2. 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.
3. 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.
4. 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.
5. Food Preservation Methods Drying is the food preservation
process that consists of removing the foods water, which
effectively inhibits the growth of microorganisms. Like: Sun
Drying
6. Food Preservation Methods Commercial Drying The most
important types of commercial drying are: Conventional: heat.
Vacuum: pulls the water out. Osmotic: water drawn out by osmosis.
Freeze-drying: ice crystals vaporize.
7. http://www.mountainhouse.com/
8. Food Preservation Methods Sublimation: The process in which
a solid changes directly to a vapor without passing through the
liquid phase.
9. Food Preservation Methods 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.
10. Food Preservation Methods 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.
11. Food Preservation Methods The purpose of edible coatings is
fourfold: 1. To increase shelf life by acting as a barrier to
moisture, oxygen, carbon dioxide, volatile aromas, and other
compounds whose loss would lead to deterioration. 2. To impart
improved handling characteristics, such as the ability to bend more
easily without breaking. 3. To improve appearance through increased
gloss and color. 4. To serve as a vehicle for added ingredients
such as flavors, antioxidants, antimicrobials, etc.
12. Food Preservation Methods Canning is a two-step process:
First 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. Sterilization: The
elimination of all microorganisms through extended boiling/heating
to temperatures much higher than boiling or through the use of
certain chemicals.
13. Pressure cooker Canner
14. 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.
15. 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.
16. 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.