In what order are fermentable sugars consumed by yeast?

The consumption of fermentable sugars by yeast follows a specific order based on the yeast's ability to utilize different types of sugars efficiently. Yeast primarily uses glucose first because it is a monosaccharide and is readily absorbed and metabolized by the yeast cells. This simple sugar requires minimal energy for transport into the cell and can be quickly converted into energy, making it the preferred choice for the yeast during fermentation.

Following glucose, yeast typically metabolizes maltotriose, which is a trisaccharide made up of three glucose molecules linked together. Maltotriose is more complex than glucose and requires specific enzymes, such as maltase and glucoamylase, for degradation before it can be utilized. The yeast's enzymatic machinery allows it to break down maltotriose after the simpler glucose has already been utilized.

This order is significant in brewing and fermentation processes because the presence and concentration of these sugars can impact the rate of fermentation and the final characteristics of the beer or other fermented products. Understanding this sequence helps brewers and fermenters optimize their processes to achieve desired flavors and characteristics in their final products.