Fructose can be used as a substrate in yeast fermentation.
The Correct Answer and Explanation is :
Yes, fructose can be used as a substrate in yeast fermentation.
Explanation (300 words)
Fructose is a monosaccharide that serves as a readily available source of carbon for yeast fermentation. Yeasts, particularly Saccharomyces cerevisiae, metabolize sugars like fructose through glycolysis, a process that breaks down sugar molecules to generate energy in the form of adenosine triphosphate (ATP) and byproducts such as ethanol and carbon dioxide.
Fructose is transported into yeast cells via specific sugar transporters in the cell membrane. Once inside, it is phosphorylated to fructose-6-phosphate by the enzyme hexokinase. Fructose-6-phosphate then enters the glycolytic pathway, where it is converted into pyruvate. Pyruvate undergoes decarboxylation to produce acetaldehyde, which is subsequently reduced to ethanol during alcoholic fermentation under anaerobic conditions.
Fructose is often present in natural substrates used in fermentation, such as fruits and honey, where it coexists with glucose and sucrose. Yeast can utilize fructose as effectively as glucose, although some yeast strains exhibit a preference for glucose when both sugars are available. This preference, known as glucose repression or the Crabtree effect, occurs because glucose is metabolized more efficiently due to its direct entry into the glycolytic pathway without requiring additional enzymatic steps.
In the context of industrial applications, fructose is valuable in fermentation processes for brewing, winemaking, and bioethanol production. For example, during wine fermentation, fructose and glucose are the primary sugars in grape juice. Yeast ferments both sugars to produce alcohol, contributing to the wine’s flavor profile.
It is important to note that variations in yeast strain and environmental conditions, such as temperature and pH, can influence the efficiency of fructose utilization. Overall, fructose is an effective substrate for yeast fermentation, enabling various commercial and biochemical processes.