I made two batches of yogurt, one using a cooler and another one using sous vide. As a starter, I used yogotherm cultures. All the milk was heated and cooled to the same temperature, at the same time, in the same pot (82C and then 42C). The sous vide was set to 42C and the yogurt in the cooler had some towels and hot water bottles around it, and was placed near the fire place. I let both batches of yogurt stay at this temperature for the same amount of time (7 hours or so). The result was interesting... both batches came out with similar consistency, but the sous vide yogurt was *a lot* more sour than the cooler one. The only difference between the two batches was really the temperature at which they were held. Sadly, we enjoyed the cooler yogurt much more. I want to like sous vide for making yogurt. I am hoping that once I figure out the ideal temperature and time for our taste, I'll be able to reproduce the results easily (which is a problem I have with the cooler method). I want to make another batch based on a good plan, but I'm a bit unsure about what to try next. Here's what I'm thinking of trying: * Reduce the amount of time that I keep the yogurt at the target temperature. I'm assuming that the same enzymes that happily reproduce at warm temperatures also cause sourness, so maybe cutting down on the time will produce less sourness. I'm not so sure this will work because the Modernist Cuisine says to hold the temperature for 8 hours, and I already reduced it to 7 on my first try. Will the yogurt set if I reduce the time further? * Increase the sous vide temperature to 45C. The Modernist Cuisine says to incubate at 45C - I set it to 42C by mistake. However, some online article that I can no longer find had the temperature range in which yogurt can be made successfully, and both temperatures are within that range. So I'm not so sure that this will make a big difference. Any information that anyone can share is very welcome! Thanks in advance!
