For Process Optimization
Sugar and Yeast Performance
In sweet dough systems (e.g. donuts, Danish), yeast is exposed to high concentrations of sugar, creating osmotic stress on yeast cells. To balance the osmotic pressure created by the presence of sugar, yeast releases water, slowing down its metabolism and hence, its fermentative performance. The graph below illustrates the effects of sugar on yeast activity: the greater the sugar concentration, the least CO2 release per minute and the slower the fermentation.
Lean Dough vs. Sweet Dough
Yeast performing well in lean dough have a high ability to metabolize maltose. In lean doughs, sugars like sucrose and fructans are degraded to simple sugars by yeast’s endogenous invertase enzyme. Simple sugars being the yeast’s preferred fuel are degraded within the first hour of fermentation, leaving maltose as the only fermentation substrate.
In sweet doughs, osmotically-resistant Saccharomyces cerevisiae allows for a better fermentative performance. With a low invertase activity, the osmotic pressure is reduced as less sucrose are being converted to simple sugars (e.g. sucrose and glucose).
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