TECHNOLOGICAL DEVELOPMENT IN

FOOD PROCESSING

• Food processing is the process of preparing food to make it more attractive, more palatable and to last longer

• Food has to be processed so that it can withstand long periods of transportation and storage

•One of the main purpose of food processing is to preserve food by overcoming the factors that cause food spoilage

• Food spoilage is caused by : *the action of microorganism in food,

especially decomposing bacteria and fungi which act on carbohydrates and proteins in food to produce carbon dioxide, water, ammonia, hydrogen sulphide and other organic substances. The presence of these substances spoil the food and sometimes make it toxic

• The oxidation of food due to the oxygen reacting with enzymes and chemical released by the cells in the food. Oily food can also become rancid, smell and taste different as a result of oxidation. Rancid food is harmful to the body

• Food has to be processed : *to extend their lifespan so that

they can be stored for future use *to avoid wastage *to prevent the spread of diseases

due to contamination of food, which can cause food poisoning

*to ensure there will be the continuous supply of food for the population

*to increase their commercial value *to prevent the bacteria and fungal

decay *so that they can withstand long

periods of transportation and storage *so that food can be supplied to the

local or global market all year round in good condition

• To diversify the uses of food substances. For example , milk has been processed to produce a variety of dairy products such as cheese, yogurt, ice cream, butter and chocolates

RELATING THE FOOD PROCESSING METHODS

WITH FACTORS CAUSING FOOD SPOILAGE Microorganisms require nutrients,water,oxygen and a suitable

temperature for optimal growth and reproduction

Microorganisms can only survive in condition with optimum pH and solute concentrations as these will not destroy them

Hence,food can be preserved by destroying the microorganisms present in the food or by stopping their activities

A few methods of processing and preserving food that have been practised since the early days are cooking,fermentation and drying of food

COOKING• Cooking at high temperatures or boiling for

at least five minutes

• Heating food to high temperatures can kill microorganisms and denature the enzymes that cause the breakdown of food.

• Certain bacterial spores may also be killed. However toxins produced by bacteria are not always destroyed.

• E.g. Meat, vegetables and fish

FERMENTATION PROCESS

• Yeast is added to fruit juices or other food substances.

• Fermentation produces ethanol which at high concentrations, stops the activity of bacteria that causes food spoilage.

• The ethanol produces also has a great commercial value.

• E.g. Fruit juices and tapai.

DRYING• Drying under the hot sun, in hot air or in the

oven.• Drying removes water from food. This

prevents microorganisms from growing as microorganisms cannot live without water.

• The enzymatic activity in food also stops.• The ultraviolet rays from the sun also kill

bacteria and many other harmful microorganisms.

• E.g. Fish, meat and fruit

PICKLING FOOD• Food is soaked in an acidic solution

such as vinegar.

• Most organisms cannot lives in low pH conditions.

• E.g. Chillies, ginger, onions and mangoes

TREATING FOOD WITH SALT AND SUGAR

• Food is soaked in a concentrated salt solution or boiled with sugar.

• Microorganisms lose water through osmosis in a hypertonic solution.

• E.g. Meat, vegetables and ducks’ eggs

Milk is preserved by pasteurisation to destroy bacteria which cause diseases such as those which cause tuberculosis and typhoid.

In this process,milk is heated toa) 63 for 30 minutesb) 72 for 15 seconds and then rapidly cooled to below 10

While maintaining the nutrient content The purpose of pasteurisation is to kill microorganisms and natural flavour of the milk

Nutrient like vitamin B are not destroyed. Pasteurisation is unable to kill all types of

bacteria.Therefore,pasteurised milk needs to be stored in the refrigerator because of its short shelf life.This is to prevent those microorganism active again.

Fruit juices and soup can also preserved using this method.

Canning uses the heat sterilisation method to kill microorganism and their spores.

The food is packed in cans and steamed at a high temperature and pressure to drive out all the air.

The cans containing food are then sealed while the food is being cooled.

The airtight containers all the vacuum created within the cans prevent the growth of microorganisms.

Pathogens and food-spoiling bacteria are destroyed and the enzymes in the food are inactivated.

Canning keeps food sterile for long periods hence,the shelf life of canned food is usually longer although the cans may eventually corrode.

However,if the food is not thoroughly cooked,there is a danger contamination by spores of Clostridium botulinum.

This bacteria can survive in food which is mildly heated and stored at room temperature.Under these conditions,the bacteria produce a toxin which can kill human at very low concentrations.

Consequently,because canned food needs to be thoroughly cooked,it is low in quality.

Refrigeration is a common method used by household to prevent food spoilage.

Food stored at temperatures below 0 can remain fresh for a long period of time.

Meat,fish and meat products can be preserved this way.

The extremly low temperatures prevent growth of microorganisms or germination of spores because enzymatic reactions stop at low temperatures.