DAlessandro-000869-0016.pdf - PE 2 C 3 E:5 A 5 EV 4 TOTAL 19/24 Internal Assessment-IB SL BIOLOGY Title Effects of temperature on sourdough fermentation

DAlessandro-000869-0016.pdf - PE 2 C 3 E:5 A 5 EV 4 TOTAL...

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1 Internal Assessment-IB SL BIOLOGY Title: Effects of temperature on sourdough fermentation. Research question: Is there any significant change on the height in cm of a fermented sourdough at different temperatures (-7ºC, 5ºC, 25ºC, and 62ºC)? Aim: To find out if the fermentation of sourdough measured in cm is affected by different temperatures (-7ºC, 5ºC, 25ºC and 62ºC). Background info with research and hypothesis: Sourdough is a dough used for making different kinds of bread. Its difference with the normal bread dough is that yeast is not added, and flour needs to be organic in order to have the whole grain, which still, contains the yeast. Sourdough is basically a mixture of flour and water fermented during several days. (Christensen, 2015) In bread production alcoholic fermentation takes place in the breaking down of glucose into carbon dioxide and ethanol. Sourdough is able to ferment, and elevate, only using whole grain flours, because white flours are grinded, making the grain loose the yeast it contains. The yeast, Saccharomyces cerevisiae , inside the whole grain is strongly cultured, and the bacteria Lactobacillus sp. grows beside. This bacterium species, along with the sugars found in the flour, release as a product carbon dioxide and ethanol, making the sourdough elevate and the ethanol evaporate when cooked. Sourdough bread can a few times have a sour flavour due to this bacterium that produces lactic acid. Commercial bread does not contain Lactobacillus sp. , therefore, the mild sour taste is avoided. (Christensen, 2015) There is not only a difference in preparation, but a difference in the way our body digests industrialized bread and sourdough bread, that is one of the main reasons sourdough PE: 2 C: 3 E:5 A: 5 EV: 4 TOTAL: 19/24
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