Download Food Poisonings in Hong Kong—Hazards and Prevention

Use of Microbes for Food and Food Production
Kwan Hoi Shan
Department of Biology, Food and Nutritional Sciences Programme, CUHK
You may not be aware that mushrooms such as Xianggu, button mushroom,
truffle, morel, and jelly mushroom, are microorganisms. They are big and may not
look “micro” to you. However, in fact, they are fungi and are always included in the
fields of microbiology, microbial biotechnology, etc. On the other hand, you may be
aware that many of our daily foods and food products are also produced using
microorganisms—so-called “fermented foods”. Human has been making fermented
food and beverages since thousands of years ago. The term “fermentation” would
bring fermented alcoholic beverages to our minds. We, however, should note that
“fermentation” means different things to different people and in different fields. In
basic microbiologist usage, fermentation refers to an energy metabolism in anaerobic
condition. In industrial usage, fermentation refers to the growth of microbes on a
large scale to obtain specific products. For food scientist, fermentation is used in
context of fermented foods, the process of making a food in which the characteristic
properties are the result of extensive microbial growth. We are here, of cause,
looking at fermentation as food scientist. The fermentation of foods serves many
purposes for our pleasure, convenience, and health. The foods after fermentation
may become more easily digested, have better taste, flavor, aroma, and nutrient, and
can be stored longer.
Microbial growth on foods makes fermented foods, but also spoils foods. It is
a matter of taste, preference, and culture, of people that a certain microbial growth
on a food would be considered a delicacy or a rotten food. In deed, a delicious
fermented food such as yogurt may be thrown away by your grandma, thinking that
it is spoiled milk.
Common fermented foods are discussed here. Simple fermentations involve
the production of lactic acid or alcohol from simple sugars by lactic acid bacteria or
yeasts. Examples are production of yogurt and wine. More complex fermentations
require degradation of complex carbohydrates such as starch by hydrolases into
simple sugars first. Simple sugars are then converted to simple organic compounds
by bacteria, yeasts, or both. Such processes produce soy sauce, miso, and beer.
Some fermented foods and beverages are produced by very complex and poorly
understood processes. Teas, coffees, and shrimp paste belong to this group.
You may be amazed to learn that so much common foods and beverages are
the results of the action of the lowly microorganisms which we sometimes try so
hard to get rid of.
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References
1. The Biotechnology CD-ROM provided by the Education Department contains
much information on food and beverage fermentation products and processes.
2. Information about food production using microbes can be found in the following
web sites.
a.
http://www.foodbiotech.org/
 “The Food Biotechnology Communications Network (FBCN) is
becoming Canada's leading information source for balanced,
science-based facts about food biotechnology and its impact on our
food system”
b.
http://food.epicurious.com/
 “The taste of the Web. Online host to Gourmet and Bon App*tit
magazines. Recipes, menus, drink suggestions, forums on food and
cooking.. . ."
c.
http://commtechlab.msu.edu/sites/dlc-me/zoo/
 Look at the Microbial Zoo which has interesting information on
several aspects of microorganisms.
d.
http://www.pacificcoast.net/%7Emycolog/chapter18.htm
 An electronic textbook of mycology. Lots of pictures to look at.
Chapter 18 is Fungi as Food.
e.
http://www.pacificcoast.net/%7Emycolog/chapter19.htm
 Ditto. Chapter 19 is Food Production using Fungi
f.
http://www.ditto.com/
 Search engine searching the internet for pictures. You can get nice
pictures of bacteria, fungi, and foods using this search engine.
g.
http://biology.about.com/education/biology/
 "The starting place for exploring Biology". Check on the parts of
Microbiology and Fermentation.
h.
http://tea.hypermart.net/manu/green.html
Lots of information about tea.
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