Monday, April 23, 2007

Herbert: A Pet In A Jar

Mad-kitchen-science, or biology is delicious.

We keep a yeast colony in a large lidless glass jar in our kitchen. His name is Herbert, because it seems like a good name for a pet in a jar. "He" is covered with a red-and-white napkin tied, bandanna-style, over the mouth of the jar. I take some out and feed him about once a week, more often in hot weather if he's not refrigerated.

The flavor is really good, a lot like a good San Francisco sourdough, and it seems to have a lot to do with how I feed him.

Here's my method for making your own sourdough, with a good west-of-the-rockies flavor.

Making Herbert

Preparation and utensils:
Get a large glass jar, a 1.5 litre or 2 quart size, in tempered glass (so sterilizing it isn't a cause for high blood pressure), and a clean square of close-weave cloth, large enough to tie around the mouth of the jar easily. Wash, rinse thoroughly, then boil the cloth and allow to dry (in the drier on HOT is good). Sterilize the jar with boiling water, by pouring boiling water into it after filling with warm, then hot tap water, or by immersing in a canning kettle (if you have one). Also sterilize any utensils you will use - measuring cups and spoons, plastic chopstick(or spoon or whisk), and wash your hands well.

Science note! Use only glass, plastic or wood utensils for wet ingredients, as metal utensils can affect the pH of the yeast mixture in some way. Stainless isn't as bad as, say, iron or copper, but stainless isn't really stainless - it's resistant, and if its coating of oxidation-resistant molecules is damaged (by scratching, for example), iron oxides can get into your mixture and affect the yeast.

Wood safety: I you use a wood spoon, get anew one. Always scald the wood before use, if you choose to use one, and keep it ONLY for use with your sourdough. I have not found that using wood is really better than plastic in this regard, so It's much more of a hassle than it's worth.

Once everything is ready, you can start.

Prepare a boosted sourdough starter in the jar:
Take equal parts (about a cup, by volume, but you can use a little more or less, or even double it) of the following:
  • water - boil and then cool to lukewarm
  • milk - scald (heat just until small bubbles form, do not boil) and cool until lukewarm
  • flour - Unbleached all-purpose white flour, or white bread flour

Place these in the jar together, and mix until creamy with only few lumps. Next add:
  • 1 packet OR 1 scant tablespoon of instant yeast

Stir the yeast in gently, cover with the cloth, tying it tightly. Set your starter aside for several hours or a couple of days. How long depends on the ambient temperature and humidity in your kitchen. 65 to 75 degrees Fahrenheit, with 35% to 40% humidity is just about right. Cooler, it takes longer, and drier, it can also take a little longer. Yeast likes warmth and moisture, just like we do.

Watch the activity level - after your pet yeast colony has foamed up and subsided (may take a few hours or up to a day), you need to add some more food to keep it going during the initial colony formation period. Add one of the following at a time, stir, cover and wait for the foam/collapse cycle to complete (each time will take a little longer until the colony is well established).
  • A rough handful of potato flakes OR a small boiled, peeled and mashed potato
  • A rough handful of rice baby cereal OR 1/2 cup pureed cooked rice OR 3 TBSP of rice flour
  • 1 Tbsp sugar (any kind - whatever you use in everyday cooking)
  • A rough handful of flour
Each time you feed your incipient colony during this first week or so, add a different food. You can follow the list in sequence if you like. This develops the complex flavor of a good sourdough. If it seems a little thick, add a little water until it's about the consistency of sour cream.
Science note! The reason we add several different starch types (and a sugar) to our developing colony is because the starches are metabolized to produce slightly different flavors by our yeasts. The starches taste slightly different to us, but the yeasts make those differences more apparent. Rice, potato and other starches are used to create different flavor complexes by bakers for this reason.

After your sourdough has developed a good flavor, you can keep it semi-dormant in the fridge. You can check the flavor by smelling the colony - it ought to smell like a good sourdough loaf, with a good sharp tang and a few deeper notes created by the mixture of starches used to make it.

Go on, give it a name. I'm all for naming your yeast colony.

Maintaining Herbert

Feed once a week if you will be keeping it dormant, using a mixture of 2tbsp flour, 1 tsp sugar, 2tbsp water alternated with an equivalent amount of rice or potato starch and water.

To use, take it out of the fridge and set it on the counter overnight, and feed it if looks a little low. To activate your yeast, or keep it fed if you are using it regularly, feed it a combination of equal parts flour, potato starch, and rice starch (add a little sugar if you need it to start a little faster), mixed with water, milk (not too often), or whey (I use whey I set aside after making cheese at home). Use for baking, making pancakes, lots of stuff. Sometimes, when I don't want to wait for a sourdough loaf, I'll add a cup to a regular recipe just for the flavors.

Every once in a while, when the jar gets a bit crusty around the top ( I do this every 2 months), transfer the sourdough to a clean temporary container ( I use a large mixing bowl/measuring cup), cover with a clean cloth, then clean and sterilize the jar and the cloth cover. We refer to this as "Herbert's Bath Day" around here.

If your colony gets too big and you aren't interested in baking that day, make pancakes.

Recipes for using your starter:

Sourdough science:

Next Installments: Pancakes! and a couple of modernized genuine-antique bread recipes for using your colony.


  1. I <3 sourdough!! Thanks for the recipe and great tips. I had now idea metal could affect the yeast mixture. Maybe that's one of the many reasons my dough hardly rises.

  2. Its always cute to see someone name their starter :)


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