Spoilage
Spoilage refers to the process of deterioration in food , which is associated with a significant deterioration in quality (color, consistency, smell, taste) through natural processes. The term is to be distinguished from food poisoning , in which pathogens or toxins produced by them get into the food. A spoiled food does not necessarily have to be harmful to health.
Food spoilage is caused by decomposition processes caused by bacteria , fungi and the enzymes contained in the food . Physical influences such as light, cold ( freezer burn ) and heat as well as chemical reactions such as peroxide formation ( becoming rancid ) and oxidation can lead to food spoilage.
Microbial spoilage
Microorganisms break down many organic substances, which causes food to spoil. Metabolic end products of bacteria , yeasts , molds and other microorganisms include organic acids , alcohols , ketones , amino acids , vitamins , ammonia , antibiotics and toxins . Microbial toxins are often the cause of acute illness from food. The presence of the microorganisms not only leads to the enrichment of the food with metabolic products , but also to the loss of the ingredients . This causes the product to change its appearance, smell and also its original taste .
Methods for preserving food against microbial spoilage or for combating infectious diseases make use of the physiological peculiarities and differences of bacteria and other microorganisms compared to humans.
Enzymatic spoilage (chemical spoilage)
Enzymes are proteins formed in living cells that act as biocatalysts to accelerate the chemical reactions of the metabolism and therefore also lead to food spoilage. Changes caused by enzymes can be triggered both by the product's own enzymes ( autolysis ) and by external enzymes . By enzymatic and non-enzymatic food browning occurs brown discoloration in food. This can be prevented by heating ( pasteurization ), lowering the pH value by adding acids or by adding inhibitors. The hydrolytic breakdown of carbohydrates, fats and proteins as well as oxidative changes of fats and vitamins are often responsible for the spoilage.
Physical spoilage
Processes that are caused by the effects of temperature , light and mechanical stress are considered physical spoilage . Freezer burn is an example.
