DEPARTMENT: FOOD
SCIENCE AND TECHNOLOGY
FACULTY: AGRICULTURAL AND NATURAL RESOURCE
MANAGEMENT (FARM)
COURSE CODE: FST
122
COURSE TITLE: PRINCIPLES
OF FOOD MICROBIOLOGY
TABLE OF CONTENTS
Dedication
Table
of contents
Introduction
Roles
of microorganism in food industries
Different
industries and roles of microorganism in them
Baking
industry
Bacteria
in baking industry
Mold
in baking industry
Wine
industry
Conclusion
INTRODUCTION
There are various types of
microorganism that are used for large scale production of industrial items. For
example corynebacterium species which are often used to mass produce amino
acids utilized in food processing.
The ability of specific
microorganisms to produce specialized enzymes and protein has been exploited
for many purposes in industry-industrial microorganisms are used to produce
many things, including food, cosmetics, pharmaceuticals and construction material,
but here we are going to specialize on the roles of microorganisms in the food
industries.
ROLES OF MICROORGANISM IN THE FOOD
INDUSTRIES
Microorganism are essential for the
production of foods such as cheese, yogurt, other fermented food like bread,
bear, wine, microorganism like yeast, especially saccharomyces cerevisiae, is
used to leave bread, brew beer, and make wine, certain bacteria including
lactic acid bacteria are used to make yogurt, cheese, hot-sance, pickles
fermented sausages and dishes such as kimchi.
The common effect of these
fermentation is that the food product is less hospitable to other microorganism
including pathogens and spoilage causing microorganisms, thus extending the
food’s shelf life.
Some microorganisms are used to manufacture
food or to increase the quantity of industrial products. Numerous
microorganisms are used within industrial microbiology. These include naturally
occurring organisms, laboratory selected mutants, or even genetically modified
organisms (GMO) in food sources is gaining both momentum, with more and more
supporters on both sides. However, the use of microorganism at an industrial
level is deeply rooted into today’s society. The following is a brief over view
of the various microorganisms that have industrial uses and of the roles they
play.
Coryne bacteria are characterized by
their diverse origins. They are found in numerous ecological niches and are
most often used in industrial for the mass production of aminoacids and
nutritional factors in particular, the amino acids produce by coryne bacterium,
glutamicum, include the amino acid glutanic acid. Glutanic acid as used as a
common addition in food production where it is known as monosodium glutamate
(MSG) corynebaterium can also be used in steraind conversion and in the
degradation of hydrocarbons.
Xanthomonas, a type of
proteo-bacteria is known for its ability to canes disease in plant. The
bacterial species which are classified under xanthomonas axibit the ability to
produce the acids exopoly saccharide commonly marketed as xanthan gun used as a
thickening and stabilizing agent in foods and in cosmetic ingredients to
prevent separation.
Another type of micro-organism
utilized by industry includes various species of aspergillums. This genus
species of aspergillums include several hundreds types of molds, aspergillums
has become a key component in industrial microbiology where it is used in the
production of alcoholic beverages and pharmaceutical development. Aspergillums
is most commonly used to produce citric acid, which is used in numerous
products ranging from house hold cleaners, pharmaceuticals, foods cosmetics,
photography and construction aspergillums is also commonly used in large-scale
fermented in the production of alcoholic beverages such as Japanese sake.
DIFFERENT INDUSTRIES AND ROLES OF MICRO
ORGANISMS IN THEM
Baking Industry
Yeast which causes bread to rise is a microbe without
fermentation by yeast, which is a living and natural product, we could not
obtain the equivalent of bread of Viennese pastry. In the process of
fermentation yeast, produces carbon dioxide, alcohol, and other compound which
enable dough to rise and modify it’s physical properties when the fermentation
is correctly achieved depending on the quality of flour among other things, the
baker will obtain the proper external and internal characteristics (grain and
texture) suitable for a determined finished product.
Why bread has holes and grows molds
yeast the most fundamental biological process in bread making is fermentation
initiated and sustained by the life activities of a unicellular plant, a
microscopic yeast cell. Baker’s yeast cerevsiae species and is actually a
member of the mushroom family. It is a biological leavening agent and possesses
the basic attributes of all living things, which are respiration and
reproduction, it’s role in bread making is to convert sugars to carbon dioxide
gas and thus leaven the dough. Yeast fermentation is also involved in the
maturation of the dough and like wine or bear, contributes greatly to the
production of bread taste.
BACTERIA IN BAKING INDUSTRY
Bacteria also contribute either positively or
negatively to the overall quality of the finished loaf in sour dough bread,
bacteria cultures are categorized under the rather poorly defined “wild yeast”
category. This is in reference to ambient yeast and bacterial microorganism
already present in the flour, mater, air, on your hands contacts with the
dough. Bacterial growth, like yeast, is affected by moisture, ph, temperature,
food supply salt, sugar, oxygen supply and light most bacterial grow well in
moist environments with temperatures ranging between 25-400C,
however and like it colder (just over freezing and some like it hot (60-80%)
bacteria thrive at a PH around neutrality (65-80) most chemical will kill
bacteria. Since bacterial will not grow in mediums with large amounts of salt,
salt plays a contributing factor to the leavening of sour dough bread, it is
important to note that not all bacteria is beneficial to bread some cause
infections that have negative effects on the finished product. High hydration
doughs are more susceptible to bacterial infections like ropy bread and
particularly interesting “Bleading Bread”.
MOLD IN
BAKING INDUSTRY
The
presence of mold in baking ingredients, equipment or product is deterious and
undesirable. Molds constitute a principal group of spoilage organisms most of
the ingredients used in baking are subjects to molds infections as well as
finished leaves. There are two types of the most common molds mucor. Bluesih
mold
Rhizopus: black mold.
WINE
INDUSTRY
In the wine making process, yeast cells are kept short
of oxygen, causing sugars. In grape juice to ferment forming alcohol and carbon
dioxide, in making of cheese and yoghurt, bacteria perform a similar job,
turning lactose into lactic acid. Rennet is then added to separate the curds
and whey.
Lactic acid bacteria (LAB) are responsible for many
fermented food such as saver krant, pickles and yogurt. They have also been
isolated from mines at various states of vinification, in wines they are
responsible for malolactic fermentation (MLF) which can be beneficial in some
cases and undesirable in others.
Besides conducting (MLF), these bacteria under certain
conditions can also cause undesirable changes in wine flavor which renders the
wine undrinkable. Many species of LAB do not conduct MLF and their growth in
wine an cause some serious wine spoilage.
FLOUR MILL
INDUSTRY
Microbial and bacterial contamination of wheat flour
has seldom been a concern due to the fact that it has low water activity level,
water activity (AW) refers to the availability of mater in a food or beverage
and represent the amount of water that is available to microorganism pure water
has an AW of 1.00, A water activity level of greater than 0.95 is required to
support the growth of bacteria.
Wheat flour generally has an Aw level of 0.87 or lower
depending on flour moisture and temperature the concern with wheat flour is
that bacteria can be carried or stored and emerge from dormancy when the flour
is further processed when the flour is further processed into a food product in
the milling process prevention and reduction of microbial or bacteria
contamination are good alternatives with elimination options growing in
acceptance, but adding significant cost to production.
VIRUSES IN
FOOD INDUSTRY
Viruses unlike bacteria, cannot
multiply in foods. The main mode of transmission therefore by food handlers and
the use of dirty utensils, which transfer the virus to food where upon it is
ingested by humans.
·
Rotaviruses and
nor walk virus are the major causes of gastroenteritis
·
Viral hepatilits
A ontbraks are mainly caused by asymptomatic carriers which handle food.
PARASITES IN FOOD INDUSTRY
Many
parasites, such as the helminthes, have a complex lifecycle involving more than
one host. The major route of transmission for these parasite to humans is by
the route of food the consumption of undercooked prok or beef, or the
consumption of raw salads washed in contaminated water seems to be the trend.
The most commonly used
microorganisms are yeast, bacteria, moulds, or a combination of these. A goo
example of microorganism usage in food production is the process of
fermentation which result in the production of organic acid, alcohols and esters.
CONCLUSION
Baker’s yeast which is sacchromyces. Cerevisiae is
widely use in many food industries for example in bread industry it is used to
leaven bread dough convert sugars to carbon dioxide gas in wine industry yeast
cells are kept short of oxygen, causing sugars in grape juice to ferment
forming alcohol and carbon dioxide. It is also used to brew beer.
Bacterias also play enough roles again in the food
industries for example in the making of yogurt and cheese bacteria is used to
convert lactose into lactic acid. Lactic acid bacteria are responsible for many
fermented food such as saver krant, prickles.
With this I will say that microorganisms are good
friends to food producers if they are ready to make them friends.
REFERENCES
Bartowsky,
E. J., Costello, P. J. Abrahamsen, C.E. McCarthy, J. M, Chambers, P. J. Herderich, M. J. & Pretorius, I. S. (2009) wine bacteria wine industry
journal 24(2).
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