Low cost preservation technologies
Describes low cost preservation technologies for food items.
Low cost technology for preservation of vegetables
Vegetables like cabbage, cauliflower, green papaya, bean, pea, carrot, turnip, radish, pumpkin etc, can be preserved by this technique up to a period of about three months without much alteration in the nutritive value of the produce.
- Wash the vegetables thoroughly in clean water. Remove blemishes, rotten part, if any.
- Shred the vegetables, preferably with a stainless steel knife.
- Weigh 2 kg finely (1/8" to 1/16" thick) shredded cabbage and keep it in a clean plastic sheet or container and mix it with 2 kg shredded vegetables (almost any type of vegetables may be used except potato, sweet potato etc.). The proportion of cabbage may be more but not less than 50%. Cabbage contains desirable lactic acid bacteria and the nutrients which help in fermentation. (When cabbages are not available, radishes or cucumbers may serve the same purpose).
- Add 22.5 gm of salt (NaCl) per Kg of shredded vegetables. Mix thoroughly for 3 to 5 minutes. Put the mixture in plastic/earthen/wooden buckets. (Wax lining is necessary for-earthen and wooden vats). Press vegetable mix with hand so that brine can come up at the top of the vegetables.
- Cover the container with a plastic sheet (200 gauge) which touches the surface of vegetables to avoid contact with air.
- Pour water (which must not mix with the vegetables) at the top of plastic sheet so that adequate pressure on the vegetables is ensured. Fasten the bucket with a thread around the neck so that the entire system becomes almost air-light.
- Keep the bucket in a safe place. Don't open the cover of the bucket. This will spoil the product. Vegetables can be kept in this way for a period of about three months.
- Once it is opened, the materials should be consumed on the same day. If it is not possible special presentation techniques like heat processing (bottling), refrigeration or addition of preservatives may be applied to preserve it for longer period of storage for marketing.
- Vegetables get sour by fermentation. If the product is too sour it may be washed thoroughly in water/hot water to make it free from acid and salt. Boil the vegetables and cook with spices to suit individual taste.
Fermented juice in the vat is also nutritionally sound. This has a characteristic odour and is rich in vitamins B and C. The liquid has mild laxative effect. Heat the juice for a few minutes after adding a little sugar and spices and use as a soft drink. It is also a good appetizer.
Source : Department of Food Technology and Biochemical Engineering, Jadavpur University, Calcutta- 700 032
Low cost egg preservation technology
This simple technology of preserving the eggs by salting is an economical one and materials required are cheap and readily available.
Bricks, hammer, sieve, common salt, pan and water.
Powder the bricks by hand-pounding and sieve them. Powder the common salt in a similar manner and mix the brick powder and common salt in a ratio of 2:1 respectively, by volume. Then add water to this mixture and knead it like a dough.
The second stage comprises of testing whether the egg is fit enough for preservation or is already fertilized. The test is simple as all you have to do is put it in a bowl full of water. If the egg floats it is unfit and if it sinks then it is still good. Now, keep these selected eggs in a pan and cover them with the brick-salt dough.
Keep this pan in shade for ten days, maintaining the wetness of the dough by frequent sprinklings of water. In the meanwhile, salt penetrates into the eggs and preserves them. Wash the eggs after 10 days and store them.
The salted eggs taste good and can be stored to one and a half months.Source : Central Food Technology Research Institute, Mysore, Karnataka
Zero Energy Cool Chamber
Zero energy cool chamber is a low cost alternative to store horticulture produce. This is an on-farm storage chamber, for fresh fruits, vegetables and flowers to extend their marketability. Due to their high moisture content fruits and vegetables have very short life and are liable to spoil.
Moreover, they are living entities and carry out transpiration, respiration and ripening even after harvest. The spoilage of fruits and vegetables can be controlled by reducing the storage temperature. The zero energy cool chamber can be constructed easily with materials like brick, sand, bamboo, khashkhas/straw, gunny bag etc. The chamber can keep the temperature 10-15OC cooler than the outside temperature and maintain about 90% relative humidity. It is most effective during the dry season.
- Select an upland having a nearby source of water supply.
- Make floor with brick 165 cm x 115 cm.
- Erect the double wall to a height of 67.5 cm leaving a cavity of 7.5 cm.
- Drench the chamber with water.
- Soak the fine river bed sand with water.
- Fill the 7.5 cm cavity between the double wall with this wet sand.
- Make a frame of top cover with bamboo (165 cm x 115 cm) frame and sirki, straw or dry grass etc.
- Make attach/ shed over the chamber in order to protect it from direct sun or rain.
- Keep the sand, bricks and top cover of the chamber wet with water.
- Water twice daily in order to achieve desired temperature and relative humidity or fix a drip system with plastic pipes and micro tubes connected to an overhead water source.
- Store the fruits and vegetables in this chamber by keeping in perforated plastic crates.
- Cover these crates with a thin polyethylene sheet.
- The cool chamber should be reinstalled once in 3 years with new bricks utilizing the old bricks for other purposes.
- Try to site in a place where breezes blow.
- Build in an elevated place to avoid water logging.
- Use clean, unbroken bricks with good porosity.
- Sand should be clean and free of organic matters, clay etc.
- Keep the bricks and sand saturated with water.
- Roof over to prevent direct exposure to sun.
- Use plastic crates for storage; avoid bamboo baskets, wooden/fiber board/boxes, gunny bags etc.
- Prevent water drops coming in contact with stored material.
- Keep the chamber clean and disinfect the chamber periodically with permitted insecticide/ fungicide/ chemical, to protect from fungus, insect/ pests, reptiles etc.
Areas of Application
- Short term storage of fresh vegetables, fruits and flowers.
- Growing of white button mushroom.
- Ripening of tomato and banana.
- Plant propagation.
- Storage of processed fruit products.
- Helps avoid distress sale of fresh fruits, vegetables and flowers.
- Ensures better marketability of fresh horticultural produce than ambient.
- Retain nutritive value.
- Environment friendly storage system with no pollution.
100 q/chamber with the scope of scaling up to the tune of 6-7 tonne/chamber
- Building: Open shed (ventilated)
- Land: 100 m.sq.
- Water: 25-50 ltr./day (depending on location)
- Manpower: Total 2 including 1 technician, 1 unskilled