12 - Microbial Spoilage and Public Health Concerns Part 1 Flashcards
can spoiled food still be safe?
yes
how do meat, poultry and seafood differ?
their original microbiotas, handling, and storage requirements
what’s the bacteria population like in muscle tissue of healthy live animals?
absent, undetectable, or present in very low numbers
how is contamination categorized?
- natural
- external
describe natural contamination
originating from the animal (GI tract, skin, feathers)
describe external contamination
originating from processing environment
the first event in meat contamination is:
attachment of bacterial cells to meat surface
what bacteria is particularly good at attaching to meat?
Psuedomonas
why are biofilms problematic?
they are PERSISTANT despite extensive cleaning efforts and can be 10 to 100 fold more resistant to sanitizers
how much meat and fish are lost due to microbial spoilage
- quarter of meat-
- 30% of fish
describe interaction between Pseudomonas, Shewanella, and Listeria
- Pseudomonas inhibits Shewanella by using the same substrates faster
- Pseudomonas promotes Listeria by hydrolysing proteins
define spoilage
consumers rejecting a food based on undesirable sensory characteristics
proteolytic spoilage leads to what kind of odors
putrid
non-proteolytic spoilage results in what kind of odors
sour
microbial spoilage leads to….
- off flavors
- off odors
- off textures
- discoloration
- slime
what is the energy source of spoilage bacteria?
glucose
what is the predominant spoilage organism when oxygen is present?
Pseudomonas
what is the next primary energy source after glucose? and then after that?
lactate; amino acids
why are crustaceans kept alive until cooking?
they have endogenous enzymes that cause rapid postmortem muscle breakdown independent of microbial proteases
how is spoilage evaluated?
- sensory, but it’s subjective
- microbial analysis
what attributes does an ideal spoilage indicator have? (4)
- be absent or present in very low levels in fresh tissue
- be produced by spoilage microflora
- increase with storage time
- correlate well with sensory analysis
what is the main concern of food spoilage with regard to common food-processing treatments?
that AMR bacteria may have higher resistance to these treatments
what is traceability?
ability to maintain credible custody of the identification of animals and their products from production to retail
where does traceability do well and where does it get muddled?
good: from a single animal
muddled: compound products (like ground beef)
what are the dominating spoilage microorganisms in red meat at cold temps?
Psedomonas
how does a stressed animal affect spoilage?
- decreases glucose in tissue
- leads to faster degradation of amino acids
what are the dominant microorganisms that spoil ground meat?
still Pseudomonas, but LAB can dominate the interior given anaerobic conditions
what spoils processed meats?
lower-water-activity tolerating bacteria:
- lactobacilli
- micrococci
how do processed meats spoil?
develop slime, souring, or geening
what microorganism is slime production associated with?
yeasts, Lactobacillus, Enterococcus, Streptococcus, Lueconostoc
what causes spoilage of dry-cured meats?
yeasts or molds that tolerate extremely low water content
what spoilage microorganism predominates poultry during refrigeration?
Pseudomonas spp. yeasts can also be involved.
what are the steps of processing poultry?
- stunning/killing/bleeding
- Scalding
- picking
- evisceration
- chilling
what methods are used for chilling of poultry?
- wet (gains weight)
- dry (loses weight)
which has a higher bacterial load: aquacultured or wild fish?
aquacultured
what foodborne pathogens are associated with seafood?
Salmonella, C. Botulinum, Aeromonas, S. aureus, L. monocytogenes, Vibrio cholerae, Vibrio parahaemolyticus, and vibrio vulnificus
list some biogenic diamines
- histamine
- cadaverine
- putrescine
how are biogenic amines produced?
decarboxylation of specific free amino acids by decarboxylase
consuming biogenic amines can cause what condition?
Scombroid food poisoning
what amino acid leads to the production of histamine by decarboxylase?
Histidine
what can happen in cold-smoked fish products?
putrescine and cadaverine will react with nitrites to produce carcinogens
what are the symptoms of Scombroid food poisoning?
almost identical to food allergy
problem microorganisms associated with shrimp?
- Vibrios in raising waters
- coliforms
- Salmonella
refrigerated: - Pseudomonas
- Aeromonas
problem microorganisms associated with shellfish?
- vibrios in environments
- oysters concentrate stuff
- mussels also concentrate stuff
