Comparison of assimilation of fermentable sugars in wort by the immobilized yeast in alginate gel and the free yeast in high gravity brewing

Anh Kim Hoang,Hien Quoc Tran,Man Van Viet Le

doi:10.32508/stdj.v16i3.1614

Anh Kim Hoang, Hien Quoc Tran + Show 1 more

Open Access

https://doi.org/10.32508/stdj.v16i3.1614

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Abstract

In this work, the assimilation of different fermentable sugars by the immobilized yeast in alginate gel and the free yeast under high gravity brewing conditions was investigated and compared. Both immobilized and free yeast utilized glucose, fructose, sucrose and maltose in wort from the beginning of the fermentation. Maltotriose uptake of the fixed cells was also observed during the first hours of fermentation while the free cells only started assimilating maltotriose after the first 48 h. High osmotic pressure at the start of the fermentation changed cellular morphology and that could decelerate the maltotriose uptake of the free yeast.

Highlights

Wort contains different sugars, including fructose, glucose, sucrose, maltose and maltotriose as well as other carbohydrates, in varying concentrations [2,7]
The kinetics of sugar assimilation of the immobilized yeast in alginate gel and the free yeast are presented in Figure 1 and 2, respectively
Patel et al suggested that sucrose hydrolyzed into glucose and fructose by the enzyme invertase on the cytoplasmic membrane of yeast and the yeast assimilated the substrates [5]

Summary

Introduction

Wort contains different sugars, including fructose, glucose, sucrose, maltose and maltotriose as well as other carbohydrates, in varying concentrations [2,7]. The utilization of wort carbohydrates, especially the utilization of maltose, glucose and fructose by the yeast is a major determinant of fermentation efficiency and final beer quality. According to Boulton et al, sucrose was utilized first and the resultant hydrolysis causes a transient increase in the concentration of fructose. Completion of assimilation of glucose was followed by utilization of maltose, the major wort sugar. According to D’Amore et al, when glucose and fructose are fermented separately, both sugars are utilized at similar rates. When fermentations are conducted in media containing an equal concentration of glucose and fructose, glucose is utilized at approximately twice the rate of fructose.

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