Chapter 28

noisymaniacalBiotechnology

Feb 20, 2013 (4 years and 8 months ago)

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Chapter 28

Applied and Industrial
Microbiology

Food Microbiology


Food preservation essential for modern civilization


Many methods discovered by accident


Foods prepared centrally and widely distributed


FDA and USDA


Hazard Analysis & Critical Control Point


“Farm to the Fork”


Home canning


Commercial sterilization


Uses
retort



Thermophilic bacteria may be resistant


Thermophilic anaerobic spoilage


low
-
acid foods


Can swells, lowered pH and sour smell



Flat sour spoilage



Can not swollen as no gas is produced



Mesophilic spoilage


under processed or contaminated foods



Lower temps used with acidic foods


Some microbes both heat and acid resistant


Aseptic packaging



Plastics or paper


Hydrogen peroxide, UV light,
electron beams




High pressure



Radiation



completely sterilizes food


Doesn’t change taste or
appearance


gamma rays or electron
accelerators


Electronic pasteurization

Microbes in Food Production


Cheese


Curd (
casein

protein) separated
from liquid
whey


Aided by action of
Lactococcus
and
rennin
enzyme


Ripened or un
-
ripened


Physical and microbial ripening


Classified by degree of hardness


Hard cheeses


Ripened by lactic acid bacteria in interior


The longer the incubation the higher the acidity and
sharper the flavor


Propionibacterium



swiss cheese


Softer cheeses are ripened by aerobic bacterium
and molds on surface


Penicillium



blue cheese


Other fermented dairy products:


Buttermilk, sour cream, yogurt and fermented
milk beverages


Lactococcus lactis
,
Streptococcus
thermophilus

and
Lactobacillus bulgaricus



Non
-
Dairy fermentations


Sauerkraut, coffee, pickles, soy sauce,
chocolate, coffee, olives, meats and fish


Lactococcus, Streptococcus, Lactobacillus
and Aspergillus



Bread fermentations:


Saccharomyces cervisiae



Aerobic conditions favor CO
2
production


Kneading


Lactic acid bacteria produce tart flavor


sourdough and rye breads



Alcoholic fermentations


Yeasts, molds and bacteria
ferment grains, rice or fruits


Saccharomyces cervisiae,
Aspergillus, Leuconostoc




Beer and ale require
malting


Starch converted to glucose



Aspergillus

molds used in
Sake (rice wine)



Wines made from fruits do not
require malting



Malolactic

fermentation with
grapes


Leuconostoc

convert malic
acid into lactic acid



Distilled spirits involve
fermentation of fruits, grains,
or vegetables


Vinegar production


Aerobic bacteria oxidize ethanol
to acetic acid


Different flavors due to different
starting materials


Acetobacter and Gluconobacter



Industrial Microbiology


Biotechnology



rDNA technology


Industrial fermentation

Bioreactors

Primary M
etabolites

Formed with new
cells, during the log
phase or
trophophase

Secondary M
etabolites

Produced during the
stationary phase or
idiophase


May be due to
conversion of primary
metabolites



Industrial Products


Food additives and supplements


Amino acids


Organic acids


Citric acid


Aspergillus


Acetic acid

-

Acetobacter


Vitamins


Pseudomonas, Ashbya
fungi
, Acetobacter



Microbial enzymes


Amylases


Aspergillus


1
st

biological patent


Pectinase


Clostridium



Proteases


Restriction enzymes and polymerases



Pharmaceuticals


Antibiotics


Streptomyces



Steroids


Cortisone; estrogen; progesterone


Hormones


Insulin; human growth hormone


Vaccines


Dyes



Green jeans



Alternative fuels


Renewable resources


Bioconversion


Biomass

Methane, ethanol, hydrogen


Microorganisms themselves as products


Baker’s yeast


Saccharomyces cerevisiae



Insecticide
-

Bacillus thurengenisis


Bt toxin


Frost inhibitor



Pseudomonas syringae

ice
-