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Questions for Callaway
Triste:
Okay, here's another one (take your time):
When making homemade yogurt, why do you have to heat the milk to just below boiling, then cool it down to lukewarm (100 to 110 degrees)? This makes no sense to me since the milk we all use is already pasteurized.
McGiver:
callaway,
what is your level of education?
Callaway:
--- Quote from: Triste on August 28, 2006, 01:31:32 AM ---Okay, here's another one (take your time):
When making homemade yogurt, why do you have to heat the milk to just below boiling, then cool it down to lukewarm (100 to 110 degrees)? This makes no sense to me since the milk we all use is already pasteurized.
--- End quote ---
Milk is pasteurized to reduce the bacterial content to 0.00001 of the number of bacteria in unpasteurized milk. If you wanted to make yogurt from raw milk, you would need to pasteurize it first by heating it to 161.5 degrees Fahrenheit and holding it at this temperature for at least 15 seconds. Heating the milk to just below boiling changes the structure of the milk protein so that that it does not coagulate and make curds and whey instead of yogurt. You have to cool it off to lukewarm before you inoculate it with the yogurt culture so you won't kill the bacteria.
Sorry, but the molecular diffusion question is difficult for me to get a good answer for. Molecular diffusion of the chlorine bleach into still water in the water tank would happen very slowly and that is why stirring it is recommended. Actually, if the water tank is subject to temperature fluctuations between day and night, you would get convection currents from the colder and warmer water and also if you use water from the tank and add water to the tank periodically, that would mix the water more quickly than molecular diffusion. I don't know how to calculate these effects in closed form, and a computer model would require a lot more information.
McJagger, I have a Master's degree in Chemical Engineering.
Triste:
(Bows down before Dr. Callaway)
Thank you! Beautiful answers.
Question: My master's program advisor is so disorganized and incompetent that both my learning and grades are at risk. I have to take at least 6 classes taught by her. Should I change tracks to get out of her realm; should I drop out of school entirely; or should I stick it out with her, complaining and documenting everything?
Callaway:
Tell me more about her. What are your problems with her?
Why is she your master's program advisor? Did you choose her? What are her responsibilities as your advisor?
If the classes are required for graduation, then can you take them from someone else, or is she the only person who teaches them?
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