This document discusses food microbiology. It covers topics like microbial contamination and spoilage of food, food safety, food testing, significance of microorganisms in food, food spoilage, food contamination, and types of food contamination. The key points are that food microbiology studies microbes that inhabit, infect or contaminate food. Microbes can cause food spoilage or foodborne illness if the food is improperly handled or stored. Microbes are also used to produce fermented foods like cheese, yogurt and bread. Ensuring food safety requires testing for pathogens and spoilage microorganisms.

1. Food Microbiology
Mrs. Praveen garg
VITS College, Satna
 Microbial contamination and Spoilage

2.  Food microbiology is the study of
the microorganisms that inhibit, create,
or contaminate food.
 This includes the study of microorganisms causing
food spoilage.
 Pathogens can cause disease especially if food is
improperly cooked or stored.
 Micro-organisms used to produce fermented
foods such as cheese, yogurt, bread, beer,
and wine.
INTRODUCTION

4.  Food safety is a major step of food microbiology.
 Numerous agents of disease and pathogens are
readily transmitted via food which
includes bacteria and viruses.
 Microbial toxins are also possible contaminants of
food; However, microorganisms and their products
can also be used to combat these pathogenic
microbes.
 Probiotic bacteria, including those that
produce bacteriocins can kill and inhibit pathogens.
FOOD SAFETY

6.  Alternatively, purified bacteriocins such as nisin can
be added directly to food products.
 Bacteriophages, viruses that only infect bacteria can
be used to kill bacterial pathogens.
 Through preparation of food, including
proper cooking, eliminates most bacteria and
viruses.
 However, toxins produced by contaminants may not
be liable to change to non-toxic forms by heating
or cooking the contaminated food due to other safety
conditions.

7.  Fermentation is one of the methods to preserve
food and alter its quality.
 Yeast, especially Saccharomyce scerevisiae, is
used to leaven bread, brew beer and make wine.
 Certain bacteria, including lactic acid bacteria,
are used to make yogurt, cheese, hot
sauce, pickles, fermented sausages and dishes.
 Some cheese varieties also require molds to ripen
and develop their characteristic flavors.
FERMENTATION

9. A microbiologist working in a biosafety laboratory
tests for high risk pathogens in food.

10.  To ensure safety of food products, microbiological
tests such as testing for pathogens and spoilage
organisms are required.
 Polymerase chain reaction(PCR) is a quick and
inexpensive method to detect different kinds of
viruses or bacteria, such as HIV and anthrax based
on their unique DNA pattern.
 The detection of bacterial strain in food products is
very important to everyone in the world, for it helps
prevent the occurrence of food borne illness.
 Therefore, PCR is recognized as a DNA detector in
order to amplify and trace the presence of pathogenic
strands in different processed food.
FOOD TESTING

12. • Alginates can be used as thickening agents.
• It is 'Microbial polysaccharides', commercial
produced by extraction from brown seaweeds such
as Laminaria hyperborea or L. japonica.
• Poly-γ-glutamic acid (γ-PGA) produced by various
strains of Bacillus has potential applications as a
thickener in the food industry.

13. Microorganisms are of great significance to foods for
the following reasons:
 Microorganisms can cause spoilage of foods,
 Microorganisms are used to manufacture a wide
variety of food products,
 Microbial diseases can be transmitted by foods.
SIGNIFICANCE

14. • Food spoilage may be defined as any change that make food
unfit for human consumption.
• These changes caused by various factors, such as
contamination by microorganisms, infestation by insects,
or degradation by endogenous enzymes (those present naturally
in the food).
• In addition, physical and chemical changes or the oxidation of
certain constituents of food, may promote food spoilage.
• Foods obtained from plant or animal sources begin to spoil
soon.
• The chemical reactions catalyzed by the enzymes present in
food, result in the degradation of food quality, such as the
development of off-flavours, the deterioration of texture, and the
loss of nutrients.
• The typical microorganisms that cause food spoilage are
bacteria (e.g., Lactobacillus), yeasts (e.g., Saccharomyces), and
molds (e.g., Rhizopus).
FOOD SPOILAGE

15.  Foods can be considered as a medium for
microbial growth.
 Food gives a chance to grow, microbes will produce
changes in appearance, flavour, odour, and other
qualities of the food.
 The changes vary according to the type of food
degraded.
 Protein-containing foods, particularly meats, are
putrefied by organisms (e.g., Proteus, Pseudomonas,
and Clostridium bacteria) that break down the
long peptide chains of proteins into amino acids and
foul-smelling compounds such as amines, ammonia,
and hydrogen sulfide (H2S).
FOOD CONTAMINATION

16.  Carbohydrates (sugas and starches)
are fermented into acids (e.g., the acetic
acid in vinegar), alcohols, and gases,
especially carbon dioxide.
 This process is responsible for the bursting of
spoiled chocolate cream candies by yeasts.
 Fat-containing foods such as dairy products are
spoiled by microbes that break down lipids
into fatty acids and glycerol.
 Rancid milk, which can be caused
by bacteria, yeast, or mold, is an example of this
process.

17.  Canned foods are also subject to spoilage by
bacteria, yeasts, and molds.
 Bacteria such as Bacillus and Clostridium are of
particular significance in the canning industry
because of the high level of resistance that their
spores possess.
 Prevention of contamination is achieved by the
sanitary handling of raw food products.
 Inhibition of growth by low temperatures
(refrigeration or freezing), dehydration by
evaporation or by high concentrations of salt or
sugar.
 Killing of microbes by the application of high
temperatures and, in some instances, radiation.

18.  When food items are not handled or cooked safely,
the disease-causing organisms such as bacteria,
parasites, and viruses result in food
contamination.
The common reasons for food contamination are:
 Improper storing, handling and preparing food
 Improperly cleaned or sanitized utensils
 Contamination by flies, cockroaches, insects, and
pests

19.  There are a number of reasons that can lead
to food contamination.
 Food contamination falls under four different
categories which are:
• Biological contamination
• Chemical contamination
• Physical contamination
• Cross-contamination
•
TYPE OF CONTAMINATION

20.  Biological contamination is one of the common
causes of food poisoning as well as spoilage.
 Contamination of food items by other living
organisms is known as biological food contamination.
 During biological contamination, the harmful
bacteria spread on foods that you consume. Even a
single bacterium can multiply very quickly when they
find ideal growth conditions.
 Process of multiplying can be quite harmful to
humans.
 The common places where you can find bacteria are:
• Dust, Raw meat, The air, The human body, Pets and
pests, Kitchen clothes.

22.  Physical contamination occur when harmful
objects contaminate the food.
 At times, food items can have both physical
and biological contamination.
 Some of the safety tips that you can follow when
handling food items to prevent food contamination
are:
• Hair-Tie your hair when handling food
• Glass or Metal-Clean away cracked or broken
crockery and utensils to avoid contamination
• Dirt-KENT Vegetable and Fruit Cleaner helps in
removing dirt from fruits and vegetables

24.  Cross-Contamination can lead to a number of
health problems.
 Many of us are not aware of cross-contamination.
 Cross-contamination takes place when pathogens
are transported from any object that you use in the
kitchen.
 Dirty kitchen clothes, unclean utensils, pests, raw
food storage can lead to cross-contamination

26.  Chemical contaminants are one of the serious
sources of food contamination.
 These can also lead to food poisoning.
 Pesticides present in fruits and vegetables are one of
the main sources of contamination.
 In addition, kitchen cleaning agents, food containers
made of non-safe plastic, pest control products also
lead to food contamination.
 However, plain water can’t remove all the
contaminants.
 KENT Vegetable and Fruit Disinfectant can help to
remove chemicals.

28. THANK YOU