How to grow sourdough starter for increased production?

I've only baked at home, not commercially, but something sounds amiss if you're throwing away a ton of starter. [And wow, having a multi-lb starter!]

You throw away starter to keep your starter from getting too big, when you're not baking with it. And I'd hope a commercial bakery is always baking with it.

Example: if your starter is 4lbs and you're keeping half (so feeding 1lb flour, 1lb water), then you discard 2lbs, which you promptly replace with the new flour & water. This keeps your starter at 4lbs consistently. Ideally, that 2lbs removed from the starter is what you'd use for your baking (possibly after doubling it, to feed it).

You don't have to remove the 2lbs, either. You can just add 2lbs flour + 2lbs water, doubling your 4lb starter to an 8lb starter.

Completely agree with derobert's answer, though the way to do all of this efficiently is through simple calculation.

You just need to calculate how many feedings between batches of bread and then tailor the amount you save from your previous batch based on that.

For example, the regimen you describe would be appropriate if your bakery requires 26 lbs. of starter for a recipe baked after 3 feedings.

• Day 1: 1 lb. starter, 1 lb. water, 1 lb. flour
• Day 2: 3 lbs. starter, 3 lbs. water, 3 lbs. flour
• Day 3: 9 lbs. starter, 9 lbs. water, 9 lbs. flour
• Day 4: Use 26 lbs. of starter in recipe, leave 1 lb. starter as "Day 1" for next batch and add flour and water to feed

If you think about this a bit, you can derive a general formula for any situation.

For example, assuming you're doing a 1:1:1 starter to water to flour feeding, you should follow these guidelines, depending on the number of feedings you anticipate between batches. Suppose you need amount X (in pounds or grams or whatever) for your recipe.

• 1 feeding: after taking X out for recipe, of the remainder of starter, save 1/2 of X from previous batch as starter for next batch (discard any excess beyond 1/2 of X before feeding)
• 2 feedings: save 1/8 of X from previous batch as starter
• 3 feedings: save 1/26 of X from previous batch as starter
• 4 feedings: save 1/80 of X from previous batch as starter
• n feedings: save 1/(3^n-1) of X

Example: Suppose you need 15 pounds of starter (=X) and will feed twice between batches. In that case, you should start with 1/8 of X = 15/8 = 1.875 pounds. Feed 1.875 pounds of starter with 1.875 lb. water and 1.875 lb. flour, for a total of 5.625 pounds. On next day, feed 5.625 lb. starter with 5.625 lb. water and 5.625 lb. flour for a total of 16.875 pounds of starter. Then you take 15 pounds of needed starter for your recipe, and you're left with 1.875 pounds to begin the process again for the next batch.

In fact, you can use that last formula for a general case of different starter recipes. For example, some people might use a 1:2:2 feeding of starter to water to flour. In that case, you are multiplying the size of your starter by 5 with each feeding, so you'd just put 5 in the denominator of that last fraction instead of 3. If you do a 1:1.5:1.5 feeding, then put 4 (=1+1.5+1.5) instead. In general:

• If you do n feedings which each enlarge starter by factor p, then save a fraction equal to 1/(p^n - 1) of X, where X is the amount needed for each batch

This formula will ensure no wasted starter at all, assuming you have a predictable baking schedule where you always need X amount of starter from every n feedings.

If your baking schedule isn't as predictable, you can always make a slightly larger or smaller batch of starter as necessary.

Some bakers prefer to do different size feedings of starters at different stages of the build. (This is most typical when making "mild" flavored breads using natural yeast, where one of the last stages before the final mix is usually diluted a lot more during feeding to lower acidity.) In that case, the calculation is more complex, but you can still sort it out by working backwards a bit from your final weight of starter for the dough to how much you'd need initially before feedings. In general, there's no need to be producing excess starter that you're not going to use. Many bakers who don't plan to bake again for several days will only save a few ounces of starter (thus feeding and discarding very little) and then gradually build it back up when needed for a large batch.