• Question: hey rachel, how does yeast help bread to rise? what is added to self-raising flour to help bread to rise?

    Asked by guitarbanana12 to Rachel on 13 Mar 2013.
    • Photo: Rachel Edwards-Stuart

      Rachel Edwards-Stuart answered on 13 Mar 2013:


      Yeast feeds on sugar (provided by the flour) and produces carbon dioxide. As this gas is produced, it allows the bread to rise. As the yeast grows, each cell grows into two, so you have more yeast cells that are able to produce carbon dioxide. Self raising flour contains sodium bicarbonate. This is known in science as an alkali. When you add it to an acid, it produces carbon dioxide, just like yeast does, but much more quickly. This is why self raising flour will also make bread rise.

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