Microflora of Food

 MICROFLORA OF FOOD

1) Meat

Natural/Typical Microflora	Pseudomonas, Acinetobacter, Moraxella, Micrococcus, Flavobacterium
Spoilage Organisms	Pseudomonas, Shewanella, Lactic Acid Bacteria, Clostridium spp.
Sources of Contamination	Slaughterhouse environment, intestinal contents, knives, workers, tables, water, air
Spoilage Characteristics	Sliminess, sour smell, discoloration, putrid odor, rancidity
Preservation Methods	Refrigeration, freezing, vacuum packing, drying, curing, irradiation, canning

2) Fish and Seafood

Natural/Typical Microflora	Pseudomonas, Acinetobacter, Moraxella, Bacillus, Flavobacterium, Vibrio
Spoilage Organisms	Pseudomonas fluorescens, Proteus, Serratia, yeasts, molds
Sources of Contamination	Water, slime, gills, gut, fishing boats, nets, ice, boxes, handlers
Spoilage Characteristics	Fishy odor (trimethylamine), sour smell, green or brown discoloration, softening
Preservation Methods	Chilling, freezing, canning, salting, smoking, drying, irradiation

3) Eggs

Natural/Typical Microflora (Shell)	Micrococcus, Staphylococcus, Bacillus, yeast/mold spores
Spoilage Organisms	Green rot – Pseudomonas fluorescens; Black rot – Proteus; Pink rot – Serratia; Penicillium & Cladosporium
Sources of Contamination	Nests, fecal material, cages, washing water, handlers
Spoilage Characteristics	Colour change (green, black, pink), gas, foul odor, mold "whiskers"
Preservation Methods	Washing and disinfection, oil coating, refrigeration, freezing, drying, pasteurization

4) Fruits

Natural/Typical Microflora	Yeasts (e.g., Saccharomyces, Candida), molds (Penicillium, Mucor, Rhizopus)
Spoilage Organisms	Same as above, especially molds in storage
Sources of Contamination	Soil, wind, rain, harvesting tools, baskets, transport, washing water
Spoilage Characteristics	Soft rots, fermentation, off-flavors, discoloration, mold growth
Preservation Methods	Refrigeration, canning, drying, waxing, chemical dips, irradiation, controlled atmosphere storage

5) Vegetables

Natural/Typical Microflora	Pseudomonas, Erwinia, Bacillus, Clostridium, molds (Botrytis, Cladosporium, Alternaria)
Spoilage Organisms	Soft rot bacteria and molds
Sources of Contamination	Soil, harvesting tools, boxes, water, damaged tissues, handling
Spoilage Characteristics	Soft rot, sliminess, foul odor, discoloration
Preservation Methods	Refrigeration, drying, pickling, fermentation, irradiation, canning

6) Fruit & Vegetable Juices

Microflora	Yeasts, coliforms (from spoiled/rotten fruits), lactobacilli
Spoilage Organisms	Saccharomyces, Candida, Pichia
Sources of Contamination	Use of bruised/damaged fruits, dirty equipment, insufficient heating, packaging contamination
Spoilage Characteristics	Gas formation, turbidity, sour taste, swollen containers
Preservation Methods	Pasteurization, freezing, aseptic packaging, preservatives (sorbates, benzoates)

7) Flour/Cereal Products

Microflora	Bacillus spores, molds, Micrococcus
Spoilage Organisms	Bacillus spp. (ropey bread), molds
Sources of Contamination	Soil, milling machines, storage silos, insects, moisture
Spoilage Characteristics	Ropey texture, musty odor, moldy patches, discoloration
Preservation Methods	Dry storage, fumigation, airtight packing, refrigeration for mixes, low moisture

8) Canned Foods

Microflora After Canning	Heat-resistant spores: Bacillus spp., Clostridium spp.
Spoilage Types	-        Flat-sour: Thermophilic Bacillus (no gas) -        Gas spoilage: Clostridium botulinum, C. sporogenes
Sources of Contamination	Surviving spores due to improper heating, contamination from dirty equipment
Spoilage Characteristics	Sour smell, gas, swollen cans, cloudy liquid, may produce toxins
Preservation Methods	Proper thermal processing, retorting, low pH, chemical preservatives, aseptic packaging