Kefirs are a fermented dairy product that typically contain a dozen or more bacterial species and several fungal species. Kefirs are among the richest source of probiotic microbes, more than the several bacterial species provided by yogurts.
Unfortunately, fermentation time is something that manufacturers cut short, as it slows down production. Imagine you have a shoe factory. Making one pair of shoes requires 48 hours, while a competitor can make a pair of shoes in 4 hours—who will make more money? The manufacturer who makes shoes in less time is more likely to make money, as they can produce shoes in larger volumes over a shorter time period. The same phenomenon applies to fermented foods: Commercial manufacturers will use the shortest time possible that yields an end-result that is acceptable in taste and texture—but not necessarily in bacterial counts. Commercial yogurt fermentation, for example, is typically only 4 hours in duration, compared to the 36 hours we use for L. reuteri fermentation. The massive increase in bacterial counts begins at hour 30, with exponential increases to nearly 100 billion bacterial counts by hour 36. This is why commercial yogurt yields almost no real health benefits. It’s NOT about only taste and texture; it’s about bacterial counts. The same issue applies to kefir. The Wallaby product is fermented for 8 hours or longer (they won’t specify precisely how long, as they claim it’s proprietary).
So most commercial kefirs have been fermented for as little time as possible. You can improve on this by simply leaving your kefir container out on the counter for another 48 hours or so to allow further fermentation to proceed. But here is another little strategy you can follow: re-ferment the kefir. And, by doing so, you can put the long list of bacterial species to work to replace the need for a probiotic supplement.
This is a problem, however, if you obtain kefirs that contain fungal species such as various Saccharomyces, as they ferment to ethanol, i.e., alcohol. But you can find commercial kefirs that have many bacterial, but no fungal, species, such as the product shown above, the Wallaby brand of kefir. (No strain specified, of course, as is typical for fermented foods.) Among the bacterial species included are:
- Streptococcus thermophilus
- Lactobacillus bulgaricus
- Lactobacillus casei
- Lactobacillus acidophilus
- Bifidobacterium lactis
- Lactobacillus rhamnosus
- Lactococcus lactis
- Lactococcus cremoris
- Lactobacillus paracasei
- Lactococcus lactis subspecies lactis biovar diacetylactis
- Leuconostoc mesenteries subspecies cremoris
- Lactobacillus delbruueckii subspecies lactis
There are other brands of kefir that likewise contain many bacterial species with no fungal species such as the Lifeway brand that contains:
- Bifidobacterium breve
- Bifidobacterium lactis
- Bifidobacterium longum
- Lactobacillus acidophilus
- Lactobacillus casei
- Lactobacillus cremoris
- Lactobacillus lactis
- Lactobacillus plantarum
- Lactobacillus reuteri
- Lactobacillus rhamnosus
- Streptococcus diacetylactis
- Streptococcus florentinus
Compare just these two brands and you can appreciate that kefirs can be quite different in microbial species composition with overlap in just four species. The Wallaby product, for instance, contains L. paracasei that can suppress pathogens such as Salmonella and H. pylori, while the Lifeway product contains a strain of Bifidobacterium longum that may provide emotional health benefits. Ferment either of these kefirs and you have a broad collection of healthy microbes. You can even combine a little of each kefir and re-ferment to yield a kefir with 20 different microbial species.
To re-ferment kefir to amp up bacterial counts:
- In a medium-sized bowl, combine 1-2 tablespoons of kefir, one quart of organic half-and-half or whole milk (or your choice of casein A2 source), 2 tablespoons prebiotic fiber (e.g., inulin, raw potato starch)
- Mix thoroughly (using spoon, not a mechanical blender or mixer)
- Ferment at 106 degrees F for 36 hours (high enough to allow species like Lactobacillus acidophilus to reproduce but not high enough to kill heat-sensitive species like L. reuteri)
The end-result will be thicker than the original kefir, given our prolonged fermentation to jack up bacterial counts.
I paid around $4 for each of the commercial kefirs. It means that a couple tablespoons of store-bought kefir can yield months and months of probiotic and save you a lot of money by not having to buy costly commercial probiotics.
Why can’t we combine both L. Reuteri and the kefir to make one batch of yogurt instead of making two separate batches of yogurt?
Susannede wrote: «Why can’t we combine both L. Reuteri and the kefir to make one batch of yogurt…»
Mixed cultures raises questions of: common temperature, common substrate, competition, relative growth rates, bacteriocins, etc. (and L.reut does generate bacteriocins).
Heirloom kefir grains are indeed mixed, but being heirloom, have a track record of the microbes getting along with one another. Adding new bugs pre-ferment becomes an experiment.
With retail live culture fermented foods, I have to wonder if the final product is from a single ferment batch, or whether the various species and strains are cultivated separately, and then blended at bottling. I imagine Dr. Davis has made inquiries along these lines. It would inform further fermenting of the finished product.
re: «…instead of making two separate batches of yogurt?»
I’m making 3 different yogurts presently, soon to be 4, and I am not at all tempted to try to brew all at once. Heck, two want 100°F, one wants 105, and the next is 122.
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How much do you eat of each type every day?
Susannede wrote: «How much do you eat of each type every day?»
I’m probably consuming ~⅓ cup daily in my morning smoothie.
Typical consumption apparently ranges from ¼ cup to 1 cup per day, but I don’t think we really know if any benefits scale above ¾ cup/day.
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Wow, so if I make the third yogurt and add it into my regimen each day I could be consuming almost 1.5 cups of yogurt a day. That would be 1/2 cup per type of yogurt. Seems like a lot of extra dairy but I guess the benefits of the extra probiotics, etc will be worth it.
Susannede wrote: «…so if I make the third yogurt and add it into my regimen each day I could be consuming almost 1.5 cups of yogurt a day.»
Ummm, don’t think so. I actually don’t know what other multi-yogurt brewers are doing, but I’m only consuming ⅓ cup/day, rotating through each, one per day.
Another approach would be to mix them after fermenting, and consume the blend. Fermenting a blend, however, is apt to fail.
If we end up at 6 or 7 different recipes, I suppose we’ll need some guidance on consumption.
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Ok, here we go… I make my own kefir using live culture that I have nurtured for several years. I ferment my milk for a minimum of 24 hours. Sometimes I will do a second fermentation. Does this Kiefer have any probiotics in it? How would I know if it has any live bacteria in it and what they would be? I don’t add any prebiotic fiber’s.
What do you think about doing a second fermentation and adding prebiotic fiber’s? How do I know my Kiefer is providing any benefit?
I just started a google search to answer my own question.
Ok so Ive got my answer. So I guess my new question would be, can I do a second ferment and add some probiotics?
Sylvia wrote: «…can I do a second ferment and add some probiotics?»
Adding any other live organisms prior to a ferment introduces completely unpredictable variables.
You can add pretty much whatever you like to a finished ferment, just for serving.
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Just to clarify… Each subsequent batch of kefir should be started with a few tablespoons of the previous (re-fermented) batch, NOT the original commercial/Wallaby one. (Which I assume will have long since gone bad even if refrigerated). Correct?
Also… is the re-fermented kefir still a drinkable consistency or does it become a “yogurt” like the L.Reuteri version?
Hi Joe,
I’ve got a batch fermenting now. I used three cups of half and half,
1 1/2 tablespoons inulin, and 3 tablespoons of my homemade kefir at 104 deg (Luvele max temp).
At 24 hours it was thick on top with a lot of cracks and a lot of whey underneath. It has a Nice yeast aroma. I know what bad kefir smells like and this is not that. So 8 more hours to go.
If this turns out edible I will save the whey for another batch.
I use frozen whey from batches of LR as my starter door LR.
Sylvia wrote: «I use frozen whey from batches of LR as my starter door LR.»
As do I, but the strains of L.reuteri and L.casei that we use are known to tolerate freezing (and may well be conserved in liquid nitrogen).
I’ve not made kefir, though, and don’t personally know if the “grains” (collections of varied microbial species and strains) survive freezing.
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Bob,
Kefir grains can be frozen for long term storage (Cultures ForHealth) but not sure about the whey from fermenting the kefir. I will have a lot of whey from this batch so plan on conducting some experiments.
So I fermented homemade keifer in the Luvel at 104 deg at 36 hours. I used 3 cups half and half, 1 1/2 tablespoons inulin and 3 tablespoons homemade keifer. The consistency is thick. It is very tart which is an acquired taste. I’m not really liking the taste. As it is, I dress up my keifer when I drink it so doubt I will eat the fermented product as is.
What’s the problem with alcohol? Is it simply to avoid alcohol, or does it affect the outcome of these instructions?
By the way, Lifeway’s website lists Saccharomyces Florentinus in its organic plain unsweetened kefir.
Mark Simons wrote: «What’s the problem with alcohol? Is it simply to avoid alcohol, or does it affect the outcome of these instructions?»
The latter, in the context of fermented foods. Any alcohol produced by yeast (fungal) metabolism is almost certainly going to kill off desired bacteria, and eventually kill off the fungi as well.
Consumption of purpose-made alcoholic beverages is compatible with the overall program (unless it is a problem for any specific individual, or a suspect in weight loss stall), in the range of 1-2 standard drinks per day, and with attention to net carbs (esp. added sugars), avoiding grain-sourced content, and avoiding various often-undeclared additives.
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