_ These slides describes about the food spoilage in the food and their causative organisms too _ And how to prevent the food spoilage

1. R. Nisha
Department of Microbiology
Sacred Heart College (Autonomous)
Tirupattur.

2. WHAT IS THE DIFFERENCE?

3. SPOILAGE OF FRUITS AND
VEGETABLES
• The organism responsible for taints are acid tolerant
bacteria:
– Lactobacillus spp.
• Deterioration can be caused by action of animals, birds,
bruising, wounding, cutting, freezing, dessication or
other mishandling and growth of microorganisms;
environmental conditions, contact with spoiled foods.
• Microbial spoilage maybe due to:
– Plant pathogens acting on stems, leaves, flowers or roots
– Saprophytic organisms

4. • Types of spoilages:
– Baterial soft rot
• Caused by Erwinia carotovora, ferment pectins
• Pseudomonas marginalis, Bacillus and
Clostridium cause water soaked appearance, a
soft, mushy consistency and bad odour.
– Anthracnose
• Caused by Collectotrichum lindemuthianum.
• Spotting of leaves and fruits
– Black mold rot
• Caused by Aspergillus niger
• Dark brown to black masses of spores of the
mold termed as smut

5. • Rhizopus soft rot
– Caused by species of Rhizopus
– Soft and mushy rot
– Cottony growth of mold forms black spots of
sporangia covering the foods.
• Alternaria rot
– Caused by Alternaria tenuis
– Greenish-brown to brown black spots
• Fungal spoilage results in water soaked mushy
areas, brown or cream coloured areas. Rots of
juicy fruits result in leakage.

6. SPOILAGE OF CEREALS
• Moisture content above 12 to 13 percent may cause
spoilage of cereals
• Little moisture cause mold growth and high moisture
may cause growth of yeasts and bacteria.
• Microbial content, physical damage and temperature
are also some factors.
• Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium are
some common molds; produce mycotoxins.
• Acetobacter spp, lactics and Coliforms, Micrococci and
Bacillus are some species causing spoilage.

7. • Cause flour dough to develop an odour of
acetic acid and esters
• Ropiness of bread is common in home baked
bread
– Caused by Bacillus subtilis, B. licheniformis and
other species
– Due to the capsulation of Bacillus ropiness occurs.
– First odour is evident, then discolouration and
finally softening of the crumb with stickiness and
stringiness.
• Red bread is caused by the pigmented growth
of Serratia marcescens. Molds such as
Neurospora sitophila and Geotrichum
aurantiacum can also cause red colouration.

8. SPOILAGE OF MILK
• An excellent medium
• Souring
– caused by Streptococcus lactis, Enterococci,
Lactobacilli, Micrococci
• Gas production
– caused by Coliform, Clostridium, Yeasts, Bacillus
• Proteolysis
– cause bitter taste, caused by Bacillus, Micrococcus,
Proteus, Pseudomonas, Flavobacterium, Serratia.
• Changes in colour and tastes

9. SPOILAGE OF MEAT
• Raw meat is subject to spoilage by its own
enzymes and microbial action.
• Excessive autolysis can cause souring
• Factors involving spoilage include
– The greater gut load of animal
– The physiological condition of the animal during
slaughter as like fever, excited or fatigued.
– Rapid cooling

10. SPOILAGE OF FISH
• Spoiled by autolysis, oxidation or bacterial
activity.
• Under aerobic conditions
– Surface slime
• Caused by Pseudomonas, Moraxella, Alcaligens,
Lactobacillus, Streptococcus,
Leuconostoc,Bacillus,Micrococci.
– Change in colour of meat pigments
• Red colour, green,brown or grey

11. –Change in fats
• Rancidity
• Lipolysis
• Oxidation of fats
–Phosphorescence
• Photobactererium spp growing on meat
―Surface colours due to pigmentation
• Red spot caused by Serratia marcescens
• Chromobacterium gives a greenish blue colour
• Pseudomonas gives a bluish colour

12. • Micrococcus or Flavobacterium gives a yellowish
colour.
• Pencillium may cause greenish colour.
• Cladosporium may cause black colour
—Off odours and Off tastes
• Taints, Souring, stale flavour can be caused as a
result of bacterial and fungal growth.

13. SPOILAGE OF EGGS
• Cracks, leaks, stained or dirty spots on exterior
and blood clots, bloodiness, translucent spots
in the interior are all signs of spoilage
• Pseudomonas, Acinetobacter, Alcaligens,
certain coliform bacteria. Proteus spp,
Aeromonas, Serratia, Sporotrichum all cause
rots in eggs

14. SPOILAGE CAN LEAD TO…
• Food Poisoning
• When someone gets sick from eating food or
drink that has gone bad or is contaminated.
• There are two kinds of food poisoning:
poisoning by toxic agent or by communicable
agent.

15. HOW CAN WE PREVENT?
• FOOD PRESERVATION
• What is food preservation?
• Food preservation is the process of treating and
handling food ,with an aim to stop or slow down
its spoilage while maintaining its nutritional
value, texture, and flavour.
• Food preservation methods either kill microbes
or prevent their growth.

16. Some methods are:
1. Boiling
2. Dehydration
3. Refrigeration & freezing
4. Canning
5. Using chemical preservatives
6. Using Salt, sugar, oil, or vinegar
7. Pasteurization

17. “Better pay the chef than the doctor!”