Introduction

1. College of Health Sciences
Dep. of Medical Laboratories
Food Microbiology Theory
3rd stage
Lecture 1
Dr.: Shameeran S. Ismael
BVM & S, M.Sc Medical Microbiology(Parasitology),
PhD Molecular Parasitology

2. Microbiology
• Microbiology is the study of all living
organisms that are too small to be visible with
the naked eye. This includes bacteria, archaea,
viruses, fungi, protozoa and algae

3. Food Microbiology
• Food microbiology covers areas of food and
fermentation microbiology.
• It focuses on the study of microbial ecology
related to foods like spoilage, fermentation,
preservation, investigation of food borne
outbreaks and national and international Food
Legislation.

4. Why study Food Microbiology?
• Provide clean, Safe, healthful food to
consumer
• Prevent Food Spoilage
• Prevent Food-borne disease
• Food preservation and production

5. Microorganisms and Food
• The foods that we eat are rarely if ever sterile.
• They carry microbial associations whose
composition depends upon which organisms
gain access and how they grow, survive and
interact in the food over time.
• The micro-organisms present will originate
from the natural micro-flora of the raw
material

6. • And those organisms introduced in the course
of harvesting, processing, storage and
distribution .
• The numerical balance between the various
types will be determined by the properties of
the food, its storage environment, properties
of the organisms themselves and the effects
of processing.

7. Micro-organisms manifest their presence
in one of several ways:
1.They can cause spoilage.
2.They can cause food borne illness.
3. They can transform a food’s properties in a
beneficial way – food fermentation

8. History of Microbiology in Food:
• The Chinese , Greeks and Egyptians were used
salted fish in their diet as early as 3000 BC
• Fermented sausages were prepared and
consumed by the ancient Babylonians and the
people of ancient China as far back as 1500
BC
• The Romans excelled in the preservation of
meats other than beef by around 1000 BC and
are known to have used snow

9. • in 1658 Kircher was the first person suggest the role
of microorganisms in spoiling foods examined
decaying bodies, meat, milk, and other substances
and saw what he referred to as "worms" invisible to
the naked eye.
• In 1765, Spallanzani showed that beef broth that had
been boiled for an hour and sealed remained sterile
and did not spoil.
• The event that led to the discovery of canning had its
beginnings in 1795, when the French government
offered a prize of 12,000 francs for the discovery of a
practical method of food preservation

10. • In 1809, a Parisian confectioner, succeeded in
preserving meats in glass bottles that had been kept in
boiling water for varying periods of time.
• Leeuwenhoek in the Netherlands had examined
bacteria through a microscope and described them in
1683.
• In 1837, Pasteur showed that the souring of milk was
caused by microorganisms. In about 1860 he used
heat for the first time to destroy undesirable
organisms in wine and beer (pasteurization)

11. Food spoilage
• Food spoilage is defined as damage or injury
to food rendering in unsuitable for human
consumption.
• Food must be considered spoiled if it is
contaminated with pathogenic microorganisms
or various poisonous agents, such as
pesticides, heavy metals etc.

12. Causes of food spoilage
There are five main ways in which food can be
contaminated are:
1.Growth and activity of microorganisms, Bacteria,
yeasts and molds are microorganisms that cause food
spoilage. They produce various enzymes that
decompose the various constituents of food.
2 Enzyme activity: Action of enzymes found inherently
in plant or animal tissues start the decomposition of
various food components after death of plant or
animal.
3.Chemical reactions: These are reactions that are not
catalysed by enzymes.,e.g. oxidation of fat

13. 4.Vermin. Vermin includes ants, rats, cocroaches,
mice, birds, larval stages of some insects.
Vermin are important due to:
i. Aesthetic aspect of their presence
ii. Possible transmission of pathogenic agents
iii. Consumption of food
5.Physical changes. These include those changes
caused by freezing, burning, drying,
pressure, etc

14. Sources of microorganisms in food
• The primary sources of microorganisms in
food include:
1. Soil and water
2. Plant and plant products
3. Food utensils
4. Intestinal tract of man and animals
5. Food handlers
6. Animal hides and skins
7. Air and dust

15. Thanks for attention,,,
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