Food preservation by fermentation is an ancient method that can increase a food's shelf life and microbiological safety. Fermentation can also make some foods more digestible and reduce toxicity.  Fermentation is a chemical process that eliminates or slows down food spoilage by changing its chemical makeup. Other natural preservation processes include salting, smoking, and dehydration.  Here are some principles of food preservation by fermentation: Temperature: Fermentation occurs between 70–75°F. Temperatures above this range can cause spoilage, while temperatures below this range can... Show more

Food preservation by fermentation is an ancient method that can increase a food's shelf life and microbiological safety. Fermentation can also make some foods more digestible and reduce toxicity. 
Fermentation is a chemical process that eliminates or slows down food spoilage by changing its chemical makeup. Other natural preservation processes include salting, smoking, and dehydration. 

Here are some principles of food preservation by fermentation:
Temperature: Fermentation occurs between 70–75°F. Temperatures above this range can cause spoilage, while temperatures below this range can prevent fermentation and spoilage.
pH: The fermentation process can lower the pH of food to levels below 4. This drop can inhibit many acidophiles.
Freezing: Freezing can stop the fermentation process. While some probiotics may be lost, the enzymes and acids should survive.
Vacuum packing: Vacuum packaging can slow the growth of bacteria that need oxygen to proliferate. It can also prevent the input of oxygen and microorganisms that can lead to food deterioration and contamination. 

Related: Food Engineering Practice Test: Principles of Food Preservation by Canning and Drying and Principles of Food Concentrates

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