Cooking challanges
Sometimes I really feel like I bring my work home in the form of cooking. Which is not to say that I'm cooking viruses on my stove. It's more that I've got a sourdough starter in the fridge, and I've been making yogurt. These are very similar to, if not exactly like, cell culture. You have to feed them, split them so they don't get too crowded, maintain the right temperature.
The starter and I go back and forth on how I feel about it. (Bread made with only starter? Three days of rising later it's still a brick.) But with a little extra yeast it's quite tasty.
The yogurt has been much more reliable. Here's my protocol:
Heat 4c milk to 185F (medium heat, medium saucepan) as measured by instant-read/probe thermometer.
Cool milk to 115F. Stir in ~1/3c live culture yogurt. Move to slightly-larger-than-quart glass jar. (Make a gigantic mess.) Put jar in a metal wine cooler lined with an electric heating pad (tea towel between hot pad and jar) turned to high. Cover with additional tea towel, let sit 6-12 hrs, keeping temp around 110F.
And it always works. Except the last two times.
Time A I used my new probe thermometer with the old probe from the last thermometer. Temps all looked good, and I left the probe in while it cultured (something I used to do all the time with this same probe), but it set up oddly, very stretchy and rubbery, but not firm. It drained very slowly. I turned it into spinach dip. (That was fine.) This included some whole milk, rather than all 1%
Time B I used the same thermometer, and the same starter yogurt ~one week later. This time I couldn't find the glass jar (it's hiding), so I used a Nalgene that I have used for this before. I washed it thoroughly since it hadn't been used in forever. I started the incubation on Friday night, and when I tried to drain it on Saturday morning it hadn't set up at all. It was practically still milk, and when it did eventually drain the drained liquid wasn't clear-ish yellow, but rather looked like milk. The little bit that had thickened was rubbery to the point of pizza cheese.
So I'm confused. Here are my thoughts about what went wrong.
1. My starter yogurt was going bad or the bacteria populations had changed.
2. The old probe doesn't work with the new thermometer, and is giving me bad readings, either too cool (and I'm killing the bacteria) or too warm (and it's too cold to grow).
3. The presence of the metal probe interferes with the growth of the bacteria. I think this is unlikely, as the setup is based on the one described in Good Eats, and I know that it has worked before.
4. The Nalgene did terrible things. Dunno.
So here's my plan for the next go:
1. Start with new store-bought yogurt (with live cultures, obviously).
2. Use the probe that is supposed to come with the thermometer, and check it during heating, cooling and incubating, with my other 2 instant-read thermometers. Leave it out during incubation.
3. Find the jar and run it through the dishwasher before use.
Does anyone have any insight?
The starter and I go back and forth on how I feel about it. (Bread made with only starter? Three days of rising later it's still a brick.) But with a little extra yeast it's quite tasty.
The yogurt has been much more reliable. Here's my protocol:
Heat 4c milk to 185F (medium heat, medium saucepan) as measured by instant-read/probe thermometer.
Cool milk to 115F. Stir in ~1/3c live culture yogurt. Move to slightly-larger-than-quart glass jar. (Make a gigantic mess.) Put jar in a metal wine cooler lined with an electric heating pad (tea towel between hot pad and jar) turned to high. Cover with additional tea towel, let sit 6-12 hrs, keeping temp around 110F.
And it always works. Except the last two times.
Time A I used my new probe thermometer with the old probe from the last thermometer. Temps all looked good, and I left the probe in while it cultured (something I used to do all the time with this same probe), but it set up oddly, very stretchy and rubbery, but not firm. It drained very slowly. I turned it into spinach dip. (That was fine.) This included some whole milk, rather than all 1%
Time B I used the same thermometer, and the same starter yogurt ~one week later. This time I couldn't find the glass jar (it's hiding), so I used a Nalgene that I have used for this before. I washed it thoroughly since it hadn't been used in forever. I started the incubation on Friday night, and when I tried to drain it on Saturday morning it hadn't set up at all. It was practically still milk, and when it did eventually drain the drained liquid wasn't clear-ish yellow, but rather looked like milk. The little bit that had thickened was rubbery to the point of pizza cheese.
So I'm confused. Here are my thoughts about what went wrong.
1. My starter yogurt was going bad or the bacteria populations had changed.
2. The old probe doesn't work with the new thermometer, and is giving me bad readings, either too cool (and I'm killing the bacteria) or too warm (and it's too cold to grow).
3. The presence of the metal probe interferes with the growth of the bacteria. I think this is unlikely, as the setup is based on the one described in Good Eats, and I know that it has worked before.
4. The Nalgene did terrible things. Dunno.
So here's my plan for the next go:
1. Start with new store-bought yogurt (with live cultures, obviously).
2. Use the probe that is supposed to come with the thermometer, and check it during heating, cooling and incubating, with my other 2 instant-read thermometers. Leave it out during incubation.
3. Find the jar and run it through the dishwasher before use.
Does anyone have any insight?