Wednesday, May 6, 2009

Making Yogurt with a Heating Pad

If you have learned how to make yogurt from my website, then you know that I use a heating pad during the seven-hour yogurt incubation period. I have had more than a few readers ask "why the heating pad?". There are three good reasons I typically respond with:

  1. It is critical that the milk remain at or about 110°F during incubation, in order to ensure propagation of the bacteria that gives us our yogurt. In my experience (through much trial and error), I found that a heating pad keeps the temperature just right, the whole time.

  2. The basic premise of my homemade yogurt website is that you can easily make yogurt in your home with items already on hand, without buying any special equipment.

  3. While I am sure an electric yogurt maker is a nice thing to have, and works just fine, it's one more item in your house that serves no other real purpose when not in use, and takes up counter/cabinet space. In other words, you can't soothe a sore neck with your yogurt maker, like you can with a heating pad!
But a few thoughtful readers have written to me with a few situations that illustrate problems with my reasoning:

  • Some heating pads turn off after a manufacturer's specified length of time. So after three hours or so, it shuts off entirely. This defeats the purpose of using it for steady temperature control. I was unaware of this, since my heating pad does not have such a feature, and can be left on for seven hours without issue.

  • Many people simply don't have a heating pad. I just grew up with one, and figured so did everyone else.

  • Others are uncomfortable leaving it on all night, unattended. I am sure the manufacturer would agree with this position, and I certainly would not want anyone to lose sleep so that they could make some yogurt.
So what are the alternatives? Well, there are a few I am aware of, some good, and some not. Keeping in mind that your goal is to maintain a steady temperature at or near 110°F, consider these:

  1. A warm oven. I have an electric oven, so it is never warm except after having just been used. Then it gets quite cold. Gas ovens, on the other had, have a pilot light, which creates some residual warmth. And depending on your oven's doors seal, it can be rather warm. But probably not 110°F.

  2. A thermos with some hot water bottles (or other heat source) in it. I've never tried this, but it certainly seems plausible. But it would seem to me that the heat is retreating slowly the whole time.

  3. A hotplate. I don't have one of these, and I am not sure how popular they are anymore. But it would seem to be a good bet. Unlike a heating pad, this item was intended to keep a pot warm for hours. And if you entertain a lot, is a useful gadget.

  4. A crockpot. I also do not have one of these, but it would seem the perfect solution for anyone who does. It was designed to hold a steady temperature for hours, and the insert typically comes out for transferring into the refrigerator. If you are a slow-cooking fan, it is probably in use all the time already, and employing it on yogurt making day is no imposition at all.

  5. The YogoTherm Incubator. Like the thermos approach above, I am skeptical that the temperature remains steady for seven hours. But I contacted the manufacturer, and they assured me that it does. They have offered me one wholesale, but I have yet to take them up on it. So while this is one more hunk of plastic around the house, that doesn't do much else, it has its distinct advantages: a) it uses no energy at all, unlike a heating pad or crockpot, b) it doubles as a container to transfer the yogurt to the fridge, and to serve it out of, and c) if taken care of, would presumably last indefinitely. I am definitely going to have to try this, and report back.

So if you have the wrong type of heating pad, don't have one at all, or are worried about leaving it on unattended, I would suggest a crockpot, a hotplate, or the YogoTherm Incubator. All other steps in my tutorial should be followed exactly as written, and you will make consistent homemade yogurt every time out.


  1. This comment has been removed by the author.

  2. I definitely get the feeling that people are a bit antsy about maintaining a perfect temperature over the seven hours.

    Sure, you want to get as consistently close to 110 degrees as possible for the length of the incubation period, but if it dips into the high 90s during that time while you're out at the mall or something, it's not going to spoil or turn out badly -- maybe the bacteria won't grow quite as fast during that time, but it won't be bad at all. Just get it back up to 110 with the heating pad when you return.

    I've made yogurt twice now, once with a heating pad that shuts off (which will be my primary method from now on). As long as it's well insulated, it won't lose heat quickly. I wrap the whole shebang -- my old half-gallon crock from a nonworking crockpot, heating pad underneath -- in a giant beach towel, bungeed to keep it snug. If you need to be away for part of the 6-7 hours incubation time, I recommend being away at the start, when it's going to stay warmest; if you start at 115 degrees, it's still going to be about 95-100 at a minimum a couple hours later if it's well insulated (and probably around 105 if you start with the heating pad on low). When you return you can reset the heating pad and flip it back on every hour or so after it turns off.

    If you absolutely need to be away a lot but want to make yogurt, or if you tend to fret too much over little details (constantly opening the whole thing up and checking the temp, etc.) then perhaps the automated yogurt maker is for you.

  3. I made yogurt yesterday, right after baking bread. I've always used my oven for the yogurt and just turned it on every once in a while to keep it warm, but had a baking stone in there from the bread, so just used IT to keep the oven warm. I did start the yogurt too long after finishing the bread so it had cooled off a bit, but just turned the oven back on for a few minutes, then turned it off and stuck the yogurt in. The stone holds a lot of heat, so kept the oven at a pretty good temperature. 5ish hours later - perfect yogurt!

  4. Silly, silly. Let's get real here. And simple.
    Once the prepared milk, stirred to just below boiling and allowed to cool in a cold water bath 'til a sensitive digit can be immersed fully into it for an uncomfortable count of ten (or for the more conventional, a instant-read thermometer registers 130 degrees Fahrenheit)
    Add one cup of hot milk to your three Tbs of starter (quality plain yogurt, e.g. Brown Cow,
    Continental, Pavel's), blend well, pour bowl into pot and stir.. Cover. Wrap securely in a down comforter or down sleeping bag (I have been doing this for forty-five years now) and set out of a drafty area. NO heating pad, ovens, worries. Eight hours later...perfect yogurt; drain thru dense, thin cloth to chosen consistency and enjoy with fruit or however!
    Simple as that!

  5. Wally,

    You are entitled to your opinion, and if you enjoy the yogurt you make, that's great! But you are straining away a bunch of the healthy bacteria, a big reason why many of us eat yogurt in the first place. Further, you shouldn't have anything to drain, if you keep a consistent temperature during incubation. Unlike when you wrap yourself in a comforter, the pot of milk is not generating heat. It is cooling off the whole time. The comforter slows this, but does not prevent it. A heat source, like a heating pad, does. And after seven hours, the yogurt is thick, not too tart, and there is nothing to drain.

  6. I recently discovered the heating pad method, and it works beautifully. I have a nylon, zipper-top Nalgene bottle insulator. I warm my milk, add my starter, pour into a quart mason jar, slide it into the Nalgene insulator, then wrap that with the heating pad on medium setting. Seven hour later, perfect yogurt. I'm using raw cow's milk and starter made from raw cow's milk yogurt, both from an Amish farmer in PA.

  7. I tried making yogurt this week using a crock pot on "warm" setting. I wrapped my container in a dish towel and inserted in crock pot. Unfortunately the yogurt was steaming when I took it out 7 hrs. later. It turned out thin, so I've used it lilke a Kefir. I bought a heating pad today and a thermometer. Thank you for your tips.

  8. There are many ways to make chili and many ways to make yogurt.
    A few questions:
    1) What is the ratio of milk to yogurt for the starter. From what I have heard it seams like it is about 1 tablespoon per cup of milk. Is that about right. )I know this is not a exact science.)
    2) Incubating temperature: From what I gather its between 105 and 115 Fahrenheit, 110 being ideal. Is that right?
    3) Just how much milk do you put on your corn flakes. Just kidding, just kidding.

  9. Mike,

    I don't make any exact measurements in this regard. But I use 3 Tbs to one half gallon of milk each time I make it. On the 110 degrees, yes that is correct.

  10. Here at a hostel in Colombia, our incubation method is with an old fridge that doesn't work, wrap the pot in a towel, and every few hours put in a pot or two of boiled water. Keeps it nice and warm in there! Have had perfect, delicious, thick yogurt every time!

  11. I have an electric oven which goes down low enough - I know because I used it yesterday after finding everywhere else in the kitchen too cool (I don't have a heating pad. What is a heating pad anyway?).

    My oven goes down below 50C, and I used an oven thermometer to check the temperature - it is accurate. It isn't degree-precise, of course, and it fluctuates as the thermostat goes on and off, but it stays between 30C and 50C and seems to give good results.

    The yoghurt seemed whey-y when it came out, but I stirred and chilled it and in the morning it had a great texture.

    Being able to leave it unattended is important for me as I want to make it overnight.

    Of course, it's summer, and I live in a temperate climate, so the heating is off but the air temperature is generally below 20C. In winter when the heating is on, I hope to be able to make yoghurt on the same high shelf I use for proving bread dough.

  12. On the subject of slow cookers, some brands may be able to do this on "keep warm", but not the Crock Pots - the current models run very hot. The fuller you fill it, the cooler it gets, but I don't think it will ever run cool enough to culture. I think you'd need a thermostatic slow cooker for that.

    However, there is a technique for using the Crock Pot to make yoghurt - check out

    It involves using the crock to heat the milk and then allowing it to cool, adding the starter and wrapping the whole thing in towels to culture in the residual warmth. Because of the heavy crock and the metal jacket, they do stay warm for a very long time.

    The milk-heating and cooling take a shockingly long time (which is why I don't fancy it), but it will hold the milk at a good temperature for a long time without boiling it.

  13. For those of you who have a food dehydrator, it works great as a yogurt incubator. I expect that, of those interested in yogurt making, a good number are also interested in or already do food dehydrating - so the equipment may already be in their self-sufficiency arsenal. My Excalibur food dehydrator even came with instructions as to how best to use it to make yogurt. Give it a try!

  14. I'm planning on using an electric blanket. Those are designed to maintain a steady temp for 10 hours before shutting off. Plus, the darn heating pad went missing again.

  15. To disable the timer on your heating pad. Check out this link!
    Worked like a charm for me and I don't even have the same brand as this guy.

  16. Thanks for taking the time to discuss this, I feel strongly about it and love learning more on this topic. If possible, as you gain expertise, would you mind updating your blog with more information? It is extremely helpful for me.

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