LAB 3 food microbiology B

Question 1

what are the standards which the milk used in yogurt production held to

Answer 1

raw cow milk is used must have a ; low bacteria count , free of antibiotics, mastis milk, colostrum and rancid milk also there must be no contamination by bacterphages

Question 2

why must raw milk be pasteurized

Answer 2

raw milk must be pasteurized as it may contain pathogens such as E.coli remember though that the pasteurization does not completely sterilize the milk as bacteria whom are resistant to heat (or capsules ) may be able to persist

Question 3

what is the typical starter culture used in yogurt

Answer 3

Streptococcus themophilus and lactobacillus bulgaricus

Question 4

how do lactobacilli and streptococci work together

Answer 4

lactobacili liberates small peptides and amnio acids which aid in the growth of strep, strep in turn aids the growth of lactobacilli by producing formic acids from pyruvic acid (anerobic)

Question 5

what pH does the growth of streptococci stopped during yogurt fermentation

Answer 5

pH 5, for lactobacilli pH 4

Question 6

what is the diffrence between red and white wine

Answer 6

Red is made from red grapes this inculdes the entire grape

white wine is made form white grapes or red grapes which have had the skin removed.

Question 7

when does fermentation stop in wine production

Answer 7

when either all of the sugar is depleted or the alcohol content begins to kill the yeast fermenting cells.

Question 8

what yeast strain is used in this experiment

Answer 8

Saccharomyces bayanus

Question 9

how does a hydrometer work

Answer 9

it is used to measures the specific gravity of the solution, more alcohol found in solution the high the specific value

Question 10

should look over how to calculate the alcohol percent using hydrometer values

Answer 10

in lab 3 B presentation