Make Cheese!
 We can learn about enzymes and biotechnology by making cheese! According to legend, cheese was discovered thousands of years ago by a shepherd carrying goat's milk in a pouch made from the goat's stomach. A substance in the lining of the goat's stomach called rennet contains an enzyme, chymosin, which coagulates milk. During the shepherd's travels, heat from the sun activated the enzyme in the goat's stomach and turned the milk into curds and whey. Whey is a thin liquid, and curds are chunks of cheese!
Today, instead of using the lining of a goat's stomach to make cheese, we can make the enzyme using genetically engineered bacteria in the lab. This is biotechnology - the use of living things as tools!
We can make our own cheese using a rennet tablet (which may be purchased or ordered from a grocer), milk, heat and a few simple materials. Learn more about cheese!
 To do this experiment you will need:
1 gallon Crock pot
1 gallon pitcher
3 packets nonfat instant milk (enough to make 3 quarts)
9 cups warm water
4 cups buttermilk
½ rennet tablet (can be found in most grocery stores)
¼ cup cool water
Cheesecloth
Thermometer
Colander
Optional:
Half-and-half
Herbs and crackers
½ teaspoon of salt
- Prepare nonfat instant milk by filling a pitcher/container with 4-½ cups of warm water. Pour in nonfat instant milk and stir to dissolve. Fill the pitcher/container with the remaining 4-½ cups of water.
- Add buttermilk (room temperature) to the crock pot and turn on high. Buttermilk increases the acidity and helps the enzyme work well.
- Fill the remainder of the crock pot with the nonfat instant milk prepared above, and leave about 1 inch of headroom in the crock pot. You may have a little instant milk left over. Stir until temperature of the mixture reaches 90° F, then turn the crock pot off.
- Dissolve ½ rennet tablet in ¼ cup cool water. Rennet contains the enzyme that will turn the milk into curds.
- Add rennet solution to crock pot mixture and stir in an up and down motion for two minutes. (Stirring in a circular motion slows the enzyme down.)
- If mixture is still at 90° F, leave the crock pot off. Otherwise, bring the temperature back up to 90° F and turn the crock pot off.
- Put the lid on the crock pot and let sit for 40 - 45 minutes or until the milk forms a solid curd that shows a clean break. If curd is like soft yogurt, wait a little longer.
- Once the curd is somewhat firm, use a knife to break the curd into smaller chunks. This part is not critical as stirring will further break up the curd. Turn the crock pot on high and stir slowly and gently in up and down motion. The curds and whey (liquid portion) will separate. Stir enough to make sure the curds are not sticking together.
- Once a temperature of 102° - 105° F is reached, turn off the heat. Do not let the temperature go over 105° F. Stir for about five more minutes.
- Line the colander with cheesecloth and put over the sink. Pour the mixture into the colander and let the whey drain for about five minutes. Rinse the curds in cool water to remove more of the whey.
- Wrap cheesecloth around curds and press out the whey. Put the cheese in a small bowl and break up or cut with a fork to look like cottage cheese.
- If you want, add ½ teaspoon of salt, a small amount of cream and herbs for flavor. Serve your cheese on crackers. Store the cheese in your refrigerator. It is also good for dishes such as lasagna or crumbled on salad.
*Adopted from Utah Education Network, "Cheesy Tool...Biotechnology," by William Deimler.
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