Do an experiment and submit a lab report as required

Description

Students will prepare yogurt using milk and yogurt purchased from the grocery store.You need to buy the following materials.

Supplies:

• Milk (minimum of 1 pint), can be of any fat content
• Store bought yogurt with live active cultures
  • Remove ~ 2TBS, set aside, and allow to warm while heating milk
• Optional:
  • Dry milk powder
  • Heavy cream

Equipment:

• Pot to heat milk
• Spatula, spoon, or whisk to stir milk while heating
• Container to incubate milk
• A method to incubate the milk
• Thermometer
• Measuring cup

Directions:

Watch the video for details, the following is an overview of the process.

• Gently heat milk to a low simmer
  • 185F to 190F
  • Heat slowly and with stirring to avoid scorching milk on the bottom of the pot
• Hold at temperature for at least 5 minutes, or up to 30 minutes for improved texture
• After heating, cool milk to 105F-110F.If a thermometer is unavailable, allow to cool until milk feels slightly warmer than room temp
  • Placing the pot in a sink of cool water can help cool the milk more quickly.Be careful to not get any water from the sink into the milk.Similarly, the milk can be heated to 185F and then allowed to cool on its own.
• Once cool, pour milk into fermentation container if using a container.The milk could be fermented in the pot depending on how it is incubated.
• Add yogurt, or if using, yogurt cultures, and stir.
• Leave the milk/yogurt to incubate for 8-12 hours.
• After incubation, chill in a refrigerator for several hours prior to evaluating.

Lab Report:

Summarize the details for your yogurt.Be sure to include:

• The type of milk and how much
• What was used for inoculation
• What temperature was the milk heated at and for how long
• How was the milk incubated

Include pictures of:

• Your incubation set-up
• The final product

Answer the following questions:

• Describe the taste and texture of your final yogurt.What could be done differently to improve the quality for future ferments?
• Yogurt fermentation involves two key bacteria, S. thermophilus and Lb. bulgaricus.Describe the relationship between these two bacteria.Be sure to discuss the nature of their proto-cooperation and why these two bacteria are used together in yogurt.