Effect of varying starch properties and mashing conditions on wort sugar profiles

Abstract

The aim of this research was to investigate the relationship between starch composition in barley and its malted counterpart alongside malt enzyme activity and determine how these factors contribute to the fermentable sugar profile of wort. Two Australian malting barley varieties, Commander and Gairdner, were sourced from eight growing locations alongside a commercial sample of each. For barley and malt, total starch and gelatinisation temperature were taken, and for malt, αand β-amylase activities were measured. Samples were mashed using two mashing profiles (infusion and Congress) and the subsequent wort sugar composition and other quality measures (colour, original gravity, soluble nitrogen) were tested. Variety had no significant (<0.05) effect on any barley, malt, enzyme or wort characteristics. However, growing location impacted gelatinisation temperature, colour, malt protein content and original gravity. The gelatinisation temperature in malt samples was higher, by~0.8°C, than in the equivalent barley sample. Several malt samples, even with protein contents <12.0%, had gelatinisation temperature >65°C. The fermentable sugars measured in the malt prior to mashing showed a higher proportion of maltose than glucose or maltotriose. In addition, there were significant differences in the amount of sugar produced by each mashing method with the high temperature infusion producing a higher amount of sugar and proportionally more maltose. There is scope for further research on the effect of genetics and growing environment on gelatinisation temperature, mash performance and fermentable sugar development. Routinely measuring gelatinisation temperature and providing this information on malt specification sheets could help brewers optimise performance.

Constant temperature mashing at 72 °C for the production of beers with a reduced alcohol content in micro brewing systems

“…In the case of isothermal mashing the concentrations hardly vary after 60 min whereas in the case of conventional mashing there was an almost continuous increase from 40 to 80 min (thus in the regime of the 62 °C rest) and a further increase in the regime of the 72 °C rest. Furthermore, the total concentration of maltose + maltotriose was higher in the case of conventional mashing at the end of the procedure, as was already demonstrated by Fox et al [33].…”

Effects of genotype and environment on productivity and quality in Californian malting barley

“…In preparation for an analysis of starch gelatinization, the grain samples were ground in a Disc Mill (Buhler DLFU, Buhler AG, CH‐Uzwil) using the fine (0.2 mm particle size) setting into barley flour. Differential scanning calorimetry was then conducted using a modified procedure described previously (Fox et al., 2019). Briefly, 2 mg (±0.15 mg) of barley flour was weighed into a Tzero aluminum pan (TA Instruments), to which deionized water was added until the total mass was 5 mg (±0.15 mg).…”

A continuous mashing system controlled by mean residence time

“…Gelatinisation of mash is an important precondition for the starch degradation (Brandam et al, 2003). Fox et al (2019) reported typical onset gelatinisation temperatures for malt in a range of 54.2 to 60.5°C and for barley in a range between 56.6 to 62.0°C. It is noteworthy that Evans and Fox (2017) found that β-amylase activity during long resting times can be increased by mash temperatures between 45 to 55°C compared to the mashing process without a protein rest.…”