Food Preservation
Food Preservation
Food Preservation
Food Preservation
Food Spoilage
Biological Changes Yeast: A fungus (a plant that lacks chlorophyll) that is able to ferment sugars and that is used for producing food products such as bread and alcohol. Fermentation: The conversion of carbohydrates to carbon dioxide and alcohol by yeast or bacteria.
Food Spoilage
Chemical Changes Chemical reactions or changes also contribute to food deterioration. Enzymes play a significant role in catalyzing these reactions and can be categorized by the substance on which they act (substrate) or their mode of action. An example: Proteases, also called proteolytic enzymes, split proteins into smaller compounds.
Food Spoilage
Physical Changes The most common physical changes occurring in foods as they spoil are evaporation, drip loss, and separation. Dehydrate: To remove at least 95% of the water from foods by the use of high temperatures. Freeze-dry: To remove water from food when it is in a frozen state, usually under a vacuum.
Drying is the food preservation process that consists of removing the foods water, which effectively inhibits the growth of microorganisms. Like:
Sun
Drying
http://www.mountainhouse.com/
Sublimation: The process in which a solid changes directly to a vapor without passing through the liquid phase.
Cure: To preserve food through the use of salt and drying. Sugar, spices, or nitrates may also be added. Fermentation Pickling uses vinegar to preserve foods. Edible coating: Thin layer of edible material such as natural wax, oil, petroleum-based wax, etc. that serves as a barrier to gas and moisture.
Carbohydrates are required for the fermentation process. Throughout Asia, vegetables are still commonly fermented. In North America, foods most often preserved by fermentation are cucumbers, olives, and cabbage.
the food is prepared by being packed into containers, which are then sealed.
Then
the containers are canned, or heated to ensure that all microorganisms are destroyed.
Pressure cooker
Canner
Cold Preservation
Refrigeration slows down the biological, chemical, and physical reactions that shorten the shelf life of food. For safety purposes, refrigerators should be kept between just above freezing to no more than 40F (4C). All perishable foods should be refrigerated as soon as possible, preferably during transport, to prevent bacteria from multiplying.
Cold Preservation
Freezing makes water unavailable to microorganisms. The chemical and physical reactions leading to deterioration are slowed by freezing. Rancid: The breakdown of the polyunsaturated fatty acids in fats that results in disagreeable odors and flavors. Freezer burn: White or grayish patches on frozen food caused by water evaporating into the packages air spaces.
Heat Preservation
Pasteurization: A food preservation process that heats liquids to 160F (71C) for 15 seconds, or 143F (62C) for 30 minutes, in order to kill bacteria, yeasts, and molds.