daily tasting five: milk temperature

I’ve wanted to taste test too-hot milk for a while, and this tasting-a-day project has been a perfect excuse to finally do it.

This experiment was pretty simple. I steamed milk just as I always do, then I steamed milk the way I would for an “extra hot” drink. I took the temperaturein the pitcher after steaming. It turns out I steam milk pretty consistently to around 145 degrees Fahrenheit. My extra hot milk was 160.

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The extra hot milk was actually worse then I expected. It smelled weird, for lack of a better term. I’ve heard “burnt” before, but I don’t think that’s quite right for describing the smell. I’ve also heard “burp” which I think might be getting closer. Someone at the Newbury St. ERC suggested that it had a “sour milk” smell. In the mouth, the sweetness I usually associate with steamed milk didn’t have much of a presence.

The “normal” milk at 145 degrees was sweeter and didn’t smell weird.

Buuuuut I decided to go cooler and see if it got still better. I steamed milk to 140 and 130. I didn’t notice a change in smell so much, and no one else who tried mentioned a change in smell, but the cooler milks were notably sweeter. The milk at 130 reminded more than one person of melted ice cream and was superdelicious. I’m not sure how much of that is the tasting temperature and how much is actually irreversible after the milk is heated. In other words, how much would the milk steamed to 145 taste like the milk steamed to 130 if it were cooled to the same temperature?

Hm…sounds like the makings of a future tasting experiment….

About barnwolf

head barista for pavement coffeehouse and erc boston
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4 Responses to daily tasting five: milk temperature

  1. D. Evans says:

    I love all the experimenting you’re doing! That’s the best way to learn and gives me clause to revisit some experiences I’ve had.

    From what I understand, the carbohydrates/sugars in milk (lactose and glucose) are wrapped in protein skeins, like yarn. Proteins start breaking down, or denaturing, at about 100F, exposing the sugars to roam about more freely. At 150F the proteins start to denature rapidly, exposing even more sugars. At 185F, about 95% of proteins are completely denatured. Aside from the hydrophobic affect of some of these proteins (milk-water and fats separating quickly), there should be not a lot of taste due to these elements.

    The Lactose and Glucose, however, being fats, melt under heat. They turn to oils, trap the air and create micro foam. Perhaps a test of letting it separate and tasting the liquid vs oil/air mixture would be cool? Basically, 130-140 seems to be the ideal balance of exposed sugars vs whole proteins in the mix. Once a protein is denatured, though, there is no reforming it even as it cools. There’s a word for that; when a compound can be broken but not reformed naturally, I forget.

    On a side note and for awkwardness’ sake, I just read that guinea pigs, whales, and seals have about a 50% fat content in their milk, where as even the Jersey’s from High Lawn have only 5.6%.
    Narwhal breve?

    • barnwolf says:

      Thanks Dylan! That’s a way clearer explanation of milk chemistry than ones I’ve heard in the past. I definitely have a ton to learn as far as that stuff goes.

      If you do the separated milk test, let me know how it goes. I may try it if I have some free time today.

      And narwhal breve, eh? Maybe we should be investing in narwhal farms? If this is the future of coffee, we probably want to get in on it now.

    • JS says:

      I’m no milk scientist but I’m pretty sure lactose and glucose are sugars not lipids. Glucose is a monosaccharide, whereas glucose is a disaccharide comprised of glucose and galactose.

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