Lecture 15 - microbes and food Flashcards
Which bacteria added to milk in cheese production
lactobacilli
Reduces pH
What does renin contain
chymosin which is a protease enzyme
what does rennet do
removes charged peptide side chains from casein
To make para kappa casein
Which allows particles to coagulate ie curds
What fungus used to carry recombinant chymosin
aspergillus niger
Example of surface ripening
penicillium camembert used in camembert cheese
Releases proteases and lipases to make flavour
Only on crust
Example of invasive ripening
penicillium roqueforti in roquefort cheese
Injected so it grows thrkught the cheese
what fungus used in ales
saccharomyces cerevisia
what fungus used in lagers
saccharomyces carlsbergensis
what 2 things give ales and lager their flavour
ester = fruity, mosly ales
fusel alchols = stronger flavour, also precursor to ester (beers and lager)
origin of citric acid and what is used now
used to be lemons
now aspergillus niger is used
what process is A.niger produces citric acid
TCA/krebs cycle
what conditions have to be met for citric acid production
low manganese and iron conditions
what increases viscosity in gut of poultry making it harder for them to absorb nutrients
arabinoglucans
how is arabinoglucan removed
beta glucanase given with feed to poultry
means higher glucan cereal fed to poultry = fat chickens
what is phosphate stored as in plants, that cant be degraded by pigs
phytate
why is phytate not being absorbed a problem in pig rearing
cuz to give pigs enough phosphate they treat their feeds with phospahte
which is bad for environemnt = algal blooming
what is given to pigs to help them degrade phytate
phytase derived from microbes
most common causes of food related deaths bateria
campylobacter - the one in chickens
salmonella (most common worldwidw)
listeria
e.coli
some causes of food borne disease outbreaks
mass production and processing
mass transport
change in human pop - ageing etc.
new straisn and antibiotic resistance
what are high risk groups for food borne diseases
any groups with compromised immune systems
how can pre prepped salads be a source of listeria
not cooked, and shredding process releases sugars that the bact feeds on
and bact grows at fridge temp
what is a solution to listerial contamination
chloronating food
why is listeria a problem is it is rare
high mortality rate
what are the more serious symptoms of lsiteria
at first its normal food poisioning
but can become systemic
= meningitis, septicemia
bad for pregnant wolmen
what are mycotoxins
fungal metabolites produced after fungus grows on food
what is the most toxic version of mycotoxin
aflatoxins
(produced by Aspergillus fungi)
aflatoxin short term and long term symptoms
short term = normal food poisioning symp
long term = cancer, liver/kidney failure and some brain damage
what is ergot posioning caused by
claviceps purpurea
a black fungus grows on cereals
what disease is associated with ergot poisoning
st anthony’s fire
symptoms of st anthoys fire
sever burning joint pain
hallucinations
gangrene
