Introduction to Food Preservation Part II

Basically food preservation styles are of many types some are discussed in earlier session. The previous ones were the conventional process whereas the in this blog there is the food preservation equipment system which are eco-friendly. The preservation system may use the same principle as discussed in earlier ones. In this session we discuss some of the commercial equipment used in food preservation.
a. Equipment for drying purpose and eco-friendly
i. Heated air drying system
Figure CIGR handbook of agriculture engineering
Typically this type of dryer is the low cost dryer this uses the application of the heater air with low relative humidity. When heated air is collected via motor and when the heated air enters to the drying chamber , this subsequently dries the high moisture product. This is the low cost design the product prices ranges from 10000-150000 depending on the raw materials used.
ii. tunnel drier
Source: CIGR handbook of agriculture engineering
This is the mini type of the solar tunnel dryer. This type of dryer is used for drying the medicinal and aromatic plants. This is tunnel dryer, the dryer is could be as long as 4.5m, for better reduction of the moisture within short time.
iii. Solar cabinet dryer
Solar cabinet dryer is another type of solar energy dryer. The figure of the dryer is given in the below:
This type of dryer is mostly used for drying cereals, legumes, pulses as well as the potato chips drying
iv. Microwave heater
Microwave heater is also used in drying the food; it’s expensive but very rapid and runs with the application of the electricity. It’s been used in kitchens but in large drying application it’s hardly used due to high usage of electricity.
v. Osmotic dehydration
Osmotic dehydration is another application of the dehydration which uses the osmosis principle for drying. Water is leached out by use of high concentration solution like salts and sugar. Due to difference of pressure between the food and solution the water is leach
out and subsequently moisture decreases. This method is used in traditional lemon pickle called निम्कि.
vi. Drum dryer
This is another system of the dryer in this drying system the food to be dried is passes through the heated drum and when the drum rolls the moisture of the food is reduced. This drying system is expensive and it had not been practiced in Nepal till now.
Source PJ Fellows
vii. Tunnel dryer
Tunnel drier use the application of the velocities, two like air as well as the product. In this type of drying system the air is passed through one velocity and food is passed
through another velocity. The contact period of the food and air is set to that food reduces to desired moisture content.
Source PJ Fellows
[There are other many methods too but they are quite complicated I hope the above drying equipment were easy to understand]
viii. Continuous pasteurizer
As discussed in the earlier day there are two types of pasteurization LTLT and HTST. LTLT pasteurization could be achieved in small scale industries ever at home. The process involves holding the milk at 65oC for 30 minutes but in the industrial application HTST one is preferred. The time temperature profile for the HTST is 73-75oC for 15 seconds so a continuous method of pasteurization is used.
Perhaps this video may be useful
For generating the steam for pasteurization either electricity could be used or the fuel could be used.
[In the coming day I will mention how quality control and preservation helps in building entrepreneurs]
Thank You
Abhishek Khadka



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