Our study showed that sorghum and millet followed a similar pattern of changes when they were malted under similar conditions. When the malt from these cereals was mashed, both cereal types produced wide spectra of substrates (sugars and amino acids) that are required for yeast fermentation when malted at either lower or higher temperatures. At the germination temperatures of 20, 25, and 30 °C used in malting both cereal types, production of reducing sugars and that of free amino nitrogen (FAN) were similar. This is an important quality attribute for both cereals because it implies that variation in temperature during the malting of sorghum and millet, especially when malting temperature is difficult to control, and also reflecting temperature variations, experienced in different countries, will not have an adverse effect on the production and release of amino acids and sugars required by yeast during fermentation. Such consistency in the availability of yeast food (substrates) for metabolism during fermentation when sorghum and millet are malted at various temperatures is likely to reduce processing issues when their malts are used for brewing. Although sorghum has gained wide application in the brewing industry, and has been used extensively in brewing gluten-free beer on industrial scale, this is not the case with millet. The work described here provides novel information regarding the potential of millet for brewing. When both cereals were malted, the results obtained for millet in this study followed patterns similar to those of sorghum. This suggests that millet, in terms of sugars and amino acids, can play a role similar to that of sorghum in the brewing industry. This further suggests that millet, like sorghum, would be a good raw material for brewing gluten-free beer. Inclusion of millet as a brewing raw material will increase the availability of suitable materials (raw material sustainability) for use in the production of gluten-free beer, beverages, and other products. The availability of wider range of raw materials will not only help to reduce costs of beer production, but by extension, the benefit of reduced cost of production can be gained by consumers of gluten-free beer as the product would be cheaper and more widely available.

J. Inst. Brew. 116(2), 125-133, 2010This study showed that when barley was steeped in water for either 8 h or 16 h, hydration of endosperm materials was suboptimal and modification of endosperm materials of barley malt was inadequate. The malt produced under these steeping regimes gave poor friability scores and produced a large number of whole grains. When barley was steeped for 24 h on a continuous basis, or when a regimented standard steeping method was used, the malt produced gave higher friability scores and a much lower number of whole grains. An important relationship was found between friability scores and whole grain results for the malt samples produced under these conditions. Optic barley, whose endosperm was more difficult to hydrate, gave a strong negative correlation between friability scores and number of whole grains at R 2 = 0.8689. Oxbridge, whose endosperm was more easily hydrated, gave a much stronger negative correlation between friability scores and number of whole grains at R 2 = 0.9769. Rapid visco-analysis (RVA) results also confirmed that steeping the barley samples for only 8 h or 16 h produced malt that modified poorly as the RVA peak viscosities were very high. RVA pasting results further confirmed that when barley was steeped for 24 h on a continuous basis, or when a standard regimented steeping method was used, good quality malt was produced and no differences were found in the RVA peak viscosities of the barley malt samples produced under the two different steeping conditions. The results of protein breakdown (proteolysis) during these experiments, measured in terms of total soluble nitrogen (TSN) production, or soluble nitrogen ratio (SNR) further confirmed that optimal proteolysis was achieved when barley was steeped for either 24 h on a continuous basis, or with a standard steep. Optimal results were also found for hot water extractable materials such as hot water extract (HWE) and free amino nitrogen (FAN) when barley was steeped for 24 h or the standard steep. The 24 h continuous steep for barley produced quality malt comparable to that obtained when the standard regimented steep was used for steeping barley. For both Optic and Oxbridge barley, with a 24 h continuous steep, produced malt that gave significantly higher fermentabilities and PSY values, regardless of germination time, than those obtained using a standard regimented steep. Therefore steeping barley for 24 h on a continuous basis prior to malting will produce good quality malt for some barley samples/varieties. This will help to reduce water usage during steeping, will save steeping time thereby reducing malting time and will reduce the amount of water for effluent treatment. All of these factors result in an overall cost saving for the malting industry.

This study examined the performance of rice and buckwheat when malted under various temperature conditions and for different lengths of time. The mashed malts produced from both rice and buckwheat contained a wide spectra of sugars and amino acids that are required for yeast fermentation, regardless of malting temperature. At the germination temperatures of 20, 25, and 30 °C used, production of reducing sugars and free amino nitrogen (FAN) followed similar patterns. This implies that temperature variations, experienced in different countries, will not have an adverse effect on the production and release of amino acids and sugars, required by yeast during fermentation, from these grains. Such consistency in the availability of yeast substrates is likely to reduce differences in processing when these malts are used for brewing. This study revealed that, while rice malt consistently produced more maltose than glucose, buckwheat malt gave several times more glucose than maltose, across all germination temperatures. Buckwheat malt also produced more soluble and free amino nitrogen than rice malt. Unlike sorghum, which has gained wide application in the brewing industry for the production of gluten-free beer, the use of rice and buckwheat is minimal. This study provides novel information regarding the potential of rice and buckwheat for brewing. Both followed similar patterns to sorghum, suggesting that they could play a similar role to sorghum in the brewing industry. Inclusion of rice and buckwheat as brewing raw materials will increase the availability of suitable materials for use in the production of gluten-free beer, potentially making it more sustainable, cheaper, and more widely available.

A sorghum variety was supplied as commercial malt and as an unmalted cereal by a maltster. The commercial sample had been malted in a tropical country. Sub-samples of the unmalted cereal were malted in the laboratory under controlled germination temperatures of 28°C and 30°C. Laboratory and commercially malted sorghum were studied for their brewing qualities. The α-amylase development in sorghum malt was enhanced when germination was carried out at the higher temperature of 30°C rather than at 28°C. Hot water extract (HWE) was more variable. With infusion mashing, results showed a significant difference for germination time (3-6 days), but no significant difference relating to germination temperature. With the decantation mashing method the reverse was observed. The low numerical values of HWE obtained from sorghum malt in the infusion mashing process confirmed that this process is not suitable to produce optimal extract development from malted sorghum. The 28°C germinated sorghum released more FAN products into the worts than the 30°C malt, using both the infusion and decantation methods. With regard to the parameters tested, commercially malted sorghum gave lower analytical values than laboratory malted sorghum. It was also observed that variations in malting temperatures and mashing processes can cause unexpected variations in the analyses of sorghum malt. These findings suggest that careful process control is required during the malting and mashing of sorghum.

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