Lactic Acid Fermentation Making yogurt Lactic Acid Fermentation

Introduction 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

Materiales 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

Procedure 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

Procedure 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