Different Food Preservation Practices
FOOD PRESERVATION
Food is preserved to prevent natural and microbial decay, by modifying the conditions that favour enzyme activity and the growth of micro-organisms.
Foods are preserved for the following reasons:
1. To add variety to the diet, by making food available out of season.
2. To make use of food when it is cheap and plentiful and to store it for later use.
3. To vary the diet by preserving food in ways the make a new product out of the food (e.g. pickling, jam making).
METHODS OF PRESERVATION
1) Heating – To destroy micro-organisms and enzyme activity.
2) Removal of moisture- To inhabit microbial growth.
3) Removal of air- To prevent further entry of micro-organisms.
4) Reduction of temp. - To inhabit microbial and enzymatic activity.
HEAT PRESERVATION
Most bacteria, yeasts, moulds, and enzyme are destroyed by heating at 100 degrees C. However, some bacteria and bacterial spores are resistant to such temperatures and higher temperatures are required to destroy them.
The main methods of heat treatment are:
1) Sterilization.
2) Pasteurization.
3) Canning and bottling.
STERILIZATION
Nicolas Appert, discovered that if food was heated in a sealed container at a high temperature, it would remain edible and free from decay for some time, unless the seal was broken. This is because prolonged heating will destroy harmful micro-organisms, which are naturally present in the food, and the food will only start to decay when new organisms contaminate it. Uses of heat sterilization:
1) Milk.
2) Canned or bottled foods.
Effects on the nutritive value:
The heat-sensitive vitamins thiamin and vitamin C (ascorbic acid) are destroyed to a large extent.
PASTEURIZATION
Sterilization was used to destroy pathogenic and souring microbes, but Louis Pasteur discovered that there was a way to do using less sever heat treatment and without
Food is preserved to prevent natural and microbial decay, by modifying the conditions that favour enzyme activity and the growth of micro-organisms.
Foods are preserved for the following reasons:
1. To add variety to the diet, by making food available out of season.
2. To make use of food when it is cheap and plentiful and to store it for later use.
3. To vary the diet by preserving food in ways the make a new product out of the food (e.g. pickling, jam making).
METHODS OF PRESERVATION
1) Heating – To destroy micro-organisms and enzyme activity.
2) Removal of moisture- To inhabit microbial growth.
3) Removal of air- To prevent further entry of micro-organisms.
4) Reduction of temp. - To inhabit microbial and enzymatic activity.
HEAT PRESERVATION
Most bacteria, yeasts, moulds, and enzyme are destroyed by heating at 100 degrees C. However, some bacteria and bacterial spores are resistant to such temperatures and higher temperatures are required to destroy them.
The main methods of heat treatment are:
1) Sterilization.
2) Pasteurization.
3) Canning and bottling.
STERILIZATION
Nicolas Appert, discovered that if food was heated in a sealed container at a high temperature, it would remain edible and free from decay for some time, unless the seal was broken. This is because prolonged heating will destroy harmful micro-organisms, which are naturally present in the food, and the food will only start to decay when new organisms contaminate it. Uses of heat sterilization:
1) Milk.
2) Canned or bottled foods.
Effects on the nutritive value:
The heat-sensitive vitamins thiamin and vitamin C (ascorbic acid) are destroyed to a large extent.
PASTEURIZATION
Sterilization was used to destroy pathogenic and souring microbes, but Louis Pasteur discovered that there was a way to do using less sever heat treatment and without