The influence of proteolytic and cytolytic enzymes on starch degradation during mashing

Abstract

The objective of this research was to investigate the impact of proteolysis and cytolysis on starch degradation over the course of the mashing process. A proteolytic enzyme (Neutrase 0.8L, Novozymes) and a number of cytolytic enzymes (barley β-glucanase from Megazyme, Shearzyme 500L and Ultraflo Max from Novozymes) were used to test their efficiency on starch degradation during mashing. The proteolytic and cytolytic enzymes had positive effects on the levels of starch-degrading enzymes and starch solubilization during mashing, resulting in higher levels of wort sugar compared with the control, indicating that proteins and residual non-starchy polysaccharides limited the digestibility of starch during mashing. Moreover, the proteolytic enzyme showed a significantly greater improvement than the cytolytic enzymes, yielding a 57% increase in β-amylase, a 173% increase in limit dextrinase, rapid starch solubilization during mashing and a higher percentage of fermentable sugars in resultant wort. The increases in limit dextrinase and β-amylase promoted by the protease suggest that sufficient proteinaceous inhibitor existed in the wort during mashing to inhibit their activities, leading to the unavailability of β-amylase and especially limiting dextrinase. Furthermore, Ultraflo Max, which contained a β-glucanase-xylanase mixture, showed a greater improvement than either the individual β-glucanase or the xylanase on starch hydrolysis. These findings suggest that β-glucanase is the major enzyme responsible for the degradation of cell walls, and that the complete hydrolysis of the residual cell walls depends on the synergistic effect of β-glucanase and xylanase. The results suggest that brewers should adjust the degradation of the cell walls and correct the degree of protein modification in order to obtain the desired wort composition.

Posttranslational Modifications Drive Protein Stability to Control the Dynamic Beer Brewing Proteome

“…␤-amylase followed a similar trajectory but at consistently lower abundance. The temporal changes in the levels of these proteins we observed here is therefore consistent with the temperature-dependent enzyme activities (26,27), consistent with soluble enzyme abundance driving overall amylase activity in wort.…”

“…␣and ␤-amylase are critical for the hydrolysis of starch into fermentable sugars by cleaving starch at internal ␣(1, 4) linkages and at nonreducing ends, respectively (1,3,25). The activities of these enzymes in situ during the mash have been reported to peak at 63°C for both ␣ and ␤-amylase and decline above 70°C for ␣-amylase and at 65°C for ␤-amylase (26,27). Our proteomic analysis showed that ␣and ␤-amylase initially had similar levels in the mash ( 2C).…”

“…␣-amylase cleaves internal ␣(1-4) glucosidic bonds in starch, while ␤-amylase releases maltose disaccharides from the nonreducing ends of starch polymers or maltooligosaccharides (1,3,25). Maintaining high ␣and ␤-amylase activity is made difficult by the low unfolding temperature of ␤-amylase relative to ␣-amylase (3,26,27). It is generally accepted that a mash temperature of ϳ65°C is appropriate to keep both enzymes stable while allowing efficient conversion of starch to oligomaltose but high enough to allow adequate gelatinization of starch (1,3).…”

Effect of Maize as Adjunct and the Mashing Proteolytic Step on the Brewer Wort Composition

“…The proteolytic step promotes the hydrolysis of proteins that involve the starch fraction, increasing its exposure for enzymatic action. This proposition is further confirmed by the results obtained by Hu and collaborators [31], who show that proteolysis has a great impact on the degradation of starch, including the sugar content of the resulting wort. Table 3 shows the positive effects for the proteolytic step on the TRS content.…”

Aqueous and enzyme-extracted phenolic compounds from brewers' spent grain (BSG): Assessment of their antioxidant potential

“…Depol 740L is a feruloyl esterase which has been shown to be effective in the release of bound ferulic and p‐coumaric acid (Forssell et al, ). Shearzyme 500L is a xylanase and Ultraflo Max is a β‐glucanase–xylanase mixture (Hu et al, ). Extracts were prepared from wet (75% moisture) and dry samples (11% moisture) of both pale and black BSG.…”