Making yogurt to amplify counts of the bacteria Lactobacillus reuteri is really very simple. We do this because the ATCC PTA 6475 and DSM 17938 strains of L. reuteri provide a ton of health benefits that includes increased skin/dermal thickness and reduction of skin wrinkles, increased or preserved bone density, reduced appetite, increased muscle, massively accelerated healing, increased libido, and may even prevent recurrences of small intestinal bacterial overgrowth (SIBO), given the organism’s potential to colonize the upper gastrointestinal tract.
But some people struggle to obtain the thick, delicious yogurt that most of us create and thereby are unable to enjoy all the spectacular health benefits of this targeted probiotic strategy. (It’s NOT about the yogurt; it’s about increasing counts of this bacterial strain—the yogurt is just the vehicle we use to accomplish this.)
If you are encountering difficulties in making the L. reuteri yogurt, consider these troubleshooting items:
- Temperature—Unlike most other lactate-fermenting species used to make yogurt, L. reuteri grows best at a lower temperature of around 100 degrees F. Microbial die-off begins at 115 degrees, with virtual wipe-out of the organism at 120 degrees. Unfortunately, many heating devices, such as yogurt makers or Instant Pots, either do not specify the temperature and/or are set inaccurately and generate temperatures of 120 degrees F or higher, killing your bacteria. If you fail to see any fermentation, i .e., no thickening occurs after 12-16 hours, check the temperature with a thermometer. You may have to use another device or do as I do: Use the oven by turning onto any temperature, e.g., 300 degrees, for 60 seconds, then turn off; repeat every 4 hours or so. As imprecise as this seems, it works great and you do not need to purchase any devices. (At night, heat before bedtime, then again when you awake—no need to get up in the middle of the night.)
- Not enough prebiotic fiber—We use 2 tablespoons prebiotic fiber, such as Bob’s Red Mill Raw Potato Starch or powdered inulin, per quart of liquid. Omitting this step will yield a thinner end-product with markedly lower bacterial counts and thereby not yield the benefits we are looking to obtain.
- Ferment longer—Although you may have yogurt after 12 hours, this is not long enough to generate the magnitude of bacterial counts we desire in the trillions. (See the Arithmetic of Yogurt blog post.) We therefore aim to ferment for 30 to 36 hours, then refrigerate.
- Use a thicker starting liquid–I like starting with (organic) half-and-half, as the 18% fat yields a cream cheese-like end-product, thick and rich. Cream also works, but yields something close to the consistency of butter, too thick for my taste. Full-fat milk (cow, A2 milk, goat, sheep) is okay, but expect a thinner end-product, similar in consistency to store-bought yogurt. Avoid use of skim, low-fat, 2%, or non-dairy almond, hemp, soy milks, as they are too thin and, of course, we never limit fat on the Undoctored lifestyle. Coconut milk (canned, never carton) can be used, but be sure to emulsify the milk (e.g., stick/immersion blender) prior to adding starting culture and prebiotic fiber; this prevents separation of the fat.
Recall that strain specificity is important: while there are other strains of L. reuteri available, we have no evidence to suggest they yield similar benefits. So, for assurance of full benefit, stick to the strains that we know yield these effects, the L. reuteri ATCC PTA 6475 and DSM 17938 available from BioGaia.
Question: my last batch, I forgot about it and “cooked” it for 45 hours. It had a skin that was mottled brown (which tasted good and obviously didn’t kill me … I ate it yesterday 😂). The yogurt itself was good-tasting but had far more whey than normal … so, does it damage the yogurt to over-process it???
Bonnie wrote: «…“cooked” it for 45 hours. … does it damage the yogurt to over-process it?»
The two major concerns with extended ferments are:
• substrate exhaustion, and
• opportunistic contamination.
If the over-fermented batch has no obvious growths/molds/discolorations on the top, and still smells like and tastes like a 36h batch, it’s probably safe to consume.
What it might not be, however, is suitable for use as starter for subsequent batches.
Outcome tip: set a smart phone alarm.
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Not trying to be contradictory, but you say that bacterial counts are higher with the addition of prebiotic fiber. My understanding is that you have not tested the bacterial counts at all. How do you know the prebiotic fiber isn’t simply acting as a thickener???
After having made my yogurt for at least 20 times, I was wondering why it is not as thick as the picture. So I just did a temperature test. It is reading 121 degrees in my new Proctor Silex machine, I wonder if I should send it back? Does anyone have an idea of a better machine? It does taste like greek yogurt though.
Barbara wrote: «So I just did a temperature test. It is reading 121 degrees…»
That’s a problem. And frankly, that’s a problem for use of that even in conventional yogurt with conventional culture. I stopped using our Cosori pot for anything but the pasteurization cycle due to over-temp.
re: «…in my new Proctor Silex machine, I wonder if I should send it back?»
What did the Specifications promise before you bought it? (chances are they were ominously silent on this critical matter). That aside, does the pot have any capability to run at user-defined temps? Ours does, but only 4 hours at a time, which is unacceptable for a 36 hour yogurt.
re: «Does anyone have an idea of a better machine?»
Yes: none of the above. Here’s what I use. For the last couple of batches, it’s been holding 100°F±2 quite nicely.
re: «It does taste like greek yogurt though.»
That makes me wonder how accurate your thermometer is. The 121°F needs to be cross checked before throwing in the towel on that pot. Alternatively, you can check the thermometer itself with some reference temps (adjusting for altitude). Boiling distilled water should be 212°F. A distilled water ice bath should be 32°F.
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Thanks Bob, there where no specification listed for the temperature. I of course thought everyone knew not to cook over 120, clearly Proctor Silex does not know how to make yogurt. I noticed on a recent post, someone was talking about Anova cooker. I am researching this device for temperature accuracy.
The best I’ve been able to find is one by Luvele. It’s got 3 temperature settings and a 24 hour timer. But it’s also $80. I think I’m gonna try a glass jar in my dehydrator. That’s a chunk of change.
Sheryl wrote: «It’s got 3 temperature settings and a 24 hour timer. But it’s also $80.»
Don’t spend a dime unless you are highly confident that the device is suitable for this use.
It needs to specify the available target yogurt temps. I’m presently thinking that something between 97°F(36°C) and 105°F(40.5°C) is desired.
☑ It needs to specify how tightly it regulates the temp. It it wanders below 95F or above 110F, reject.
☑ It needs maintain that temp for at least 10 hours (so you don’t have to get up in the night to reset it).
☑ This may describe exactly zero not-so-smart pots with so-called yogurt cycles. Sous vide cookers (like Anova) may suffice, but I’d only do that if I had other uses for the machine.
re: «I think I’m gonna try a glass jar in my dehydrator.»
May run too hot also. Whatever anyone uses, start with a “batch” that is just plain water, and see what temp it runs/holds for several hours.
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I concocted a system that uses a 2 qt. stoneware crock standing on a piece of foam insulation and wrapped in a heating pad. Has worked perfectly for my Greek yogurt for years..!!
I did my L reuteri the same way and left it 36 hours the first time… Decent result although not quite as think as advertised (full-fat milk). Second batch I only left 12 hours and got much the same thickness. Third batch, I left 7 hours… A little thinner but still okay. My goal is to add the L reuteri starter to my Greek starter (that is perfect at 105-110 deg. for 7 hours) to get the benefits of both. I’m wondering if the L reuteri bacterial count will be there if combined and the fermentation is only 7 hours…?
Valerie wrote: «I concocted a system that uses a 2 qt. stoneware crock standing on a piece of foam insulation and wrapped in a heating pad. Has worked perfectly for my Greek yogurt for years..!!»
Neat. Of curiosity, when you probe the temperature, do you see much gradient between the outside edge and the center? My concern would be that if it’s getting to 105°F in the center, it might be much higher nearer the heat source.
re: «My goal is to add the L reuteri starter to my Greek starter…»
Hard to say what you’re going to get if you do that. The Greeks might out-compete the L.reuts.
re: «I’m wondering if the L reuteri bacterial count will be there if combined and the fermentation is only 7 hours…?»
Doubtful. I’ve been using one (slowly thawed) ice cube of frozen whey (from a 36 hour batch) as starter for months now, and it works reliably. When I ran the numbers for my technique, it appeared that it takes at least 18 hours for one cube to contain the 1B CFUs I started with (and that’s with no competing species).
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Thanks for sharing this. I may buy the 2L one . I have been using my instant pot, but now I’m afraid it may be too hot. My batches come out creamy and delicious. I’m curious if the taste would change using this maker instead of my instant pot.
Thank you for publishing this troubleshooting post. I think that I have been skimping on the pre-biotic, which was creating problems. My most recent batch (completed last night) is much thicker than previous batches. I started with a completely new batch with freshly crushed tablets and more inulin a cup than I had been using before. This batch had about 1/3 cup for 1 gallon of half-n-half–not quite enough for 36 hours of culturing, so I stopped after 24 hours. The resulting batch was quite thick, similar to a soft cream cheese, similar to Dr. Davis’s blog pictures. My earlier batches (after 36-42 hours of culturing) were a lot thinner (like store-bought non-Greek yogurt) with a lot of separation between curd and whey). It was different and I still enjoyed eating it.
My Instant Pot Duo is culturing yogurt at 106F degrees. I checked the IP manual which shows that the temperature range for “yogurt normal” should be between 96.7F/36C and 109.4F/43C.
Hi
I have been using the luvelle yoghurt maker for 6 weeks/ 9 batches. Perfect results every time. 40 deg C for 24 hours.
Ok now I understand about the temperature of the yogurt itself. I had checked the temperature of my yogurt maker several times, empty, with an oven thermometer and it was below 110 degrees, however yesterday when my yogurt was getting thinner instead of thicker during the cooking I checked the temp and sure enough 123. Needless to say this batch was almost all watery. I have been using the EuroCuisine and I’ll see if I can get my money back. I’m going to try the oven now!!! Thank u Dr Davis!
Interesting… Thanks Bob.
I did check the temperatures – center vs. the edge of the crock closer to the heat source: Center was 110 and the edge was 113-115.
Curious if anybody has had any success using canned coconut milk? I used 26 ounces of the coconut milk added a tablespoon of raw sugar 2 tablespoons of Inulin and 10 of the recommended tablets crushed. I did a small mixture with the coconut milk with my immersion blender and then added it to the rest of the coconut milk and continued with the blender. I am on day three with 1 day to go ( you recommended 4 days with coconut milk) and have been doing the oven approach very consistently….90 seconds on every 4 hours. I realize that it’s not about the yogurt, but it’s thin. Because I tend to break out around my mouth with half-and-half or heavy cream I went the non-dairy approach. I don’t care that it’s not thick I’m just hoping that the bacteria count is high enough. Also, I wish you had stated how many servings you get because if you’re eating half a cup a day that’s a lot of time turning the oven on and off for four days just to get a few days worth of yogurt for my husband and myself.
Maile wrote: «Curious if anybody has had any success using canned coconut milk?»
I personally have not (2 unsuccessful batches, and no recent re-attempts). I am expecting to try again soon, and also try a completely different non-dairy approach.
However, we have at least one user on the subscription site with a working recipe. This version of it should be visible to non-subscribers:
Daphne’s L-reuteri coconut milk yogurt
Note that it is different than Dr. Davis’ original suggestions.
re: «I used 26 ounces of the coconut milk added a tablespoon of raw sugar 2 tablespoons of Inulin…»
I would suggest, as Daphne does, pasteurizing the mix (without the starter). In addition to controlling any opportunistic microbes in the various ingredients, it will also dissolve any granulated ingredients (such as the sugar you use).
re: «…90 seconds on every 4 hours.»
Have you run the cycle with just water and monitored the temperature?
re: «…that’s a lot of time turning the oven on and off for four days…»
When I was experimenting with using our range for this, I decided that I didn’t want to tie up the appliance for that long, even if it hit temp targets (which it didn’t). A low-power light bulb in a cooler chest is what I use now.
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