Food Microbiology exam questions
and answers graded A+
Pure culture advantages (wine making) - ANS✅✅-more consistent and satisfactory
-better flavor obtained from natural mixed cultures
-Saccharomyces cerevisiae commonly used
wild yeast disadvantages (wine making) - ANS✅✅-limited fermentation
-could be harmful to quality once activated in fermentation
Wine aging after bottling - ANS✅✅continues for several months depending on the type of grape
and style of wine
Steps of wine finishing - ANS✅✅1. racking
2. fining and filtering
3. preservatives
4. bottle
5. aging
Racking - ANS✅✅separation of wine from lees (sediment)
fining and filtering - ANS✅✅clarify and sterilize
preservatives - ANS✅✅sterilize and retain color
10^11-12 cells/ml - ANS✅✅density of frozen concentrate starter culture for milk fermentations
Phosphate's role in phage-inhibitory media - ANS✅✅chelates calcium required for phage
absorption
5 main genera that metabolize lactic acid - ANS✅✅Lactococcus, Leuconostoc, Pediococcus,
Streptococcus, and Lactobacillus
, Lactobacillus - ANS✅✅starter culture in dairy, pickles, beer, probiotic (high temp)
Lactococcus - ANS✅✅starter culture in dairy fermentations
Streptococcus thermophilus - ANS✅✅starter culture in dairy fermentation
Leuconostoc - ANS✅✅found in plants, vegetables, silage, milk, dairy, raw and processed meats,
sauerkraut, kimchi
pediococcus - ANS✅✅starter culture mainly in sauerkraut
metabolize glucose - ANS✅✅the purpose of the Leloir pathway is to
Key enzymes in Leloir pathway - ANS✅✅1. galactokinase (GALK)
2. galactose-1P uridylytransferase (GALT)
3. UDP-gal 4'- epimerase (GALE)
Galactokinase (GALK) - ANS✅✅galactose --> Gal-1P
Galactose-1P uridylytransferase (GALT) - ANS✅✅Gal-1P --> UDPGal
UDP-gal 4'- epimerase (GALE) - ANS✅✅1. UDPGalactose --> UDPGlucose
2. UDP- GalNAc --> UDPGlcNAc
Lactobacillus only - ANS✅✅genus that carries out Leloir pathway in yogurt fermentation
acetaldehyde - ANS✅✅major flavor compound in yogurt (minor flavors from dactyl and acetate)
UDP - gal-epimerase - ANS✅✅The enzyme of the Leloir pathway that converts UDP-galactose to
UDP-glucose is __________.
and answers graded A+
Pure culture advantages (wine making) - ANS✅✅-more consistent and satisfactory
-better flavor obtained from natural mixed cultures
-Saccharomyces cerevisiae commonly used
wild yeast disadvantages (wine making) - ANS✅✅-limited fermentation
-could be harmful to quality once activated in fermentation
Wine aging after bottling - ANS✅✅continues for several months depending on the type of grape
and style of wine
Steps of wine finishing - ANS✅✅1. racking
2. fining and filtering
3. preservatives
4. bottle
5. aging
Racking - ANS✅✅separation of wine from lees (sediment)
fining and filtering - ANS✅✅clarify and sterilize
preservatives - ANS✅✅sterilize and retain color
10^11-12 cells/ml - ANS✅✅density of frozen concentrate starter culture for milk fermentations
Phosphate's role in phage-inhibitory media - ANS✅✅chelates calcium required for phage
absorption
5 main genera that metabolize lactic acid - ANS✅✅Lactococcus, Leuconostoc, Pediococcus,
Streptococcus, and Lactobacillus
, Lactobacillus - ANS✅✅starter culture in dairy, pickles, beer, probiotic (high temp)
Lactococcus - ANS✅✅starter culture in dairy fermentations
Streptococcus thermophilus - ANS✅✅starter culture in dairy fermentation
Leuconostoc - ANS✅✅found in plants, vegetables, silage, milk, dairy, raw and processed meats,
sauerkraut, kimchi
pediococcus - ANS✅✅starter culture mainly in sauerkraut
metabolize glucose - ANS✅✅the purpose of the Leloir pathway is to
Key enzymes in Leloir pathway - ANS✅✅1. galactokinase (GALK)
2. galactose-1P uridylytransferase (GALT)
3. UDP-gal 4'- epimerase (GALE)
Galactokinase (GALK) - ANS✅✅galactose --> Gal-1P
Galactose-1P uridylytransferase (GALT) - ANS✅✅Gal-1P --> UDPGal
UDP-gal 4'- epimerase (GALE) - ANS✅✅1. UDPGalactose --> UDPGlucose
2. UDP- GalNAc --> UDPGlcNAc
Lactobacillus only - ANS✅✅genus that carries out Leloir pathway in yogurt fermentation
acetaldehyde - ANS✅✅major flavor compound in yogurt (minor flavors from dactyl and acetate)
UDP - gal-epimerase - ANS✅✅The enzyme of the Leloir pathway that converts UDP-galactose to
UDP-glucose is __________.
