Abstract
β-glucan extraction from spent brewer’s yeast is a long process that starts with the lysis of yeast cells, this step lasting up to 36 h and can be disadvantageous when working on a small scale. In this study, a rapid cell rupture method was selected for the lysis of spent brewer’s yeast to obtain β-glucans. Optimal parameters were determined for the lysis of a cellular suspension of spent brewer’s yeast by vortexing with glass beads. Thus, parameters such as the number of 10 min vortex cycles from 1 to 3, the concentration of cell suspension (5, 10, and 15%), and the ratio of yeast/glass beads (1:1, 1:2, and 1:3) were varied in a Box-Behnken design. A cell lysis mechanism using glass beads allows the cell to rupture and permits the removal of intracellular content. An increase in yeast suspension concentration decreased the disruption efficiency, while a proportional increase was observed with the yeast/glass beads ratio and the increasing number of vortexing cycles. The optimal parameters for cell lysis were found to be a cell suspension concentration of 5%, a ratio of yeast/glass beads of 1:2, and a vortexing cycle of 3, with a disruption efficiency of 99.8%. The β-glucan fraction extracted from the optimal sample showed characteristic absorption bands at 1370.77 and 1153.92 cm−1, the content of β-glucan being 78.53%.
Highlights
The beer production industry generates large amounts of valuable by-products with many biological and functional values
Spent brewer’s yeast is such by-product that could be used as raw material for β-glucan extraction since the most important polysaccharides found in cell walls are glucan and mannan with linear bonds at β-(1-3)/(1-6), the most frequent being the β-(1-3) [1]
For total protein extraction, improved methods, such as the one described by Zhang et al (2011) using lithium acetate (LiAc) in combination with NaOH, which enhances the permeability of yeast cell walls, releasing proteins from cells, could be used [2]
Summary
The beer production industry generates large amounts of valuable by-products with many biological and functional values. Spent brewer’s yeast is such by-product that could be used as raw material for β-glucan extraction since the most important polysaccharides found in cell walls are glucan and mannan with linear bonds at β-(1-3)/(1-6), the most frequent being the β-(1-3) [1]. There are various methods of cell lysis that can be implemented for yeast extraction, depending on the cellular components that should be isolated. For lipid extraction, the homogenization of a cell suspension in the presence of organic solvents and glass beads with a diameter of 0.25–0.30 mm can be effective, according to the data presented by Schneiter and Daum (2006) [3]. The authors showed that the method allows cell disruption over four cycles of 30 s at 1700 rpm with a pause of 30 s between cycles
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