1. D R . Z A N W A R S . R .
D E P T O F F I M ,
M G M C F T , G A N D H E L I .
Microbiology of fruits &
vegetables
2. Contamination
During harvesting and containers unless these have
been adequately sanitized.
Mechanical damage during transportation
Soaking, washing, handling
Sweating of products during handling
Wooden surfaces
Hot water blanching - add thermophilic bacteria
Inclusion of decayed
Added ingredients - add thermophilic bacteria
3. Preservation
Vegetables
1. Asepsis
2. Removal of micro
organisms
3. Use of heat
4. Use of Low temperatures
5. Chilling
6. Hydrocooling
7. Freezing
8. Drying
9. Use of preservatives
10. Added preservative
11. Preservation by irradiation
Fruits
1. Asepsis
2. Removal of micro
organisms
3. Use of heat
4. Use of Low temperatures
5. Chilling
6. CA Storage
7. Freezing
8. Drying
9. Use of preservatives
4. Spoilage
Deterioration of raw vegetables and fruits due to
Physical factors
Action of their own enzymes
Microbial action
Mechanical damage
Action of animals, birds, insects.
Wounding
Bursting
Freezing
Dessication
Other mishandling
5. Microbial spoilage of fruit & vegetable
1. Bacterial soft rot
Caused by Erwinia caratovora, these are fermenters
of pectins.
Pseudomonas, Clostridium, Bacillus sps have also
been isolated from these rots.
It results in a water soaked appearance, a soft mushy
consistency and often a bad odor.
6. 2. Gray mold rot
Caused by Botrytis.
It is favored by high humidity and a warm
temperature
7. 3. Rhizopus soft rot
It is caused by sps of Rhizopus Ex: Rhizopus
stolonifer.
This rot is often soft and mushy.
The cottony growth of the mold with small, black
dots of sporangia often covers masses of the foods.
8. 4. Anthrachose
Usually caused by Collectotrichum lindemuthianum,
Collectotrichum coccodes, defect is spotting of
leaves and fruits or seed pods.
9. 5. Alternaria Rot
Caused by Alternaria tenuis.
Areas become greenish brown early in the growth of
the mold and later turn to brown or black spots.
10. 6. Blue mold rot
Caused by Penicillium digitatum.
Bluish green color spores are produced.
11. 7. Downey mildew- Caused by Phytopthora bremia
8. Watery soft rot- Caused chiefly by Sclerotinia
sclerotiorum. Found in mostly vegetables
12. 9. Stem end rots- Caused by Diplodia, Alternaria,
Phomopsis, Fusarium.
10. Black mold rot-
Caused by Aspergillus niger.
Dark brown to black masses of
spores of the mold termed “Smut”.
13. 11. Black rot: Caused by Alternaria, Ceratostomella,
Physalospora.
12. Pink mold rot: Caused by pink spored
Trichothecium roseum.
14. 13. Fusarium rots: Caused by Fusarium sps.
14. Green mold rot: Caused by Cladosporium,
Trichoderma.
15. 15. Brown rot: Caused chiefly by Sclerotinia
(Monilinia fructicola) sps.
16. Sliminess or souring: Caused by Saprophytic
bacteria in piled, wet, heating vegetables.
17. Spoilage of fruit and vegetable juices
Molds can grow on the surface of acidic fruit juices if
juices are exposed to air.
The lactic acid fermentation of sugars, mostly by
heterofermentative lactic acid bacteria such as
Lactobacillus pastorianus, Lactobacillus brevis and
Leuconostoc mesenteroides.
Acetic acid fermentation- by lactic acid bacteria. E.x.
Lactobacillus psatorianus.
Slime production- by Leuconostoc mesenteroides,
Lactobacillus brevis, and Lactobacillus plantarum in
apple juice and by L. plantarum and Streptocooci in
grape juice.
