1. SUBMITTED TO: DR. RAJANI JOSHI SUBMITTED BY: DEEPIKA JAIN
M.V.Sc (1st yr)
VPH
2. Food spoilage can be defined as “any sensory change (tactile,
visual, olfactory or flavour)” which the consumer considers
to be unacceptable.
Food spoilage is a metabolic process that causes foods to be
undesirable or unacceptable for human consumption due to
changes in sensory characteristics. Spoiled foods may be safe
to eat, i.e. they may not cause illness because there are no
pathogens or a toxin present, but changes in texture, smell,
taste or appearance cause them to be rejected.
3.
4. When food is exposed in air for a long time,
water comes out through the leaves and skin of
fruits and vegetables .
Moisture loss affects both the appearance and
texture of foods.
e.g. – the fruit shrinks in size.
the skin becomes wrinkled.
5.
6. What is “enzyme”?
Enzymes are proteins that speed up chemical
reactions – Enzymes are inactive until the food is
harvested or the animal is slaughtered.
They are sensitive to heat and they remain
inactive at very low temperature e.g. in freezer.
7. When fruits or vegetables are peeled or cut,
the plant tissue releases some enzymes
which in the presence of oxygen from the
air, chemically react with plant compounds
to give brown pigments. This reaction is
known as enzymatic browning.
8. ENZYMATIC REACTION:
The reaction makes the food unappealing and
limits the shelf life of many fruits and vegetables.
Plant compounds
(polyphenol)
Brown pigment
(melanin)
Polyphenol
oxidase
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10. Stop the action of enzyme:
Enzymes are proteins and they are destroyed by acids and
salts.
e.g. – brush or dip the banana slices in fruit
juice which is acidic e.g. lemon juice,
orange juice etc.
– soak the slices in salt water.
11.
12. Limit the access of oxygen:
Oxygen is required for browning reaction:
Immerse the cuts in cold water .
Cover the fruits immediately after peeling with
a plastic wrap.
13. Chemical changes begin automatically after
fruits and vegetables are harvested, or animals
are killed (slaughtered).
Oxygen in air, sunlight and high temperature
can cause certain foods to undergo undesirable
chemical changes.
14. Chemicals affect fats and pigments in the food which
causes changes in colour and flavour of foods:
E.g. unpleasant smell and taste of cooking oil after use
at high temperature.
The red pigment in meat undergoes chemical changes
and turns brown when it is exposed to oxygen.
The meat looks unappealing but it may not be unsafe
for human consumption.
15.
16. Micro-organisms are tiny living things which can
only be seen under a microscope
The main micro-organisms are bacteria, moulds and
yeasts
They can be found in air, water, on most of the foods
and our hands, etc.
Micro-organisms grow rapidly in warm and moist
conditions with food.
17.
18. Food contaminated with bacteria is often
undetected because the food usually looks,
tastes and smells normal.
Harmful bacteria which can cause food
poisoning is known as pathogenic bacteria.
19. Bacteria is responsible for the spoilage of food. When bacteria
breaks down the food, acids and other waste products are
created in the process.
While the bacteria itself may or may not be harmful, the
waste products may be unpleasant to taste or may even be
harmful to one's health.
There are two types of pathogenic bacteria that target
different categories of food. The first type is
called Clostridium perfingens and targets foods such as meat
and poultry, and Bacillus cereus, which targets milk and
cream.
20. Several other bacteria are also responsible for spoilage of
various types of food.
These includes Salmonella, Listeria, Staphylococcus,
Aeromonas, Enterobacter, Shigella, Proteus, Yersinia,
Vibrio, Serratia, Pseudomonas, Campylobacter etc.
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27. Molds are filamentous fungi that grow in the form
of a tangled mass that spreads rapidly and may
cover several inches of area in 2 to 3 days.
The total of the mass or any large portion of it is
referred to as mycelium.
Mycelium is composed of branches or filaments
referred to as hyphae.
28. Various molds are responsible for
food spoilage.
These includes Aspergillus,
Cladosporium, Fusarium, Geotrichum,
Mucor, Penicillium, Rhizopus,
Trichothecium etc.
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31. Aflatoxins are toxins produced by moulds.
They are commonly found in crops e.g. peanuts, maize,
cereals etc.
Aflatoxins can cause liver damage and cancer in humans.
Conditions that favour the growth of the aflatoxins-
producing moulds:
High humidity
High temperature
Poor handling and storage of crops after harvest .
32. Yeast is also a type of fungus that grows
vegetatively via single cells that either bud or
divide by way of fission, allowing for yeast to
multiply in liquid environments favoring the
dissemination of single celled microorganisms.
Yeast forms mainly in liquid environments and
anaerobic conditions,
33. Yeast causes spoilage of wide variety of foods
due to Candida, Cryptococcus, Rhodotorula,
Saccharomyces, Trichosporon etc.
Yeast can be responsible for the decomposition of
food with a high sugar content. The same effect is
useful in the production of various types of food
and beverages, such as bread, yoghurt, cider,
alcoholic beverages.
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35. A number of methods of prevention can be used that can either
totally prevent, delay, or otherwise reduce food spoilage.
A food rotation system uses the first in first out method
(FIFO), which ensures that the first item purchased is the first
item consumed.
One of the age old techniques for food preservation, to avoid
mold and fungus growth, is the process of drying out the food
or dehydrating it.
36. Other than drying, other methods include salting, curing, canning,
refrigeration, freezing, preservatives and irradiation.
Refrigeration can increase the shelf life of certain foods and
beverages, though with most items, it does not indefinitely expand
it.
Freezing can preserve food even longer, though even freezing has
limitations.
Canning of food can preserve food for a particularly long period
of time, whether done at home or commercially.
Lactic acid fermentation also preserves food and prevents
spoilage.
37. Food like meat, poultry, milk and cream should be kept
out of the Danger Zone (between 40°F to 140°F).
Anything between that range is considered dangerous
and can cause pathogenic toxins to be emitted, resulting
in severe illness in the consumer.
Another way to keep your food from spoiling is by
following a four step system: Clean, Separate, Cook,
Chill. This will reduce any risks.
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42. India is the second major producer of fruits and vegetables and
ranks next to Brazil and China respectively, in the world.
It contributes 10 percent of world fruit production and 14 per
cent of world vegetable production.
Fruits and vegetables are more prone to spoilage than cereals
due to their nature and composition, and this spoilage occurs
at the time of harvesting, handling transportation, storage,
marketing and processing resulting in waste.
43. According to India Agricultural Research Data Book 2004, the losses
in fruits and vegetables are to the tune of 30 per cent. Taking
estimated production of fruits and vegetables in India at 150 million
tones, the total waste generated comes to 50 million tones per annum.
Like any other food, fruits and vegetables are also prone to microbial
spoilage caused by fungi, bacteria, yeast and moulds.
The most common pathogens causing rots in vegetables and fruits are
fungi such as Alternaria, Botrytis, Diplodia, Monilinia, Phomopsis,
Rhizopus, Pencillium, Fusarium, etc.
Among bacteria Ervinia, Pseudomonas, etc. can cause extensive
damage.
44. Proper handling, packaging, transportation and storage
reduce the post-harvest losses of fruit and vegetables.
For every one percent reduction in loss will save 5 million
tons of fruit and vegetable per year. Processing and
preservation technology helps.
There are about 4000 small and large scale processing
units in the country which process only about 2.5% of the
total fruit and vegetable as against 40-85% in developed
countries.
