b) List four important factors that are involved in meat spoilage.
ANS- Basic Types of Food Spoilage
Appearance: when a food "looks bad," what is this referring to?
Microbial growth
mycelia or colonies visible on surface
development of cloudiness in liquids
Changes in food color due to heme or chlorophyll breakdown
colony pigments, growth of mycelia, etc.
Textural changes (feel)
Slime formation
due primarily to surface accumulation of microbial cells
also be a manifestation of tissue degradation
Tissue softening due to enzymatic degradation (e.g. soft rot in veggies)
Changes in taste and odor
Development of:
1. nitrogenous compounds (ammonia, amines, etc.)
2. sulfides
3. organic acids
The numbers and types of MO in a food are largely determined by:
Environment from which the food was obtained.
Microbiological quality of the food in its raw or unprocessed state (intrinsic factors).
Handling and processing sanitation.
Effectiveness of packaging, handling and storage conditions in restricting microbial growth (extrinsic factors).
Fresh Meats:
Chemical composition:
-75% water
-18% protein
-3% fat, 1% ash, traces of CHO, vitamins, etc.
1. Whole Meats:
The microflora of fresh meat is composed primarily of:
1. Gram negative aerobic rods such as Pseudomonas, Acinetobacter and Moraxella.
2. Bacillus and clostridia (e.g. C. perfringens) are also common on all types of meat.
Although subsurface portions of meat are generally sterile, some parts such as lymph nodes may be heavily contaminated.
Mechanical disruption of the tissue during processing can distribute microorganisms from the meat surface throughout the product.
Fresh meats are among the most perishable foods.
Storage temperature is the single most important control factor for meat spoilage.
Handout - Sources of Contamination
Several genera of molds grow on the surface of meat and can cause spoilage, but cannot grow on meat stored below 5oC.
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