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What conditions are most favourable for microbial food production? -…
What
conditions
are
most favourable
for
microbial food production
?
cultures
bacteria
yeast
mould
microbial food
bread
beer
wine
vinegar
yoghurt
cheese
fermented fish
fermented meat
fermented vegetables
variables to be tested
independent
pH
temperature
moisture
dependent
bacterial growth
favourable conditions
intrinsic factors
steady supply of water
foods vary dramatically in terms of water availability
fresh meats and milk have high water content that supports
microbial growth
breads, nuts and dried foods have low water availability
pH neutral (low acid)
important in determining which organisms can survive and thrive on specific foods
many microorganisms are inhibited by acid conditions (Exception include lactic acid bacteria)
lactic acid bacteria used in fermentation process of food production
fungi able to survive at relatively low pH
most acid foods spoil from fungal contamination as opposed to
bacteria
pH can determine bacteria’s ability to produce toxin
protein-rich (nutrient availability)
nutrients present in food determine organisms that can grow in foods
biological barriers
rinds, shells and other outer coverings help protect foods from microbial invasion
microorganisms will eventually breakdown coverings and cause spoilage
antimicrobial chemicals
some foods contain natural antimicrobial chemicals that inhibit growth of organisms responsible for spoilage
osmotic pressure
extrinsic factors
storage temperature
below freezing water availability is significantly decreased
water crystallizes and is unavailable halting microbial growth
at low temperature (above freezing) enzymatic action is very slow or non-existent
results in inability of microbe to grow
atmosphere
presence or absence of oxygen affects type of microbial population
obligate aerobes cannot grow under anaerobic conditions
obligate anaerobes will grow in anaerobic conditions
including certain food-borne pathogens