Lab exam chapter 8 Flashcards
What is microbially fermented foods
those transformed by naturally occurring or added microbes into a product that has an increased shelf life
What are examples of raw material for fermented foods
meat
fish
fruit
vegetables
grains
dairy
Is microbial contaminants in food pathogenic
no many are harmless to the food and the person that consumes the food
WHat are significant microbial contaminants of food that can cause foodborne illness
listeria monocytogenes
staphylococcus aureus
salmonella enterica
What are fermented food products the result of
metabolic activity by bacteria and or fungi and the usually involve microbes that grow by fermentation
What can be added to yogurt cheese sausage wine
specific starter cultures
What do sauerkraut and chocolate depend on
wild fermentation accomplished by indigenous organisms that are present in the starting material
What are the main microbes involved in food fermentation
lactic acid bacter
acetic acid bacter, yeast, and molds
LAB are gram __________ and shaped
positive; rods and cocci
What are homolactic fermenters
produce LA as the primary end product of glucose
What are heterolactic fermenters
produce equal amounts of LA, ethanol, and CO2
How do you identify heterolactic fermenters
hoot loops test do determine CO2 production
What oxygen relationship is usualy for LA bacteria
aerotolerant anaerobes
T/F heme containing compounds (oxidase) and H2O2 breakdown (catalase) are absent in LA bacteria
true
LA bacteria tend to be ________ organism and need media that has many growth factors
fastidious
LA is resistant to
azide
What are lactic acid bacteria that ferment lactose used in making
fermented milk products
Strains of ___________- and _______________ are often used in sausage production
lactoabacillus
pediococcus
Many vegetable fermentations proceed with the growth of bacteria naturally occuring on the harvested plants; LAB such as ____________- and _____________ are commonly ued
leuconostoc
lactobacillus
In the examples we look at LAB is
able to inhibit spoilage
Some fermentaitons add sodium chloride as a ___________ agent
selective; won’t inhibit the desired fermenting bacteria but does prevent the growth of undesirable microbes
What LAB strains mostly cause pathogens
leuconostoc produce slime from sucrose
What is the reason some LAB cause greening on meat
excessive hydrogen peroxide
What are the two examples of ethonal fermenting microbes
saccharomyces
zymomonas mobilis
What is saccharomyces species used for
breakmaking and to produce alcoholic beverages and kombucha
What type of respirators are saccharomyces
facultative anaerobes
What is Z. mobilis used in
production of alcoholic beverages
What gram is acetic acid bacteria and shape
gram negative rod shaped
What are AAB abundant in
fruit
Where do AAB usually grow
aerobic conditions
What do AAB convert
ethanol to acetic acid
What are AAB that convert ethanol to acetic acid used in the produciton of
vinegar
chocolate
kombucha
What is an enrichment
A treatment or medium used to favor the growth of desired organisms
What does a sucessful enrichement do
increase the population of desired organisms over undesired organisms–easier to isolate
LAB is difficult to grow on
all purpose media
We expect LAB to grow on what agar but not the other agar
APT; YTG
before a hot loop test and ATP broth innoculation what must the resutls be
catalase neg
gram positive
able to ferment glucose
