Yeast is used as a leavening agent in bread making. The yeast metabolizes with the natural carbohydrates in the flour, converting them to CO2 and ethyl alcohol and it is the CO2 gas that raises the bread. So, when making yeast bread it is very important that the mixture not be overheated during the leavening process because if it is overheated the bread will not raise. Explain in terms of protein denaturation.