3.1 BIOCHEMISTRY OF FOOD SPOILAGE

(3.1.1 Factors causing food spoilage during food ripening, vegetable maturation and their

control)PRESENTED BY

JYOTI DEVENDRA ADALA

He may live without books- what is knowledge but grieving.

He may live without hope- what is hope but deceiving.

He may live without love- what is passion but pining.

But show me the man who can live without EATING!

FOOD SPOILAGE

Food spoilage is the process in which food deteriorates to the point in which it is not edible to humans or its quality of edibility becomes reduced.As a result abnormal colors, off flavors or other alterations develops.

CAUSES

1) PHYSICAL SPOILAGE2) BIOLOGICAL SPOILAGE -Micro biological -Macro biological3) BIOCHEMICAL SPOILAGE - Enzymatic reactions - Non enzymatic reaction4) CHEMICAL SPOILAGE

PHYSICAL SPOILAGE

Caused by the inappropriate transport, handling and storage.

Food spoilage can be caused by physical factors, such as temperature, moisture and pressure acting upon the foods.

ACTION OF MICROORGANISMS

Bacteria and fungi are the principal types of microorganisms that cause food spoilage when the conditions for their growth are appropriate.

The typical microorganisms that cause food spoilage are bacteria (e.g., Lactobacillus), yeasts (e.g., Saccharomyces).

ACTION OF MACROORGANISMS

Food are mechanically damaged by insects, rodents, worms, etc.

For example: The hole on the surface of tomatoes, cucumber, brinjal indicate that they are harboring larvae of insects.

ENZYMATIC SPOILAGE

Enzymes are large protein molecules that act as biological catalysts, accelerating chemical reactions without being consumed.

After the harvesting of fruits, enzymes remain active within the cells. They continue to catalyse the biochemical processes of ripening and may eventually lead to rotting.E.g.: banana.

NON ENZYMATIC SPOILAGE

The Maillard Reaction (also known as browning) is a type of non-enzymatic browning which involves the reaction of simple sugars (carbonyl groups) and amino acids (free amino groups).Non enzymatic browning causes spoilage during the storage of dry milk, dry whole eggs and breakfast cereals.

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FOOD PRESERVATION METHODS

1) FREEZING AND CHILLING

2) THERMAL PROCESSING

3) FOOD IRRADIATION

4) DEHYDRATION

5) NATURAL AND CHEMICAL PRESERVATIVES

FREEZING AND CHILLING

CHILLINGThe life of many foods may be increased by storage at temperatures below 4° C.FreezingThe freezing of food involves lowering its temperature below 0° C resulting in the gradual conversion of water present in the food into ice.

THERMAL PROCESSING

Heat is effective in destroying vegetative cells. However excessive bring about undesirable changes.1) Canning2) Blanching3) Pasteurization4) Sterilization

FOOD IRRADIATION

Food irradiation involves the use of either high-speed electron beams or high-energy radiation (e.g., X rays and gamma rays). Radiation destroys microorganisms by changing the structure of cell membranes.

DEHYDRATION

-The water content of foods can be controlled by removing water through dehydration. Loss of moisture content produced by drying results in increased concentration of nutrients in the remaining food mass.

-Reduces the bulk weight.

NATURAL AND CHEMICAL PRESERVATIVES

Food preservatives are substances which under certain conditions delay the growth of microorganisms without necessarily destroying them.NATURAL PRESERVATIVE- salt, sugar, vitamins C.CHEMICAL PRESERVATIVE – benzoic acid, butylated hydroxyanisole (BHA).

References

-INDUSTRIAL MICROBIOLOGY BY A H PATEL -FUNDAMENTAL OF MICROBIOLOBY BY EDWARD ALCOMO (4TH EDITION) -www.britannica.com

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