Hi, I’m teaching yr 12 Foid Studies for the first time next year. The students need to be able identify changes in chemical and/or physical properties that occur when cooking or preparing food. I don’t want to teach students the wrong thing, so my question is…does denaturation always occur with coagulation? Or can you have just one occurring on its own??
Denaturation can be caused by either mechanical shear( agitation), heat, acid, high salt concentration, and liquids like alcohol.
Coagulation happens after denaturation, Coagulation requires heat…
These two terms are interrelated and many times occurs simultaneously and mostly about protein behavior.
So as not to teach your students the wrong things then you should visually show to them through experiments using culinary techniques how the behavior of coagulation and denaturation occurs as you prepare food.
Can use milk and vinegar reaction as an example
Thank you both for replying. I appreciate it. Can I extend the question to ask whether meat always undergoes both denaturation and coagulation everytime that it is cooked. So sorry, I just find it hard to get my head around this topic.
Denaturation is for heat sensitive protein Like lactoglobulin and lactoalbumin in milk .they are settling with heated to 90 C approx.
Coagulation is for another protein with enzims or acidity change, yoghurd is akind of acidity change in milk. At ph 5.8 you can see the coagulation particulates with naked eyes.
On the other hands, with enzims milk protein coagulated at ph 6.8.
Protein other than lacto albümin and lactoglobulin , you can t denaturated with heating.
Yes, you can see danaturated protein on the surface of boiling water in which meat is heated. Another name of this proses scalding of meat in water. Every protein also the meat have izoelectric point at this point proteins zero electric. At this point only gravity is effect the proteins. İn meat , there is little water less than milk. You cant see cougulation.but meat texture or strenth of meat is descrease.you can do this change with acidity increase . İt can be direct acidification of meat with lactic acid, …or microrganizm_lactic cultures. Exp.mixing with yogurth…
Also you can mix meat with protein_ enzims.
You must know all proteins are soluable form in water as a compounds which make with mono-value metal ions.like K and Na compounds of casein.you can use natrium poli phosphate salt for this compounds
The OP is not technically advanced as we are ,that is why I kept technical jargon to the minimum.
What you are doing is sowing confusion instead of clarification according to the limits of layman understanding…
I accept your point.
Other than milk with vinegar (or lemon juice), you may also try various coagulants for tofu preparation:
To soymilk - add GDL - demonstrate slow coagulation producing soft tofu.
Do the same thing using CaSO4 and you can end up with Hard Tofu (or tawkwa).
Milk+ vinegar: You can ask students to measure the pH during your experiments and explain the iso electric point of proteins.