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25 Cards in this Set
- Front
- Back
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What is food spoilage?
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The loss of quality (sensorial) or safety aspects of the food.
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What are the broad types of food spoilage? - give examples
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-physical: moisture loss
-Chemical: lipid oxidation -Biological: enzymatic (browning) microbial pests (insects) |
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What are types of microbial food spoilages?
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Can either be microbial growth or microbial enzymes.
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What types of microbes spoil food?
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Bacteria, yeasts & molds. Not protozoa usually.
Bacterial growth rate>>>yeats>>mold |
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What are the three most common food spoilage bacteria?
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Bacillus (thermoduric/thermophile)
Lactobacillus (aciduric) Pseudomonas (psychrotrophic/aerobe) |
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Which is the one that glows in the dark?
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Pseudomonas fluorescens
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What levels of microorganism are needed for "detection" of spoilage (sensory)?
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Cells are detected when >10^6.
Spoilage compounds H2S, amines, h202 detected at <10^6 |
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What are the products of aerobic respiration? Anaerobic?
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Aerobic: CO2 mostly/ glucose-->metabolites-(o2)->co2
Anaerobic: Fermentation products glucose-->metabolites--->acids, ethanol |
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When proteins are degraded, what are the bi-products:
1. aerobically? 2. anaerobically? |
1. CO2
2. Cadaverine, putriscine, etc. - a lot of nasty, foul shit |
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What is the main end product in dairy causing bad flavors?
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diacetyl
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What organisms spoils fresh meat?
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No dominent group. Many types (inc. pseudomonas and lactobacillus); molds and yeasts too.
Low carbs/some NPN/High H20 |
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How to control fresh meat spoilage?
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Control T, O2. Sanitary plant practices.
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Why does atmospheric control delay microbrial spoilage of meat if anaerobes can still grow?
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Anaerobes typically have slower growth rates than aerobes.
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Why does meat turn brown/gray?
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Oxidation of myoglobin
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How does meat spoil?
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Bacterial: off-odors, color change, slime (coalescence of colonies), souring (ferm. bi-products)
Fungal: spots/whiskers |
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How is meat spoilage typicaly detected?
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Physical methods - pH, WHC, others.
Can also do chemically, but takes too long. Or Bacteriological methods, but same limitation. |
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What is curing?
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Treating meat with a mix of salts/ nitrites or nitrates
NO3->no2->no which reacts with myoglobin & keeps pink |
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Cured (processed) meat spoilage microbe most implicated?
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LAB: lactic acid bacteria. Gram + regular rods. Lactobacillus.
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What modes of failure for processed meats?
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Sliminess
Souring LAB!!! Greening |
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What is greening of meat caused by?
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H202 or H2S reaction with myoglobin
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How to prevent spoilage in processed meats?
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Additives (antimicrobials)
HPP Microbial quality of ingredients |
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What group of microbe most important w/food spoilage of fish? Salted fish?
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STRICT aerobes. - pseudomonas, for example.
In salted fish, yeasts & molds. |
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How to prevent fish spoilage?
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Control o2!!!
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What happens as fish degrades?
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Off odors
loss of texture (proteolysis) Sliminess |
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In fish, what leads to off smells/flavors?
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degradation of NPN to TMA
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