1. fully the principles of food sanitation. One must understand the role of microorganisms in food spoilage and poisoning. Microorganisms are found throughout the natural environment. These microorganisms （also called microbes） cause food spoilage through ingestion of food， which contains microorganism's food borne infection because certain disease con microorganisms of public health concern.
3. Microorganisms are also important in connection with food sanitation because certain disease-producing microbes may be transmitted through food. The importance of sanitation practices is to combat the proliferation and activity of food spoilage and food poisoning microorganisms.  The microorganisms most common to food are bacteria and fungi. The fungi， which are less common than bacteria， consist of two major microorganisms， molds and yeasts.
4. Molds are multicellular microorganisms with mycelial （filamentous） morphology. These microbes are also characterized by their display of a variety of colors and generally recognized by their mildewy or fuzzy， cotton like appearance. Molds can develop numerous
values翻译tiny spores that are t found in the air and can be spread by air currents. These spores can produce new mold growth if they are transferred to a location that hears conditions conductive to germination.
5. Mold generally withstands greater fluctuation in PH than bacteria and yeasts and can frequently tolerate more temperature fluctuation. Although molds thrive best at or near a PH of 7.0，a PH range of from 2.0 to 8.0 can be tolerated at ambient temperature than in a colder environment， even though an acid to neutral PH is preferred. Molds thrive better at ambient temperature than in a colder environment ，even though  growth  can occur below 0℃。
6. Although mold growth is optimal at a water activity （Aw） of approximately 0.85，growth can and does occur below 0.80 .at an Aw of 0.90 or higher， bacteria and yeasts grow more effectively and normally utilize available nutrients for growth at the expense of molds. When the Aw goes below 0.90 molds grow more growth. Yeasts are generally unicellular and differ from bacteria in their larger cell size and morphology，and because they produce buds during the process of reproduction by division.
7. Like molds， yeasts can be spread through the air， or other means， and alights on the surface of foodstuffs. Yeast yeasts prefer an Aw of 0.90-0.94，but can grow below 0.90. These microorganisms grow best in the intermediate acid range； a PH of from 4.0 to 4.5 foods that highly contaminated with yeasts will frequently have a slightly fruity odor.
8. Bacteria are unicellular microorganisms that are approximately 1 \m in diameter with morphology variation from short and elongated rods （bacilli） to spherical or ovoid forms， Cocci are spherically shaped bacteria. Individual bacteria closely combine in various forms according to genera. Some sphere-shaped bacteria occur in clusters similar to a bunch of grapes （i.e.， staphylococci）。
9. Other bacteria （rod shaped of sphere shaped） are linked together to form chains （i.e.， streptococci）。 Certain genera of sphere-shaped bacteria also are formed together in pairs （diploid formation； i.e.， pneumococci） or as a group of four （tetrad formation； i.e.， sarcinia）， while other genera appear as an individual bacterium. Other bacteria possess flagella and are motile. Bacteria produce various pigments， which range from shades of yellow to dark pigments such as brown or black.
  10. Certain bacteria have pigmentation of intermediate colors such as red， pink， orange， blue green， or purple. These bacteria cause food discoloration， especially among foods with unstable color pigments such as meat. Some bacteria also cause discoloration by slime formation.  Some species of bacteria also produce spores. The properties of which vary considerably. Certain spores are resistant of heat， chemicals， and other adverse environmental conditions.
  11. Many of these spore-forming bacteria are thermophilic microorganisms， which produce a toxin that will cause food poisoning.
  Methods of Killing Microorganisms
Before assessment of methods available for d3estruction of microorganisms， it is important to define death as applied to microorganisms. Microorganisms are considered dead when they cannot multiply， even after being in a suitable growth medium under favorable environmental conditions.

版权声明：本站内容均来自互联网，仅供演示用，请勿用于商业和其他非法用途。如果侵犯了您的权益请与我们联系QQ:729038198，我们将在24小时内删除。