The yeast is a living creature that feeds on the starch from the flour and releases the gases from this reaction in large quantity. They also release small quantities of other molecules from their other biosynthetic processes. Some of these release as the odorants we smell and associate with yeast. The malty smelling odorants methylpropanal plus 2 and 3-methylbutanol are major odorants we think of a with yeast. The roasty smelling 2-acetyl-1-pyrroline molecules have a large impact in the final bread scent. 1-octen-3-one and (E)-2-nonenal combine together and are responsible for fatty notes to the scent.
Different strains of yeast release different ratios of odorants and flavorants. This is why a strong sour dough yeast culture is a prized possession.
Answers & Comments
Verified answer
The yeast is a living creature that feeds on the starch from the flour and releases the gases from this reaction in large quantity. They also release small quantities of other molecules from their other biosynthetic processes. Some of these release as the odorants we smell and associate with yeast. The malty smelling odorants methylpropanal plus 2 and 3-methylbutanol are major odorants we think of a with yeast. The roasty smelling 2-acetyl-1-pyrroline molecules have a large impact in the final bread scent. 1-octen-3-one and (E)-2-nonenal combine together and are responsible for fatty notes to the scent.
Different strains of yeast release different ratios of odorants and flavorants. This is why a strong sour dough yeast culture is a prized possession.
Yes, since CO2 is being released, it causes the bubbles in the bread. What we smell when bread is baking is called ethyl alcohol.