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We all know that microbes
are involved in food spoilage and food poisoning. What is less known
is that besides these harmful bacteria (pathogens) there are also beneficial
micro-organisms essential to our existence, and which add taste and
variety to our diets.
Microbes are often thought of only as dangerous germs and little else.
The fact that many of them help us in a multiplicity of ways, usually
goes unnoticed. As well as aiding our digestion for example (the human
gut is home to many billions of helpful microbes), they figure prominently
in our daily diets.
Fermented foods are those in which desirable changes have been produced
by the action of microbes. Over 3,500 traditional, fermented foods exist
world-wide. They include the breads, yoghurts and cheeses familiar in
Europe and North America, while in Africa foods made from fermented
starch crops (such as yams or cassavas) are an important part of the
local diet. In Asia, products derived from fermented soya beans or fish
are consumed daily. Fermented drinks include not only alcoholic beverages,
but also tea, coffee and cocoa, where the leaves or beans are fermented
after harvesting, developing the characteristic flavours. Fermentation
can make food more nutritious, tastier or easier to digest. It can also
enhance food safety because it helps to preserve food and increase its
shelf life, reducing the need for refrigeration or other energy intensive
preservation methods.
Yeast is the most familiar microbe associated with food and drink. It
is used in making bread, where it plays a major part in producing the
spongy texture, and alcohol, which it ferments from sugars. Its use
in these and other processes doubtless began by chance, but nowadays
yeast cultures are prepared and added in a controlled way in food production
processes. The huge industrial importance of yeast led to more than
600 scientists from 96 laboratories around the world collaborating on
the Yeast Genome Project. This culminated in the publication of the
complete genetic sequence of Saccharomyces cerevisiae (bakers yeast)
in 1997.
The manufacture of cultured dairy products represents the second most
important fermentation industry (after the production of alcoholic drinks).
For instance, cheese is made in almost every country. This fermentation
facilitates the conversion of the milk sugar, lactose, into lactic acid
by lactic acid bacteria. This process contributes to flavour development
and has a major role in preventing spoilage and the growth of pathogenic
organisms. Again, the role of microbes in producing dairy products has
evolved from a chance discovery to a highly elaborated process involving
the production of specialised 'starter' cultures. Today, a major challenge
for the dairy fermentation industry is to provide stable strains of
bacteria that function consistently in large-scale industrial fermentations.
There are many opportunities for using lactic acid bacteria in other
ways. These include their use as beneficial bacteria in probiotic cultures,
ones that supplement and help our normal gut bacteria to function more
efficiently. The world-wide market for these products continues to increase
in response to the demands of an increasingly health-conscious public.
Microbes are involved in the production of many other foods and they
are sometimes used as food themselves.  |
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