1. The document provides instructions for making yogurt at home using milk, yogurt starter culture, and an incubator to maintain the proper temperature for fermentation. 2. Milk is heated to 185 degrees F then cooled in a water bath before adding the starter culture. The mixture is incubated at 110 degrees F for 8 hours to ferment and thicken into yogurt. 3. A mini lab experiment is described that varies the amount of starter culture used in different samples to determine its effect on the final yogurt product. Observations and conclusions are recorded.

1. Yogurt
You need:
- One quart of milk
- 2-3 tablespoons of yogurt (starter culture)
- Large pot
- Metal spoon
- Thermometer
- Small jars for yogurt
- Yogurt Maker/incubator/thermos
Instructions:
1. Read through the lab sheet and record your hypothesis.
2. Pour milk into large pot. Heat milk on medium high heat to 185°, stirring
constantly. Milk should get frothy at this temperature, but should not boil.
3. While milk is heating, prepare a cold water bath by filling the sink with
cold water and ice. Once the milk has reached 185°, remove pot of milk
from heat and place in cold water bath.
(many ovens have a “warm”).
b. Using a yogurt maker or incubator that will hold a constant
temperature of 110°.
c. Wrapping jars with heating pad.
d. Using our bread oven if it is at a consistent 110°. On a warm
summer day, the oven often hovers around this temperature.
8. Complete Results and Conclusion sections on lab sheet.

2. Mini Lab: Yogurt
Name:
Goal: To view food recipes as a scientific procedure. To experiment with a
recipe.
Question: How does the amount of starting culture used affect the end product
in yogurt?
Hypothesis:
Background:
Milk is perishable and spoils quickly. Bacteria spoil milk by feeding on the
lactose sugar. It is possible to preserve milk with refrigeration and fermentation.
In fermentation, bacteria turn lactose into lactic acid. As a result, milk becomes
acidic and prevents other bacteria from growing in the milk. Acidic milk
becomes solid (yogurt) because a milk protein named casein is insoluble in
acidic solutions.
Results: Use this space to describe your observations. Be specific and make
sure to compare yogurt samples to each other.
Conclusion: Briefly conclude your experiment by answering the question. Also,
ask a future question.