Taste of scalded milk

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ValentinDavid
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Postby ValentinDavid » Aug 21, 2009, 11:55 am

Does anyone has a pointer to some serious source about the effect of heat on sweetness of milk? I read several times that scalded milk tastes bad because it is less sweet, but never had a really serious explanation. While lactose should react in a Maillard reaction creating some extra flavors, I think that the quantity of total lactose should not be diminished in a sensible amount.

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another_jim
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Postby another_jim » Aug 21, 2009, 1:06 pm

All sugared beverages taste sweeter as they get warmer. So it's quite striking, when I drink the remaining steamed milk from my morning cappa, how much the apparent sweetness decreases if I've gone a few seconds too long, and the milk has exceeded 150F, 65C. The taste goes from lush to dry in just a few degrees, whereas the pour is unaffected until one really overheats the milk

This is when the proteins just start to curdle, but when nothing at all is happening to the sugars. So I think protein curdling is the cause. However, I have no clue about the mechanism involved. It's noteworthy that one can still have a nice looking, pourable microfoam, at around 155F, whereas the taste has already gone dry.

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ValentinDavid
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Postby ValentinDavid » Aug 21, 2009, 1:55 pm

I found my answer:
http://www.foodsci.uoguelph.ca/dairyedu ... tml#cooked

But it does not say what temperature. And the taste should be as sweet. Just it should taste a bit like garlic, which is an unpleasant flavor.

Pasteurization is done at 75C. It should be noted that if it happens to you before 75C, then the flavor should happen at pasteurization. But as the link says, this flavor dissipates with time. So if you steam a milk at 70C, and put it in the fridge, you could resteam it the day after.

I read a paper claiming that foam is more stable for HTST milk at 85C while 65C for UHT (both whole). And from skim: 45C. The stability is the half-life. All the milks had around the same half-life at 85C. But note that your average temperature in your pitcher lower than the effective temperature at the output of the steaming wand. But it shows that like you said, temperature for the foam is still OK after 65C.

I will try to heat samples of milk heated at different temperature and cool them down at the same temperature, then do a blind test.

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JmanEspresso
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Postby JmanEspresso » Aug 21, 2009, 4:39 pm

IIRC, the Article on CoffeeGeek about Milk Frothing has a page or two going really in depth about milk proteins, why we use certain milks and why others dont work as well, and why we heat to the temps we do. Plus, its a good read over a vacpot of a nice rare coffee

CG Frothing Guide

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ValentinDavid
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Postby ValentinDavid » Aug 22, 2009, 10:05 am

Thank you. I already read it. But it is not as precise I want. Moreover it does not cite sources for all the claims, and it is oversimplified partly wrong. Though, it is a great manual for frothing.