BACTERIAL GROWTH

PURPOSE : To demonstrate the effect that temperature has on the growth of bacteria.

MATERIALS : Milk

                        Measuring cup (250ml)

                        2 (500 ml) jars

                        Refrigerator

PROCEDURE : 

• Put a cup of milk in each jar
• Close each jar.
• Place one jar in the refrigerator.
• Place the second jar in a warm place.
• Examine the milk in each jar once for 7 days.

RESULTS : The warm milk has thick, white lumps in it and smell sour. The cold milk looks and smells like drinkable milk.

WHY ? Warm temperature promote the growth of bacteria that can cause food to spoil. Cooler temperature slow down the bacteria growth, but milk will eventually spoil if left in the refrigerator long enough. The bacteria are present and grow very slowly when cold, but they do grow.