Transcript Making yogurt

Lactic Acid Fermentation
 Yogurt
production demonstrates
fermentation by Streptococcus thermophilus
and Lactobaacillus bulgaricus
 Heated milk is inoculated and maintained at
a given temperature causing bacteria to
grow and ferment lactose, the suger in milk
 The bacteria produce lactic acid which
causes the milk to coagulate
 Food
grade containers, washed
 Food grade thermometer
 Hotplate
 Beaker tongs
 2 cup of milk
 1/3 cup nonfat dry milk
 2 table spoons yogurt
 pH meter
 Combine
milk with nonfat dry milk and heat
in water bath to 87ºC
 Hold at that temperature for 10 to 20
minutes
 Cool to 46ºC and record the pH of the
mixture
 Place the plain yogurt in jar and gradually
blend in the warm milk
 Cover and place in oven or incubator at 45ºC
 Allow
to stand undisturbed until the mixture
is firm when the jar is gently wiggled
 This may take as long as 6 to 8 houres