Chapter 28 - Nashua School District

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6 Δεκ 2012 (πριν από 4 χρόνια και 10 μήνες)

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Applied and Industrial Microbiology


Foods & Disease


Because we distribute
food that was prepared
in central facilities the
chance of widespread
disease is more likely.


The USDA and FDA
inspect these facilities to
set standards for these
facilities to prevent
contamination.


The earliest forms of
food preservation were:
adding salt/sugar,
fermentation, and
drying.

The Role of Microorganisms in
Food Production (MFP)

CHEESE!

1.
The milk protein
casein curdles because
of the action by lactic
acid bacteria or the
enzyme
rennin/
chymosin
.

-
Cheese is the curd
separated from the
liquid portion of milk,
called whey

MFP: Cheese Continued

2.
Hard cheeses
are
produced by lactic acid
bacteria growing on
the interior of the curd

-
growth of microbes in
cheese is called
ripening

3.
Semisoft cheeses
are
ripened by bacteria
growing on the surface;


MFP: Other Dairy Products

1.
Old
-
fashioned
buttermilk was
produced by lactic acid
bacteria growing
during the butter
-
making process

-
commercial buttermilk is
made by letting lactic
acid bacteria grow in
skim milk for 12 hours

Sour cream,
yogurt, kefir,
and kumiss
are produced
by lactobacilli,
streptococci,
or yeasts
growing in
low
-
fat milk.

MFP: Nondairy Fermentations

1.
Sugars in bread dough
are fermented by yeast
to ethanol and CO2;
the CO2 causes the
bread to rise

2.
Sauerkraut, pickles,
olives, and soy sauce
are products of
microbial fermentation

MFP: Alcoholic Beverages and
Vinegar

1.
Carbohydrates obtained
from grains, potatoes, or
molasses are fermented
by yeasts to produce
ethanol in the production
of beer, ale, sake, and
distilled spirits.

2.
Sugars in fruits such as
grapes are fermented by
yeasts to produce wines



Industrial Fermentation:


The large
-
scale cultivation of microbes or
other single cells to produce a
commercially valuable substance.


Also used in biotechnology to obtain
useful products from genetically
engineered plant and animal cells.


Fermentation Technology


Bioreactors:


Vessels for industrial fermentation and
is designed with close attention to
aeration, pH control, and temperature
control.


Sometimes very large and can hold up to
500,000 liters.

Fermentation Tech: Industrial Fermentation

Bioreactors


Primary metabolite:


A product of an industrial cell population
produced during the time of rapid
logarithmic growth.


Secondary Metabolite:


A product of an industrial cell population
produced after the microorganism has
largely completed it’s period of rapid
growth and is in stationary phase of growth
cycle.

Fermentation Tech: Metabolite


Strain improvement is also an ongoing
activity in industrial microbiology.


A well
-
known example is that of the mold
used for penicillin.


The original culture of
Penicillium

did
not produce penicillin in large enough
quantities for commercial use.

Fermentation Tech: Strain Improvement

Industrial Food Canning


Industrially canned goods undergo what is called
commercial
sterilization
, by steam under pressure in a large retort which works
like an autoclave.


Commercial sterilization is intended to destroy
C. Botulinum,

because
if that endospore is destroyed, then any other spoilage or pathogenic
bacteria will also be destroyed.


The 12D treatment is used to decrease the amount of
C. Botulinum

by
12 logarithmic cycles (10
12
). This treatment is considered safe because if
there were 1,000,000,000,000 endospores in a can, there would be one
survivor after the 12D treatment.


Thermophilic anaerobic spoilage

is a fairly common cause of
spoilage in low
-
acid canned foods. The can usually swells from gas, and
the contents have a lowered pH and a sour odor.


When thermophilic spoilage occurs and the can isn’t swollen by gas
production, the spoilage is called
flat sour spoilage
.





Chapter 28

Aseptic Packaging & The Future of
Industrial Microbiology


Packages are usually made of materials that are tolerant to
conventional heat treatment (laminated paper or plastic)


The packaging materials came into continuous rolls that
are fed into a machine that sterilizes the material with hot
hydrogen peroxide solution
-

sometimes aided by
ultraviolet light.


Metal containers can be sterilized with superheated steam.


While still in the sterile environment, the material is
formed into packages, which are filled with liquid foods
that have been sterilized by heat.

Chapter 28

Amino Acids


lysine

and
methionine

are amino acids that cannot be
synthesized by animals.


In nature, microbes only produce the amount of amino
acids needed. No excess will be made due to feedback
inhibition.


Commercial amino acid production occurs in a lab where
the microbe is manipulated to create more amino acids to
be used.


Citric Acid


Citric Acids are in fruits such as lemons and oranges.


Citric Acid gives tartness to foods, serves as a pH
adjuster and antioxidant. In dairy, it serves as an
emulsifier.


Most commercially produced citric acid is produced by
the mold,
Aspergillus niger.

Enzymes


The production of
amylases

was the first
biotechnology patent given by the U.S.


Enzymes are used in manufacturing foods, medicines
and other goods that microbes produce.

Vitamins


Vitamins are tablets that are used as food
supplements.


Most microbe species produce the majority of vitamins
people take.

Pharmaceuticals


Most antibiotics were originally produced by microbes.
Today, we can also synthetically produce antibiotics.


Vaccines are made by means of industrial
microbiology.


Steroids can also be synthesized by microorganisms.

Copper Extraction


The metabolic activity of
Thiobacillus

ferrooxidans
is
used to recover uranium and copper ores


An ore is a metal
-
bearing mineral or rock


Thiobacillus

gets its energy from the oxidation of a
reduced form of iron. This energy is used to recover
copper ores.

Microbes as Industrial Products


Some microbes are purposefully produced in mass
amounts to be used in production.


For example S. cerevisiae or (Baker’s yeast) is produced
in large fermentation tanks.


After, the yeast is packaged into yeast cakes to be sold
for baking at home.


Organic waste, called biomass, can be
converted by microorganisms into
alternative fuels, a process called bio
conversion.


Examples of fuels produced by microbial
fermentation are methane and ethanol.