Cooler temperatures help milk kefir grains grow

Rather than reusing kefir grains, I have been saving a cup from a previous batch to start a new one. The batch is probably not diverse since in the summer I made it in a very warm room. If it has lost diversity, can it regain diversity if it is later cultured in cooler temperatures?

I purchased dehydrated grains and have been using 1% pasteurized milk from Giant’s store brand. It consistently thickens in 24 hours. I swirl a whisk to mix it after straining the mixture. I reserve a scant 1/4 c. For the next quart and use cold milk and whisk it to mix. I keep it around 70 to 73 degrees.

Hi Cynthia – Yes, raw milk tends to make a slow bacteria rich ferment no matter what you do. It can be more tricky to ferment with pasteurized milk as it can ferment faster and get more yeasty over time. High quality milk with minimal processing does help. Cooler temperature with less grains and occasional stirring helps as well.

I used to have a wonderful kefir culture, where a large quantity of grains were produced but it did not over ferment the ferment. That was when I was using mostly raw milk. The grains I now use seem to ferment the milk way too fast with very few grains. Is it because I use pasteurized milk? I want to reconstruct the ferment I previously had with my new grains. Do I need to lower the yeast?

Hi – Thanks for all the really helpful info. I recently got some grains from a friend and re-started culturing milk kefir. I have a thriving water kefir culture, so that’s not a prob. I’m in Singapore where temperature is typically betwn 27 to as high as 33 deg C during the day. I find in fact that the milk kefir culture time is markedly shorter than 24 hour. If i leave for even 12 hour the grains seem to over-culture into curds and whey. So i watch it and harvest maybe less than 10 hours. But I struggle with making the kefir milk more creamy. The grains too seem small but I know they are active bec they grow, and fermentation does happen. Can you suggest pls what I shld do to make the milk creamier? Should I stick to culturing in fridge? Thank you

Hi Louise – Great question! I’ve also heard that diversity can sometimes be bad, but I believe that’s mostly in reference to lab based probiotics. Those who combine probiotic strains, such as in probiotic pills, sadly don’t really know what they are doing. The probiotic industry is very young and the microbiome is incredibly complex, so its really hard to know how different strains that are combined really work. Kefir is different though. They are in an environment that’s already in a strong optimal balance. The natural diversity in grains works well together and it would make sense that they would work well within your digestive tract as well.

I have heard it suggested from a microbiologist that some people believe that having more diverse microorganisms may not necessarily be good, as they may actually work against one another. Is there any evidence that more is better?

Hi Elisabeth – Yes, fridge fermenting will lower the overall diversity of the ferment. That doesn’t mean that its unhealthy or bad, its just not potentially as diverse as a room temperature ferment. It’s still good and there’s no reason to stop if it works so well for you.

I have been fermenting mine in the fridge. It takes about 3 or 4 days and I do this as I am out so much that I can’t monitor the fermentation. Am I losing some of the goodness?

Hi Leda – Milk kefir should be pleasant if done right. If you are needing to flavor it just to drink it, its probably not balanced right or its over fermenting. Try using less grains and more milk or help balance them or try new grains. Sometimes grains that were dried have trouble getting back to full health. As far as the milk, you can use milk directly out of the fridge. It’s typically the easiest and safest way (there may be more spoilage bacteria with pasteurized milk if you let it sit out too long). Warmer milk may help kick start the process a bit but the overall ferment won’t change too much.