Food Preservation

FOOD PRESERVATION 1.Food preservation is a process that makes food last longer. 2.Food preservation makes food last longer by delaying it from becoming bad. 3.Food preservation is very important because : a)It makes food last longer b)It kills bacteria and fungi c)It can slow down the activity of disease-causing bacteria. 1.We can preserve food by killing bacteria and fungi besides preventing oxidation. 2.We can make the environment unsuitable for microorganisms to live in. 3.We preserve food by a)keeping it dry b)keeping it hot or frozen c)keeping it airtight 7. Food can preserved in several ways.

DRYING/DEHYDRATION 1)We can dry food to preserve it (to make the food last longer). 2)Drying involves the removal of water from food substances. 3)We can dry food by : a)Drying the food under hot sun . Examples :- prawns, squid, vegetables, chillies and anchovies. b)Heating it in the oven. Heating food to a high temperature. Examples : meat and biscuit. c)Heating it with a flame. Examples: tea leaves, coffee powder and milk powder. 4)Without water and food, bacteria and fungi cannot grow. 5)This can make the food last longer. 6)Examples of food preserved by drying are fish, prawns, cuttlefish and fruits.

ADVANTAGES AND DISADVANTAGES OF DRYING Advantages A cost effective method of food preservation Food last longer

Disadvantages Most of the nutrients in the food are destroyed. The taste of the food is no longer the same

REFRIGERATING i.Cooling 1)Food can be preservde by storing them in a cool place below the room temperature such as putting them in a place that is between 0ºC to 5ºC in a refrigerator. 2)In a cool condition, bacteria become inactive ( slow bacteria action) and do not reproduce or give off poisonous gases. It does not kill the bacteria, but it slows down their growth. 3)Bacteria and fungi become active again when the food is taken out from the refrigerator.Therefore, after taking out food from refrigerator, it must be cooked or eaten quickly before its spoil. 4)Cooling still retain the texture of the food. 5)Examples of food preserved by cooling are vegetables, fruits, eggs and milk. 6)Cooling can be done by keeping the food in a refrigerator at home. ADVANTAGES AND DISADVANTAGES OF COOLING/ REFRIGERATING Advantages Allows perishable food such as fruits and vegetables to be kept longer.

ii.Freezing

Disadvantages Food preserved this way cannot be brought along while traveling.

1)We can preserve food by keeping it frozen. 2)Food is kept frozen at a temperature of -10°C. 3)Food can last longer because bacteria and fungi cannot grow at a very low temperature. The microorganisms become inactive. 4)Freezing preserves the quality and nutrient content of the food. 5)Foods that can be preserved by freezing are chicken, meat, prawns and cuttlefish.

ADVANTAGES AND DISADVANTAGES OF FREEZING Advantages The taste and nutritional value of the food is preserved There is no change in size, shape and colour of the food

VACUUM-PACKAGING

Disadvantages Microorganisms become inactive only. They become active again at room temperature.

1)Vacuum-packaging is the preservation of food by sealing it in a pack after air has been removed. 2)The food is kept in airtight packages. 3)Microorganisms cannot survive without air as they require air for respiration. 4)Airtight packages are packages where all the air has been expelled out. 5)Foods suitable for vacuum packing include sausages, coffee powder, biscuits, peanuts, vegetables and fruits. The steps involved in vacuum packing

ADVANTAGES AND DISADVANTAGES OF VACUUM PACKAGING Advantages Disadvantages The quality of food is It is suitable only for certain food maintained It needs a special and expensive Food can be transported from equipments. one country to another

PICKLING

1)Pickling is done by soaking or keeping food in vinegar, salt solution or sugar solution. 2)Pickling reduces the water content of food. This prevents the growth of bacteria and fungi. 3)Food preserved by pickling will last longer. 4)However, its taste and nutrient content will be different. 5)Food that can be reserved by pickling are fruits and vegetables.( unripe papaya, and chilies) 6)Microorganisms cannot grow under acidic conditions. ADVANTAGES AND DISADVANTAGES OF PICKLING Advantages Fruits and vegetables can be preserved.

Disadvantages Food experiences a change in taste and colour. Nutritional value is changed. May affect health, cause diabetes or high blood pressure.

CANNING

1)We can also preserve food by putting it in airtight cans 2)Food can last very long if kept in airtight cans 3)The food is cooked and all the air is expelled from it before canning 4)Bacteria and fungi cannot grow without air. 5)Food suitable to be preserved this way includes fish, meat, fruits and vegetables. ADVANTAGES AND DISADVANTAGES OF BOTTLING AND CANNING Advantages Portable, canned food can be taken anywhere easily

Disadvantages Flavour of food is changed. Preservatives are added to the food

Food can be easily prepared for consumption.

Nutrient content is low

PASTEURISATION 1)Pasteurisation can destroy microorganisms in milk, ice-cream and fruit juice. 2)During pasteurization, the food is heated quickly for a few second. 3)Milk is pasteurized by heating it in 72 °C for fifteen second or at 65°C for 30 minutes. 4)Pasteurisation still retain the original flavour and taste of the food. ADVANTAGES AND DISADVANTAGES OF PASTEURISATION. Advantages The nutritional value and quality of the milk is maintained The taste is unchanged

Disadvantages Food cannot be kept long once the bottle is opened

IRRADIATION 1) Irradiation is able to kill bacteria without significantly changing the food containing the bacteria. 2) If you seal food in plastic and then radiate it,the food will become sterile and can be stored on a shelf without refrigeration ADVANTAGES AND DISADVANTAGES OF IRRADIATION Advantages The food texture is not changed

Disadvantages It reduces the content of several key nutrients. Is ineffective against viruses.

FERMENTATION 1)Food could be preserved via fermentation. 2)In fermentation, yeast is added to fruit juice or other substances. 3)This process produces ethanol which stops the activity of microorganisms. ADVANTAGES AND DISADVANTAGES OF FERMENTATION Advantages The food texture is not changed

Disadvantages It reduces the content of several key nutrients. Is ineffective against viruses.

FREEZE-DRYING 1)Freeze-drying works by freezing the material and then reducing the surrounding pressure and adding enough heat to allow the frozen water in the material to sublime directly from the solid phase to gas. ADVANTAGES AND DISADVANTAGES OF FREEZE-DRYING Advantages Does not cause shrinkage or toughening of the food dried The food's taste and smell remain unchanged

Disadvantages It is an expensive process.

FOOD ADDITIVES 1)A food additive is any substance added to food. 2)Sugar, salt, and corn syrup are the most commonly used food additives. 3)Food additives keep foods fresh, slow microbial growth, give desired texture and appearance, aid in processing and preparation. ADVANTAGES AND DISADVANTAGES OF FOOD ADDITIVES Advantages Help assure availability of wholesome, appetising, and affordable that meet consumers' demand. Help prevent food poisoning

Disadvantages May be used.to make bad food look like good. Many people are allergic to certain additives

BIOLOGY FORM 4 FOOD PRESERVATION

NAME : RUBAN A/L SELVARAJAH CLASS : 4 ELIT TEACHER : PN. RAJESWARY