The Science of Bread

January 21, 2007 @ 1:27 pm | Filed under: ,

Hmm, the high educational value of this topic might make it a good post for Lilting House.

Jane and I are exploring the science behind the loaves we’re baking. Found this fun site: The Science of Cooking. An excerpt from the sourdough page:

In addition to flour, water, and yeast, your starter also contains bacteria. When these bacteria feed on the sugars in flour, they produce acidic by-products. This is what gives sourdoughits sour taste.

Actually, all doughs contain at least some bacteria. So why aren’t all breads sour? In doughs made with bakers’ yeast (the kind you buy in the store), the yeast outnumber the bacteria. Since both compete for the same sugars, the yeast win out, and the bacteria don’t have a chance to produce their acidic by-products. In sourdough, yeast and bacteria are more closely balanced, so the bacteria have a chance to add their flavors to the bread.

Sourdoughs and other raised breads also differ from one another because of the eating habits of the yeasts that make them rise. The predominant yeast in sourdough, Saccharomyces exiguus, cannot metabolize maltose, one of the sugars present in flour. Baker’s yeast, on the other hand, has no trouble feeding on this sugar. Since the bacteria that give sourdough its taste need maltose to live, they do much better in the company of sourdough’s yeast because they don’t have to compete for this sugar.

Other links:

Wikipedia on sourdough

How Stuff Works on sourdough

The history & microbiology of sourdough:

Sourdough culture is a yeast living symbiotically with a friendly
lacto-bacteria. We need to start with enough of the right organisms so
that they can become the dominant culture, food and water and the right

Given the right organisms, the optimum temperature is just
over 80F/27C. Much hotter and the activity of the yeast declines. Above
95F/35C the yeast is effectively dormant or dead. The bacterial
activity peaks at 93F/34C, so some bakers choose to ferment at 90F/32C
to get a sourer bread. At 70F/21C the activity of the yeast has roughly
halved, so the fermentation will take twice as long.


    Related Posts


5 Reponses | Comments Feed
  1. Lorraine says:

    Lissa! I’m so excited about this blog! Baking bread as well as knitting socks are my passions! I even had an outdoor woodburning bread oven built in our Vermont house! It has sort of turned into a pizza oven, but I still love making the pizza dough. I tried sourdough a few times. once with a starter I purchased and once I tried to make my own starter out of a bottle of beer some flour and a long sit on the counter. Both were great but I didn’t feed the starters to keep them up and they eventually failed. This little blog will be a nice new inspiration to get into my bread baking again. Funny side story…when I gave it all up for a while I received a bread machine for Christmas….I guess it was a hint that my bread was missed 🙂

  2. Busby SEO Challenge says:

    great move
    nice site

  3. Busby SEO Challenge says:

    cool blog
    ket it up
    Busby SEO Challenge

  4. kabonfootprint says:

    good job..
    nice blog

  5. Kathleen says:

    Congratulations on an inspirational website! I love all the details about your starter, and the science behind it helps to understand the whole process. All the best with future breadmaking, for both you and your kids!