Effect of gaseous atmosphere on food microbes.pptx food preservation microbes activity on food FOOD MICROBIOLOGY

1. Effect of gaseous
atmosphere on food
microbes.
Submitted by
Inderjeet Singh L-
2021-A-09-BTFT

2. Growth and survival of microorganisms in
food ~
Presence and concentration of gases in the
environment
Exposure of foods to gases in the storage
environment (gaseous environment) affects
growth and survival of microorganisms in foods.
Since exposure of food to oxygen favors growth of
aerobic microorganisms, gaseous environments
need to be modified to ensure reduced microbial
activity and resultant spoilage. This approach is
commonly employed in the preservation of fruits
and vegetables.

3. Gases used to control
microorganisms in foods
Carbon dioxide, ozone and nitrogen are the most
important gases used to control microorganisms
in food. Several ready to eat foods are packed in
the presence of these gases to reduce microbial
activity and extend shelf life of packed foods.
Such foods are referred to as Modified
Atmosphere Package (MAP) foods.
Carbon dioxide is the single most important
atmospheric gas used to control microorganisms
in foods and is used in varying concentrations
depending on the type of food. Carbon dioxide in
elevated pressure is also used in carbonated
water and soft drinks. Molds and Gram negative
microorganisms are more sensitive to CO2 than
Gram positive bacteria. Lactobacilli are resistant
to CO2.Yeasts show considerable resistance and
tolerate high CO2 levels but can cause spoilage
of carbonated beverages (Ex. Brettanomyces sp.)
Carbon dioxide mainly acts as a
bacteriostatic
agent. But some microorganisms are killed by
prolonged exposure.Mechanism of inhibition
of
CO2 is due to the formation of carbonic acid
which lowers pH. Lowered pH affects physical
properties of the plasma membrane of
microorganisms and affects solute transport,
inhibits key enzymes, and reacts with amino
groups of proteins causing changes in their
property and activity.
Ozone (O3) also has antimicrobial properties
and
extends shelf life of certain fruits and
vegetables
foods. O3 concentration of 0.15-5 ppm is
known to
double the shelf life by inhibiting spoilage
bacteria and yeast.
Carbon dioxide is effective for extending the
shelf-life of perishable foods by retarding
bacterial growth.

4. Effect of atmosphere
packaging on the
microbial
spoilage and shelf-
life of fresh-cut
honeydew melon
This study evaluated
the potential of
modified atmospheres
(MAs) combining high
oxygen (O₂) and high
carbon dioxide (CO₂)
levels to extend the
shelf-life of fresh-cut
honeydew melon.

5. MAP uses liquid nitrogen or a gas mixture
in modified atmosphere packaging to
retain the original taste, texture and
appearance of the product being
packaged. MAP gas mixtures usually
consist of nitrogen (N2), carbon dioxide
(CO2) and can contain other gases such
as nitrous oxide, argon or hydrogen.

6. ★ Discoveries
Scientists Just Created a Bacteria That Eats
CO2 to Reduce Greenhouse Gases Researchers
engineered a strain of E. coli bacteria that can
consume carbon dioxide and turn it into energy.
The synthetic life-form could someday help
combat climate change.
By Alex Orlando Nov 27, 2019 10:30 PM
Researchers hope to tap
synthetic life-forms to convert
atmospheric carbon dioxide, or
CO2, into food, fuel and organic
chemicals that humans can use.
But many previous attempts, like
a 2016 effort to synthesize sugar
from CO2 in bacteria, have seen
limited success.

7. Submitted to Dr. Jaspreet Kaur Sian
➔ Offline
From Book
Moderen Food
microbiology
4rth edition
➔ Online
Sites
Google
,ecoursesonline
iasri.res.in ,
Discovermagazine
Biotechnologynotes,
pubmed.ncbi.nlm.nih.
gov,
References