Lab exam chapter 8 Flashcards
(37 cards)
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
