1. MECHANISM OF CONTAMINATION OF
FRUITS & VEGETABLES

2. INTRODUCTION
• The mechanism of contamination of fruit and
vegetables begins from the field (farm), pre-harvest,
during harvest and post-harvest, storage and
processing, till consumption.
• Fruits and vegetables provide an abundant &
inexpensive source of energy, body-building nutrients,
vitamins and minerals.
• Most of our food consists of agricultural products,
which are usually seasonal and spoil quickly.
• Humans are mostly stored fruits and vegetables in
refrigerator to prevent spoilage.
• The use of preservative is predominantly used to
postponed the rotting process, optimizing storage
condition or applying modern techniques.

3. Fruits and Vegetables
Fruits and Vegetables: Fruits and vegetables are
considered edible parts of plants (e.g. seed bearing
structures, flowers, buds, leaves, stems, shoots and
roots), either cultivated or harvested wild, in their raw
state or in a minimally processed form.

5. Post-harvest
Harvest
Pre-harvest

6. Pre-harvest
• Cultivar Type
• Soil Condition
• Climatic Conditions and Irrigation
• Farming system (Conventional or Organic)
• Fertilisation
• Pest Control Method
• Pruning

7. • A cultivar is a plant or grouping of
plants selected for desirable
characteristics that can be maintained
by propagation
• Cultivars are plant types that have
been bred by humans for a particular
trait, such as taste, smell, color.
• Many cultivars must be propagated
vegetatively through cuttings, grafting,
and even tissue culture. Propagation
by seed usually produces something
different than the parent plant

8. Soil Condition
Soil condition can be
defined as the capacity of a
soil to function, within land
use and ecosystem
boundaries, to sustain
biological productivity,
maintain environmental
health, and promote plant,
animal, and human health.
Soil is a natural body
comprised of solids
(minerals and organic
matter), liquid, and gases
that occurs on the land
surface, occupies space,
and have the ability to
support rooted plants in a
natural state

9. Farming system (Conventional or Organic)
Subsistence
farming.
Irrigation
Farming.
Shifting
Farming.
Plantation
Farming
Characteristics of Conventional Farming. 1 Use of
chemical fertilisers. 2 Use of chemical pesticides. 3
Use of chemical weed killers. 4 Use of genetically
modified organisms which can deliver consistent
crops. 5 Production of only one or two crops in the
same field per growing season or year.
In Organic none of this characteristic

10. Pest Control Method
Biological
Method..
Chemical
Method..
Mechanical
Method.
Poisoned Bait
Method.
Trap
Cropping. ...

11. Fertilisation
The process of
fusion of the
nucleus of the
male cell ( the
pollen grains )
with the nucleus
of the female cell
( the ovum ) to
form the zygote

12. Farming system
Subsistence
farming.
Irrigation
Farming.
Shifting
Farming.
Plantation
Farming

13. Pruning
• When you prune correctly, you encourage healthy
growth and flowering (in the case of flowering
plants),
• Infected pruning knife or the cut on the plant could
be entry point for microbes or contaminant.
• Examples of instrument used are secateurs, loppers,
long reach pruners, tree pruning systems and saws

14. Harvest
• Maturity stage
• Methods of harvesting
• Tools for harvesting and assembling
• Time of harvesting

15. Post-harvest
• Precooling
• Sorting and grading
• Packing, packing materials, and palletisation
Storage
• Type of storage
• Temperature during storage and transportation
• Temperature and Relative Humidity (RH)
Transportation
• Road condition
• Pattern of loading and unloading
• Exposure to packed and unpacked boxes to sunlight

16. • Contact with spoiling fruits and vegetables may
transfer micro organisms & increasing wastages .
• Mostly spoilage occurring due to microbial action
such as bacteria, yeast, & moulds.
• Bacteria & Yeast cannot be seen with the naked
eyes.
• Bacterial soft rot: caused by Erwinia caratovora
Pseudomonas, Clostridium, Bacillus sps may
also isolated from these rots
Post-harvest contd

17. Microbiological Hazards (Example Micro-organisms)
• Listeria monocytogenes
• Escherichia coli VTEC
• Campylobacter jejuni
• Clostridium botulinum
• Clostridium perfringens
• Staphylococcus aureus
• Salmonella choleraesuis
• Salmonella parathyphi A,B and C
• Shigella dysenteriae

18. Chemical hazards
Pest control agent
Sanitising agent
Water additive
From Packing
Materials
Printing code inks
Adhesives
Lubricant
Raw materials
Heavy metal
Pesticide/insecticide
residues
Toxin
In the Process
Refrigerant (strong
smell &toxin)
Lubricant (grease &
oil)

19. Physical Hazards
Insect
infestation
Particles
• Glass
• Metal
• Plastic
• Wood
• Paper

20. SPOILAGE OF FRUITS AND VEGETABLES:
• Contact with spoiling fruits and vegetables
may transfer micro organisms & increasing
wastages .
• Mostly spoilage occurring due to microbial
action such as bacteria, yeast, & moulds..
• Bacterial soft rot: caused by Erwinia
caratovora Pseudomonas, Clostridium,
Bacillus sps may also isolated from these rots

21. Infectiousness –
ability to initiate and
maintain an infection
in a host
Invasiveness – the
power to progress
further into the host
from initial infection
Pathogenicity - the ability
to injure a host once an
infection is established

22. • Use of Heat- Inactivate their enzymes &
reduce the multiplication & load of Mo’s.
• Use of low temperature- For example Apple,
Potatoes can be preserved for a limited time.
• Chilling- Using cold water, ice or mechanical
refrigerator or by vacuum cooling.
• -Cold water spray for precooling after
harvesting.
• -Each fruits has its own Optimum temperature
& relative Humidity for chilling storage.

23. • During storage in frozen condition, it will
decrease the number of organisms.
• -In fruits for freezing, undesirable changes may
takes place such as darkening, deterioration in
flavor & spoilage of micro organisms especially
molds.
• - For example yeast (Saccharomyces,
Cryptococcus sps.), Molds (Aspergillus, Mucor,
Rhizopus sps.) have been Reported organism in
Frozen fruits.

24. • The number of micro organisms in dried fruits
& vegetables is comparatively low and that
spores of bacteria and molds are likely to be
the most numerous.
• - This result in additional loss of water
(dehydrate), but more number a porous
network of capillaries is formed in the
product.
• The increased porosity simplifies further
drying and imparts good reconstituting ability

25. • Chemicals have been applied to fruits chiefly as a
dip or spray or impregnated in wrappers for Fruits
• -Among substances that have been applied to the
outer surfaces of fruits & vegetables are waxes,
hypochlorite’s, biphenyl, and alkaline sodium o-
phenyl phenate.
• -Sodium chloride is the only added chemical
preservatives in common use.
• -Zinc carbonate eliminate most mold on lettuce,
beets, Biphenyl vapors will control Fusarium sps.