Lecture 15 - microbes and food

Question 1

Which bacteria added to milk in cheese production

Answer 1

lactobacilli
Reduces pH

Question 2

What does renin contain

Answer 2

chymosin which is a protease enzyme

Question 3

what does rennet do

Answer 3

removes charged peptide side chains from casein
To make para kappa casein
Which allows particles to coagulate ie curds

Question 4

What fungus used to carry recombinant chymosin

Answer 4

aspergillus niger

Question 5

Example of surface ripening

Answer 5

penicillium camembert used in camembert cheese
Releases proteases and lipases to make flavour
Only on crust

Question 6

Example of invasive ripening

Answer 6

penicillium roqueforti in roquefort cheese
Injected so it grows thrkught the cheese

Question 7

what fungus used in ales

Answer 7

saccharomyces cerevisia

Question 8

what fungus used in lagers

Answer 8

saccharomyces carlsbergensis

Question 9

what 2 things give ales and lager their flavour

Answer 9

ester = fruity, mosly ales
fusel alchols = stronger flavour, also precursor to ester (beers and lager)

Question 10

origin of citric acid and what is used now

Answer 10

used to be lemons
now aspergillus niger is used

Question 11

what process is A.niger produces citric acid

Answer 11

TCA/krebs cycle

Question 12

what conditions have to be met for citric acid production

Answer 12

low manganese and iron conditions

Question 13

what increases viscosity in gut of poultry making it harder for them to absorb nutrients

Answer 13

arabinoglucans

Question 14

how is arabinoglucan removed

Answer 14

beta glucanase given with feed to poultry
means higher glucan cereal fed to poultry = fat chickens

Question 15

what is phosphate stored as in plants, that cant be degraded by pigs

Answer 15

phytate

Question 16

why is phytate not being absorbed a problem in pig rearing

Answer 16

cuz to give pigs enough phosphate they treat their feeds with phospahte
which is bad for environemnt = algal blooming

Question 17

what is given to pigs to help them degrade phytate

Answer 17

phytase derived from microbes

Question 18

most common causes of food related deaths bateria

Answer 18

campylobacter - the one in chickens
salmonella (most common worldwidw)
listeria
e.coli

Question 19

some causes of food borne disease outbreaks

Answer 19

mass production and processing
mass transport
change in human pop - ageing etc.
new straisn and antibiotic resistance

Question 20

what are high risk groups for food borne diseases

Answer 20

any groups with compromised immune systems

Question 21

how can pre prepped salads be a source of listeria

Answer 21

not cooked, and shredding process releases sugars that the bact feeds on
and bact grows at fridge temp

Question 22

what is a solution to listerial contamination

Answer 22

chloronating food

Question 23

why is listeria a problem is it is rare

Answer 23

high mortality rate

Question 24

what are the more serious symptoms of lsiteria

Answer 24

at first its normal food poisioning
but can become systemic
= meningitis, septicemia
bad for pregnant wolmen

Question 25

what are mycotoxins

Answer 25

fungal metabolites produced after fungus grows on food

Question 26

what is the most toxic version of mycotoxin

Answer 26

aflatoxins
(produced by Aspergillus fungi)

Question 27

aflatoxin short term and long term symptoms

Answer 27

short term = normal food poisioning symp
long term = cancer, liver/kidney failure and some brain damage

Question 28

what is ergot posioning caused by

Answer 28

claviceps purpurea
a black fungus grows on cereals

Question 29

what disease is associated with ergot poisoning

Answer 29

st anthony’s fire

Question 30

symptoms of st anthoys fire

Answer 30

sever burning joint pain
hallucinations
gangrene