Boiling before Kefir?

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Boiling before Kefir?

Postby dri on Tue Sep 12, 2017 11:25 am

Been making Kefir for about a month. I've done lots of experiments but still have many questions. Figure I can use the wisdom that others have gained and learn faster. I'll post some of my own experimental results in other posts.

In this question, I'm aiming at a boiling for a thicker fat-free or low-fat kefir for diet reasons. I'm not going to whole milk or cream for my daily kefir, though I might use it on special occasions;-0.

In making yogurt its common to boil it first, and my reading says that the point it to denature the albumin and lactoglobulin whey proteins so they can get caught up in the structures formed by the yogurt. So it stands to reason that there is much more whey when making kefir because these proteins are water-soluble and not impacted by the kefir fermentation/PH. The α-lactalbumin, which is about 20% of whey is very heat stable so still there even after heating to modest temperatures, but gets "bound" in the casein that is also impacted by heat Heating impacts where the casein can bind together making it better at encapsulating whey. According to On Food and Cooking ( Harold McGee, pp 48)

"These treatments improve the consistency of the yogurt by denaturing the whey protein lactoglobulin, whose otherwise unreactive molecules then participate by clustering on the surfaces of the casein particles. With the helpful interference of the lactoglobulins, the casein particles can only bond to each other at a few spots, and so gather not in clusters but in a fine matrix of chains that is much better at retaining liquid in its small interstices."

As an aside for others, my reasoning is that this impact on casein binding also likely explains why I sometimes got a nice jello-ish blob of kefir with little whey from a low temp ferment with no agitation, but then after straining/blending it, it separates with a good bit of whey even though no whey was visible in the original jar/blob. I guess the blending upset the larger casein bonds holding the whey and they did not reform as long bonds but instead found short bonds that did not hold the whey, thus allowing separation.

So has anyone tried making kefir after boiling milk like for yogurt? I know it will be a more work to boil/cool it but figured it would not hurt to ask about temps used and how long and how much is gained. (For yogurt I've seen different recommendations from 195F for 10 min to 180F for 30min to, to using a slow cooker for hours. Yogut people cool to 120 or 110F, but what temp do I cool to for kefir (80F?) Lots of potential variables to interact so Any recommendations what works best, especially for non-fat milk kefir?
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Joined: Sat Sep 09, 2017 10:51 am

Re: Boiling before Kefir?

Postby dri on Sat Sep 16, 2017 4:41 pm

Well I figure I'll post results from my first experiment.

I used the microwave to heat the milk directly in the ball jar. non-fat milk was zapped for 5:00, tested for temp (170) stirred then zap for 1:00 (milk boiling at edge), tested for temp (180), stirred then zapped for 1:00, (boiling along edges again), temp 190. Let sit for 5 min, temp down to 183, zap for 30 seconds again (back to 192), then let cool down.

Once temp was reasonably cool, put in the fridge for a while as I did not have a batch ready to go.

Then I put in my kefir grains and let it start for about 4 hours, then in the fridge Because days are hot, I only ferment early in morning or in the evening). Then it was on the counter for about 20 more hours over the next 2 days. Whey separated, but on the top which seemed a bit was odd.

While there was a lot of visible whey, it never formed curds. I would shake it and let it stand more and see a bit more whey after a while,but still no curds. But with the amount of whey I figured it was done.

Strained it (using coffee filter given it seemed thin). Total volume of solid kefir was bit less than a normal batch and whey a bit more, but the kefir was not lumpy and had a nicer yogurt texture. No fizz but that is probably because I kept it fermeting only when it was < 70F (which helps it be thick, or so I read).

Overall about the just a little less strained kefir. While maybe there is more protein in it, I cannot really tell. So the only reward for the added effort of heating was the improved texture.

I'll do more experiments and report (maybe I did not have it at 190 for long enough.)
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Joined: Sat Sep 09, 2017 10:51 am

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