Food microbiology Flashcards
HTST
high t, short time
Why canning?
increase shelf life at room temperature
How to can acidic food?
T: 100 C
How to can non acidic food?
autoclave: 121 C
What is 12D process?
10^12 spores of Clostridium botulinum killed
How to take out water to inhibit growth?
- sun dry
- hot air drying
- freeze-drying (lyophilization) result in little lost of quality but is really expensive
Irradiation
Radappertization
kill ALL microorganism
Irradiation
Radicidation
kill SPECIFIC microorganisms
Irradiation
Radurization
reduce overall contamination
Purpose of nitrites
prevent growth of clostridium botulinum
present in celery extract (natural)
Purpose of sulfites
-wine industry
=inhibits wild yeast
What produces Nisin
lactococcus lactis
What is a primary metabolite
a metabolite produced during exponential growth
What is a secondary metabolite
produced when microorganisms are in the stationary phase
-competition
Is a fermentor like a chemostat?
YES
What does a fermentor control? (4)
- temperature
- nutrients
- pH
- dissolved oxygen
Gmo to produce 2 things (that we learned)
Insulin
rennet (baby cows)
Staphylococus areus : endotoxin or exotoxin
exotoxin
food poisoning
E. Coli : endotoxin or exotoxin
endotoxin
infection
Salmonellosis : food poisoning or infection
infection
endotoxin
C botulinum in adults : infection of food poisoning
food poisoning
C botulinum in infants : infection of food poisoning
infection
What type of yeast to produce a good beer?
Saccharomyces cerevisiae
In fermented products, what are the types of microorganisms the most often used?
lactic acid bacteria
yeasts
Define Lactic acid bacteria (4 characteristics)
- GRAM +
- AEROTOLERANT ANAEROBES
- Rods or cocci
- homofermentative or heterofermentative
Homofermentative and heterofermentative both produce
Lactic acid
Homofermentative (some food)
pickles,
sauerkraut = choucroutte
Heterofermentative (some food)
Sausages (Salami)
fermented milk products
Name 2 yogurt cultures
Streptococcus thermophilus
Lactobacillus bulgaris
Curdling of cheese : what does precipitate the cheese to make a curd?
Lactic acid bacteria
Ripening of cheese : what adds flavor?
lactic acid bacteria and other organisms
What cleaves casein?
Lactic acid bacteria or rennin
Principal steps to make cheese (5)
1 add starter culture 2 add rennin or lactic acid bacteria 3 whey is drained off 4 heat it, not eat it 5 add salt (optionnal)
Cheese ripening
Cheddar : what bacteria do we add
lactic acid bacteria
Cheese ripening
Swiss cheese : what bacteria do we add for holes
how much time required for ripenning?
Propionibacteria
3-12 months or longer
Cheese ripening
Blue and roquefort : what bacteria do we add
how much time required for ripenning?
Penicillium roquefort
the molds grows in the holes and produces spores (blue)
and takes (3-6 months)
Cheese ripening
Brie <3 and Camembert : what bacterias do we add
How long is the ripening process?
Penicillium
Brevibacterium (on surface)
1-5 months
Wine
What do we add to kill the yeast?
MEtabisulfite
Wine
Max percentage of alcohol
(without adding alcohol in the wine)
12-14 %
Dry wine… is all the sugar fermented?
yes
Sec wine… is all the sugar fermented?
no
Vinegar (process of fermentation or not)
no
vinegar
ethanol= acetaldehyde=
acetic acid
Glutenberg contains gluten ?
no ;)
How do we call the mash when it is filtered?
WORT
Lager beer : what strain
Saccharomyces carlsbergensis
Ale beer : what strain
Saccharomyces cerevisiae
Page beer : what strain
LOL
name the Gin from mtl?
Ungava
What grain
vodka
wheat rye or potato
What grain
Gin
grains or starchy product + juniper oil and other flavor ingredients
What sugar
Rum
sugar cane ( molasses)
ALL microorganisms need…
Water,
water is life
drink water
aw<0,8 only specialized organism can grow :
Xerophiles (conditions? )
dry environment
low osmolarity
aw<0,8 only specialized organism can grow :
Osmophiles (conditions?)
high osmolarity
high sugar
aw<0,8 only specialized organism can grow :
Halophiles (condition?)
high salinity
In what type of food can we find Norovirus if not well stored or handled?
Shellfish
Hoes does the NASA treat their food ?
Irradiation
GRAS
antispoilage
Generally recognized as safe :,)
Nitrite
sulfites
nisin
What microorganisms are naturally found on cabbage (2)
1- Leuconostoc mesenteroides
2- Lactobacillus plantarum
What microorganism is used to ferment sausage, salami, bologna and pickles
Lactobacillus plantarum
What temperature is the yogurt incubated
42
what does the lactic acid bacteria do to the protein
it precipitate the protein : curd
how do you call the whey
supernatant
What does rennin and lactic acid bacteria do to the casein
they both cleave casein which result in the formation of the curd
What is the purpose of ripening (3)
texture
consistency
flavor
Oka cheese, what is special about it (2)
during ripening, it is frequently washed, and Geotrichum grows
What can we add to the wine (2)
Sugar and organic acid
Acetic acid bacteria (aerobe or anaerobe)
aerobe
so Vinegar is not a product of fermentation
What microorganism we use for vinegar
Acetobacter
True of False
Acetic acid bacteria oxidize ethanol to acetic acid- strict aerobes, this is not a fermentation process
true
Brewing
What are the key factors (5)
1- water 2- malt 3- hops 4- yeast 5- condition of fermentation (t, time)
WMHYF
What my health you face
Do yeast digest starch?
no
How do you call the process of grains germinating?
Malting
How do you call the process of which the grains are dried and crushed?
Malt
How do you call the process of soaking the malt in warm water (65c) for 1-2 hr?
mashing
What degrades the stach?
amylase
What is the Hops used for?
flavor
bitterness
prevents lactic acid bacteria to grow in the final product
What is polishing?
filtration, carbonation, pasteurization
Is hops in both beer and distilled alcoholic beverages?
only in beer
Is a food spoiled necessarily harmful
no, think about the cheese that becomes blue,
you can cut that part…
What pathogens can grow at 4.5 c
Yersina enterocolitica,
Listeria monocytogenes,
Clostridium botulinum
What is food infection?
organisms are ingested with the food and multiply in the host.
Botulism food : poisoning or infection
food poisoning
ingestion of the neurotoxin produced by C. botulimum
Salmonella enterica : food poisoning or infection
food infection
grows in you
E Coli
44.5 c kills it or not
no, it inhibits its growth
but if you cook it at high temperature, you will kill the it.
e. Coli food poisoning or infection
infection
AB-type exotoxin
3 methods to pasteurize milk
LTLT
HTST
UHT
