Food preservation methods

1. Write about the importance of food preservation?

• To keep the quality of the food
• By using food preservation method the life time of the food was increased with good quality.

2. Name some high temperature food preservation operations?

• Sterilization
• Pasteurization
• Blanching

3. Describe “blanching” with example?

     Blanching is an essential step of heat processing used for agricultural products. Fruits and vegetables are blanched prior to canning , freezing (or) dehydration . The aims of blanching are

• To inactivate the native enzymes and to destroy enzyme substrates such as peroxides
• To reduce the microbial load in the food raw material.
• To soften and shrink food facilitating the filling in to containers.
• Expel cellular gases thereby reducing corrosion and improve the texture particularly of dehydrated foods.

Example ; A costlier method is microwave balancing applicable for fruits and vegetables packaged in filmbags.

4. With example define baking?

      Baking is another important heat conversion operation in the manufacture of bread, biscuits and cakes. A series of complex chemical reactions occur at different temperature ranges during the baking of fermented food such as bread. It is necessary to control the heating carefully to desired colour , flavor , aroma and texture of the finished bread.

5. What is pasteurization?

     Pasteurization involves a comparatively low order of het treatment, generally at temperature below the boiling point of water . pasteurization treatments depending on the food.

6. Define pasteurization of milk?

     Milk is pasteurized at 62.80 degree C for 30 minutes (or) by high temperature short time (HTST) pasteurization at 72 degree C for 15 seconds. The choice of temperature and the time of pasteurization depends on the type of food.

7. What are cryogenic liquids?

Cryogenic liquids are liquefied gases of extremely low boiling point, such as liquid nitrogen &liquid carbon dioxide with boiling points of -1960 degree C and -790 degree C respectively. Today liquid nitrogen is the most commonly used cryogenic liquid in freezing of foods.

8. Define refrigeration and freezing?

     Refrigeration is the gentlest method of food preservation as it has no adverse effect on taste ,texture and nutritive value. Ideally , refrigeration of perishables should start immediately after harvest (or) slaughter and should be maintained throughout transportation , warehousing and storage to ultimate use.
Example; this is particularly true of certain metabolically active fruits and vegetables.
     Freezing has been a major factor in making available a variety of convenience of foods to the consumer apart from preserve foods for prolonged periods. Proper freezing preserves food without major changes in size, shape , texture , and flavor of variety of foods of plants & animal origins.
Example; cakes, cookies, waffles are frozen and marketed.

9. What are irradiation techniques in food industry?

The radiation treatment is of given to foods is of any one of the following three types

1. Radappertization
2. Radicidation
3.  Radurization

10. What are the advantages of fermentation?

• Fermented foods can be more nutritious than their unfermented counter parts.
• Fermented foods can be improved nutritionally has to do with liberation of nutrients locked into plant structures and cells by indigestible materials
• Fermentation especially by certain molds , breaks down indigestible coatings and cell walls both chemically and physically.
• Fermentation enhance nutritional value especially of plant materials, involves enzymatic splitting of cellulose, hemicellulose & related polymers that are not digestible by humans into simpler sugars and sugar derivatives.

11. Define freezing and frozen storage?

Freezing properly done to preserve food without causing major changes in the size, shape, texture, colour and flavour. Freezing permits much of work in preparing food items or an entire meal to be done prior in freezing shop.
The wide array of available frozen food products many sold in their final serving dishers, represents a major revolution in the food industry and reflect gross changes in eating habits.

12. Give an account of application of drying in food industries?

The purpose of drying of food includes:

• Preservation of food
• Decrease in the weight and bulk of foods to shipping and canning cost.
• Production of convenient item such as instant coffee, instant mashed potatoes.

13. Classify the methods of drying?

Drying can also be done in following ways:

1. Sun drying
2. Drying by mechanical dryers
3. Freeze drying.

14. Give applications of freeze drying?

      Batch freeze dryer is used in freeze drying of coffee, tea, meat, fish and some vegetable and fruit products.

15. Classify the methods of freezing of foods?

There are 3 methods of freezing employed in commercial practice. They are:

• Air freezing
• Indirect contact freezing
• Immersion freezing

16. What is the advantage of microwave heating?

     The use of micro waves can result in very rapid heating but requires special equipment, and often specific packing materials.

17. Define the term irradiation?

     Radiation may be defined as the emission and propagation of energy through space (or) a medium. These radiations have sufficient energy to ionize molecules in their path. They destroy micro organisms in food sufficient without raising the temperature and hence irradiation process is termed as cold sterilization.

18. what are irradiation techniques in food industry?

The radiation treatment is of given to foods is of any one of the following three types

1. Radappertization
2. Radicidation
3. Radurization

19. Write a short note on fermentation?

    Fermentation involves the use of microbial metabolic process in which carbohydrates and other nutrients are oxidized partially to a variety of break down products such as alcohols, acids, amino acids, other metabolites and antibiotics and a small amount of energy.

20. Name few fermented food manufactured vegetables and dairy products?

Vegetables
Cucumbers → dill pickles , sour pickles
Vegetables and milk → tashana
Coffee cherries → coffee beans
Dairy products
Butter → sour cream butter, cultured butter , ghee
Cheese → unripened, cottage, pot, schmierkase, cream

21. What is meant by hermetic closure in packaging?

      This refers to a container that is sealed completely against the ingress of gases and vapors. Such a container as long as it remains constant will also be impervious to bacterial, yeasts, molds and dirt from dust and other sources. The most common hermetic containers are rigid metal cans and glass bottles.