The suitability of sorghum, millet and barley varieties for producing brewers malt.

摘要

The purpose of this study was to evaluate the use of non-traditional cereals for making brewers malt. Twenty two grain varieties were evaluated which included USA millets, Kenyan millets, Kenyan sorghums, Kenyan standard barleys and a USA barley. The twenty two grains were germinated at 14, 18 or 22°C for 2, 4 or 6 days. Malts were made from each treatment (198 total) and analysis of traditional grain and malt properties were completed. Additionally, analyses included polyphenols and tannins content, fermentability evaluation, diastatic power, alpha amylase enzymatic determination, and the fructose, glucose, sucrose and maltose sugars content.;The results indicated that all grains were acceptable for producing brewers malt. The production of malt from the millets and sorghum groups had a comparable total malting loss to barley at 10.17, 13.82, and 12.43% dry matter for barley, millet and sorghum respectively. Malt nitrogen content was acceptable for barley and millet groups but low for the sorghum group (9.60%). The wort color was darker for the millet (8.89 and 12.89 EBC units) than sorghum (5.11 EBC units) and the barley (4.70 EBC units) groups. Wort filtration of Kenyan sorghum required longer times than barleys and USA millet but not longer than Kenyan millet. Saccharification times for all millets and sorghum groups were excessively long (≥20 min). Barley groups produced standard brewers malts at 14°C for 6 days and at 18 and 22°C for 4 days. Millet and sorghum groups did not produce useful malt at 14°C but the malt characteristics were better at 18°C for 6 days and 22°C for 4 days.;The highest levels of malt polyphenols (1.288% dry matter) and tannins (1.425% dry matter) were found in the sorghum group; however, the highest value for wort polyphenols were in the Kenyan millet group (0.013% dry matter). Barley grains had the highest diastatic power; alpha amylase was similar for all groups. Diastatic power in the malt from all groups indicated barleys (116.50 DP°ASBC) were more than eight times greater than millets groups (13.22 DP°ASBC) and sorghum (4.37 DP°ASBC) was the lowest. The malt alpha amylase content of the sorghum group was extremely low (4.63 DU's).;The content of four sugars was determined in all grain, malt and wort samples. Analysis of malts indicated large differences in maltose content with barley having the highest values (2.32%) and sorghum (0.342%) and millet (0.20%) groups having much lower values. There was less variation of malt fructose, glucose and sucrose contents than maltose content. (Abstract shortened by UMI.)