bacterial Count
CFU - Colony forming unit

The resultant product is checked for the presence of any microbial contamination. Microbial load is checked in raw corn, post blanching, reverse osmosis water used for processing and in the finished product. Microbial testing were done for Total pathogen Count/Total bacterial count. The raw corn showed very high number of counts whereas the finished product showed no counts. The results are as tabulated in table 2. The resultant product is allowed to cure for 3 -7 days and stored at room temperature. The product remains unaltered at temperature of about 32°C. The resultant product where studied for stability. The product was stable and fit for consumption for more than 12 months without any change in the colour, texture and taste.

We Claim,

1. Processing of sweet corns with extended shelf life under ambient conditions in customized retort pouches.

2. A process as claimed in claim 1, wherein the corn is dehusked and 2 to 3cm top tip of cob containing fewer kernels are trimmed to accommodate the corn in the customized retort pouches which gives considerable cost reduction.

3. A process as claimed in claims 1 & 3, Wherein the dehusked and top tip trimmed corns are dipped in water containing 100-200ppm chlorine and blanched in 70 -80°C temperature to minimise microbial contamination

4. A process as claimed in claims 1 & 4, wherein the corn is packed in the customized retort pouch in single or double pack along with 8 - 14% of water and 0.3-0.4% salt to maintain the right taste .

5. A process as claimed in claim 1, where in the customized retort pouches are made of three layer laminate with AlOx coated PET is laminated to a layer of polyamide to a cast extruded polypropylene, which is highly resistant to stress cracks during the intense thermal activity inside the retort and also while transporting.

6. A process as claimed in claim 1, 5 & 6, where in the dimensions for single and double retort pouches are 275 + 25 mm length, 115mm±10mm external width, 95mm ±10mm internal width and of 275 + 25 mm length, 185mm±10mm external width, 165mm +10mm internal width respectively.

7. A process as claimed in claim 1 & 7, wherein v-nouch (slits) are provided at either side of the retort pouches for opening at about 30- 40mm down form the top.

8. A process as claimed in claims 1 & 5, wherein, 1.5% to 3% Sugar is added to prevent the loss of fructose due to reverse osmosis.

9. A process as claimed in Claims 1, 5 & 9, wherein the filled retort pouch is sealed on a vacuum bed at an angle of 45 in a vacuum sealing machine to prevent the loss of fluids with an internal pressure of below than lOPsi (75 Torr)

10. A process as claimed in claims 1 &10, wherein the filled vacuum sealed retort pouches are retorted to reach a Fo ranging 18 - 53 minutes between a temperature of 108 - 126°C under 2 - 4 bar internal pressure.

11. A process as claimed in claims 1 &11, wherein the retorted product after a holding time is rapidly cooled down to 58-65°C by purging in cold water in less than 7 minutes.

12. A process as claimed in claims 1 & 12, wherein the product is allowed to cure for 3 -7 days.

13. A process as claimed in the above mentioned claims wherein the products have shelf life of 12 months upto temperatures of about 32°C