1.
Name- Kratika Mehta
and
Harsh Kumar Singh
B.Tech Food technology
3 semester

2.
MICROORGANISMS IN FOOD
 Microbes are single-cell organisms so tiny that
millions can fit into the eye of a needle. They are
the oldest form of life on earth.
 The first realization that microorganisms were
involved in food production processes was in 1837,
when scientists discovered the role of yeast in an
alcoholic fermentation.

3.
WHAT KINDS OF MICROBES ARE FOUND IN FOOD?
 Bacteria
 Fungi (Yeasts and Moulds)
 Protozoans, Algae, Helminths to a
lesser extent
 (Helminths = worms)
 Protozoans and Helminths are
considered “accidental”.

4.
ROLE OF MICROORGANISMS IN PREPARATION OF CERTAIN FOODS -
 Microorganisms are involved in producing many foods
and beverages.
 Fermentation produces characteristic flavors, aromas,
and consistencies of various foods.
 Microbial metabolism has other functions
I. Acts as a preservative
II. Destroys many pathogenic microbes and toxins
III. Can add nutritional value in form of vitamins or other
nutrients
 Microbes are used in food production.

5.
PRODUCT MICROORGANISMS SUBSTRATE
Bread Saccharomyces cerevisiae, yeast, lactic acid Wheat, rye,
Soy Sauce Aspergillus oryzae Soybeans and wheat
or
A. soyae Lactobacillus
Cheese Lactic acid bacteria Milk
Yogurt S. thermophilus, Lb. bulgaricus Milk, milk solids
Sauerkraut Lactic acid bacteria Cabbage

6.
CHEESE-MAKING PROCESS
 Milk is treated with lactic acid, bacteria and an enzyme
called rennin that partially hydrolysis the protein and
causes it to coagulate into “curds”. The liquid portion of
the milk at this time is called “whey”.
 The whey is separated from the curds, and the curds
are aged (“ripened”)
 Different microbes in the early and late stages of
processing give rise to cheeses with different
characteristics

7.
YOGURT PRODUCTION
Milk is fermented by a mixture of Streptococcus
salivarius ssp thermophilus and lactobacillus
bulgaricus. Often these two are co-cultured with other
lactic acid bacteria for taste or health effects
(probiotics). These include L. acidophilus, L. casei and
Bifidobacterium species.
 Acid produced from the fermentation causes the
protein in the milk (casein) to coagulate into a semisolid
curd .
 If you want strawberries or peaches, you must add
them after the yogurt is made.

8.
BREAD PRODUCTION
o Involves growth of saccharomyces
cerevisiae (baker’s yeast) under aerobic
conditions .
o Maximizes CO2 production, which leavens
bread .
o Other microbes used to make special
breads (e.g. sourdough bread) .
o Can be spoiled by Bacillus species that
produce ropiness

9.
THE WINE MAKING PROCESS
 Produced from the fermentation of fruit juice, usually
from grapes. The grapes are crushed to form a
“must”.
 For white wines, white grapes are usually used, and
the skins are removed from the must (“pressing”)
before fermentation.
 For red wines, red or black grapes are used, and the
skin is allowed to remain during fermentation .
 For rosé wines, red grapes are used and the juice is
allowed to remain in contact with the skins just long
enough for a rose or pink colour to develop

10.
WINE
 It must undergoes primary fermentation
• Malolactic fermentation by bacteria in the must
converts malic acid into lactic acid .
 Secondary fermentation and aging
• Takes 3-6 months
• The vessel is kept airtight to prevent oxidation
• Proteins are broken down, and particles settle
 Blending and bottling

11.
THE BEER-BREWING PROCESS
Produced by the fermentation of malted grain
• A series of temperature changes (“mash rests”)
activates different enzymes that, in turn, change the
mash to produce desirable characteristics as well as
fermentable sugars
• In the fermentation tank yeast is added (“pitched”)
• After fermentation for 1-3 weeks the “green beer” is
transferred to conditioning tanks where the yeast &
other particulates are allowed to settle, and the beer
is carbonated.

12.
Probiotics
 Probiotics Is a concentrated
supplement of beneficial live
cells of bacteria (friendly
bacteria) culture taken orally
intended to improve our health
by promoting our body’s natural
immunity and improving
digestion system.

13.
How Do They Work?
Some of the ways they may keep you healthy:
1. When you lose "good" bacteria in your body, for
example after you take antibiotics, probiotics can
help replace them.
2. They can help balance your "good" and "bad"
bacteria to keep your body working the way it
should.

14.
Types of Probiotics
Lactobacillus. This may be the most common probiotic. It's the one
you'll find in yogurt and other fermented foods. Different strains can
help with diarrhea and may help people who can't digest lactose, the
sugar in milk.
Bifidobacterium. You can find it in some dairy products. It may help
ease the symptoms of irritable bowel syndrome (IBS) and some
other conditions.
Saccharomyces boulardii is a yeast found in probiotics. It appears
to help fight diarrhea and other digestive problems.

15.
Are there any risks relatedto probiotics?
Probiotics are generally considered safe. However, there are some risks
linked to the supplements. These risks are increased if you have a medical
condition that weakens your immune system, have recently had surgery or
have other serious medical conditions.
Unlikely, but possible, risks can include:
 Developing an infection.
 Developing a resistance to antibiotics.
 Developing harmful byproducts from the probiotic supplement.