|MadSci Network: General Biology|
Hi Lyn, The answer depends on what you mean by "fresh". Bread usually goes bad either by staling, which involves the starch in the bread, or by spoilage from microorganisms like molds. The yeast is added to bread dough because it produces carbon dioxide, which forms bubbles in the stretchy wheat proteins in the bread dough, making the dough rise and giving desired "loaf volume". The yeast also adds aroma and flavor to the bread. In commercial production, yeast can be one of the most expensive ingredients to use, so a lot of research involves looking at ways to make good bread with less yeast. Preservatives are added to both prevent microbial spoilage and staling. Interestingly, some yeast strains may produce "natural preservatives", which aren't all that different from "artificial preservatives". By increasing the yeast concentration in your bread, you may get some preservative effect due to byproducts of the yeast metabolism. However, you may also get a lot more carbon dioxide, which could over expand your bread dough. A couple of limiting factors will be the amount of food (sugar) for the yeast and the amount of time that the dough is allowed to rise. So, do some mad scientist experimentation and try it. At least now, you might have some idea of what is happening either way it turns out. I hope this helped.
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