In the present assignment we are to answer the question on whether yeast needs air to make bread rise. First off, we need to come up with a hypothesis, and we believe that it does for it is a metabolism process which may not take place without air. Now let us see whether we are right in our assumption or not.
Actually, we are and that is why. It is well known that yeast brings about fermentation processes - we ourselves have proven it experimentally. Yeast takes part in this fermentation process due to its interaction with such components as sugar and as a result it excretes carbon dioxide – so it does need carbon dioxide which is an essential part of air and yeast itself excretes this gas. (Arthur, 1976)
Fermentation plays, in fact, an important role in cooking as it strengthens and develops gluten in dough, making it more fragrant and tasty. But how exactly does fermentation happen? As soon as yeast interacts with sugar, flour, water and dough, yeast enzymes break down starch molecules into sugar – that is where sugar produced! After that a liquid is exuded that ion its part releases carbon dioxide in the dough.
Just as in case of kneading, we owe yeast very much in its ‘work’ on developing gluten. By means of carbon dioxide bursts which are released into air bubbles, molecules of protein and water connect with each other thus creating more gluten. And it is at this stage that the dough starts rising, with gluten being strong and smooth and fragrant.
References
Arthur, H. (1976) Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts. Journal of Bacteriology 128 (1): 56–68.
Sandhu D.K. (1985). "Yeasts associated with pollinating bees and flower nectar". Microbial Ecology 11 (1): 51–58.
