Imoact Preservation Techniques On Nutrition

Question 1

Pickling

Answer 1

Vegetables and other foods are stored in sterilised jars to which vinegar is added. The pickles are left to mature; pickled vegetables become crisp in texture.
The acid prevents the growth of microbes.

Examples of foods preserved by this method
• Vegetables, e.g. onions, shallots, cauliflower, gherkins, cucumbers, peppers, hard boiled eggs, fish, e.g. herring.

Effects on nutrient stability
• Some riboflavin (B2) may be destroyed by the action of light through clear-glass storage jars.

Question 2

Drying

Answer 2

Water is driven out of foods either by being laid out in the sunshine or by method exposure to warm, dry air or in a drier.

The foods shrivel and dry out as the
water evaporates from them. foods change colour and texture and their flavour becomes more concentrated.

Microbes cannot grow in the dehydrated
foods without moisture.

Examples of foods preserved by this method
Fruits, vegetables and fish

Effects on nutrient stability
• Vitamin A is destroyed by heat and air
• Vitamin C and many B vitamins are destroyed by this process

Question 3

Salting

Answer 3

Salt is added to foods to
remove moisture from microbes by osmosis (the movement of water molecules from a high water concentration to a low water concentration through a semipermeable membrane), which destroys them.

Examples of foods preserved by this method
• Meat, fish, some vegetables, e.g. green beans.

Effects on nutrient stability
• Sodium content of food is increased.

Question 4

Curing

Answer 4

Carried out by exposing foods to wood smoke, which adds chemicals to the food that preserve it. Foods such as meat (e.g. pork to make bacon and ham) are
‘cured’ first by the addition of salt, nitrates and nitrites, which prevent the growth of a particularly dangerous pathogenic bacteria called Clostridium botulinum and other microbes.

Examples of foods preserved by this method
• Meat, fish, cheese.
Effects on nutrient stability
• Some denaturation of protein.