Food spoilage and preservation.
A4 FOOD SPOILAGE AND PRESERVATION
References/Resources: Food Facts page 81-82
The Science of Food page 213-234
Cooking explained 3rd edition page 207-209
FOOD SPOILAGE
A.4.1 food spoilage Food becoming unfit for consumption, for example, due to chemical or biological contamination.
Most natural foods have a limited life. Perishable food such as: fish, meat, milk and bread have a short lifespan. Other foods keep a considerably longer time but decompose eventually. There are many causes of food spoilage. Enzymes within some foods bring about their destruction, while chemical reactions such as oxidation and rancidity decompose others – but the main single cause of food spoilage is invasion by microorganisms such as moulds, yeasts and bacteria.
Micro-organisms are found everywhere, since the conditions which bring about their growth are readily available. Like humans, they prefer a warm, moist environment, a supply of oxygen and food – and because their nutritional requirements are similar to ours, they readily contaminate our food supplies. When food spoilage is caused by the growth of yeasts and moulds it is self-evident: a furry growth covers the food and it becomes soft and often smells bad. Bacterial contamination is more dangerous because very often the food does not look bad: even though severely infected, it may appear quite normal. The presence of highly dangerous toxins and bacterial spores is often not detected until after an outbreak of food poisoning, when laboratory examination and experiments uncover the infecting agent.
A.4.2 TYPES OF FOOD SPOILAGE
PHYSICAL SPOILAGE: Physical damage to the protective outer layer of food during harvesting, processing or distribution increases the chance of chemical or microbial spoilage. Examples of physical spoilage include:
•
•
•
•
Staling of bakery products and components
Moisture migration between different components
Physical separation of components or ingredients
Moisture
References/Resources: Food Facts page 81-82
The Science of Food page 213-234
Cooking explained 3rd edition page 207-209
FOOD SPOILAGE
A.4.1 food spoilage Food becoming unfit for consumption, for example, due to chemical or biological contamination.
Most natural foods have a limited life. Perishable food such as: fish, meat, milk and bread have a short lifespan. Other foods keep a considerably longer time but decompose eventually. There are many causes of food spoilage. Enzymes within some foods bring about their destruction, while chemical reactions such as oxidation and rancidity decompose others – but the main single cause of food spoilage is invasion by microorganisms such as moulds, yeasts and bacteria.
Micro-organisms are found everywhere, since the conditions which bring about their growth are readily available. Like humans, they prefer a warm, moist environment, a supply of oxygen and food – and because their nutritional requirements are similar to ours, they readily contaminate our food supplies. When food spoilage is caused by the growth of yeasts and moulds it is self-evident: a furry growth covers the food and it becomes soft and often smells bad. Bacterial contamination is more dangerous because very often the food does not look bad: even though severely infected, it may appear quite normal. The presence of highly dangerous toxins and bacterial spores is often not detected until after an outbreak of food poisoning, when laboratory examination and experiments uncover the infecting agent.
A.4.2 TYPES OF FOOD SPOILAGE
PHYSICAL SPOILAGE: Physical damage to the protective outer layer of food during harvesting, processing or distribution increases the chance of chemical or microbial spoilage. Examples of physical spoilage include:
•
•
•
•
Staling of bakery products and components
Moisture migration between different components
Physical separation of components or ingredients
Moisture