Sorghum β-Amylase Production: Relationship With Grain Cultivar, Steep Regime, Steep Liquor Composition and Kilning Temperature

Abstract

Steep regime, nature of alkaline liquor, and kilning conditions were studied for their effects on sorghum malt ␤-amylase development in four Nigerian sorghum cultivars. Malt ␤-amylase activity was markedly (p < .001) influenced by all the four factors as well as their various interactions. Overall, malts from KSV 8 variety were the most ␤-amylolytic followed in sequence by those from Local Red (LR), SK 5912, and Local white (LW) respectively. The presence or absence of air rests in steep regimes was a significant (p < .001) determinant of sorghum ␤-amylase response to final warm steeping, steep liquor and kilning condition. The nature of the alkaline steep liquor was also a major determinant of the pattern of malt ␤-amylase response to the kilning condition. Steeping in Ca(OH) 2 enhanced malt ␤-amylase activity at the higher temperature of kilning, while KOH produced the opposite effect. Ca(OH) 2 enhancement of ␤-amylase development, at a kilning temperature of 50°C, was varietydependent suggesting that different sorghum cultivars may employ different biosynthesis models for ␤-amylase synthesis. The regime-dependence of ␤-amylase response to kiln temperature suggests that this was an important modulator of sorghum germination physiology.Key words: Alkaline liquor, ␤-amylase, kilning temperature, sorghum malt, steeping regime, cultivars. -2863(9'8-32␤-Amylase is the key saccharifying enzyme of the brewers' malt 22 . While the low ␤-amylase activity of sorghum malts has been defined as one of the most serious obstacles to its use as replacement for barley malt 2 , results of recent studies using some improved varieties of the grain suggest that the production of high ␤-amylasecontaining sorghum malts may be possible with the proper choice of variety and conditions of malting 9,10,[25][26][27] . Recent research has shown that sorghum malt ␣-amylase level is critically correlated with environmental conditions of steeping and kilning 24 . While some work has been conducted on the effects of environmental conditions of steeping on sorghum malt ␤-amylase levels, very few data are available with respect to the effects of kilning conditions on the development of the sorghum enzyme 29 . In this communication, we present the effects of kilning conditions on the ␤-amylase activity of sorghum malts prepared from different cultivars, and under varying conditions of steeping including dissimilar steep liquors as well as different steeping regimes. 1%8)6-%07 %2( 1)8,3(7 7SYVGIW SJ WSVKLYQ GYPXMZEVWCultivars SK 5912 and KSV 8 were improved varieties obtained from the National Seeds Service, Zaria, Nigeria. Grains of the local white (LW) and the local red (LR) varieties were purchased from the open market at Nsukka, Nigeria. Germinative energies were above 95% for all the grains and none was water-sensitive. 7SVKLYQ QEPXMRKThe grains were sorted manually to remove broken kernels and debris. Alkaline steeping was carried out using glass-distilled water containing 0.1% of the alkali (NaOH, KOH, or Ca(OH) 2 ). Double glass-distilled...

The Impact of Kilning on Enzymatic Activity of Buckwheat Malt

“…3 shows that in the first 7 h of kilning, total ␤-amylase activity level in buckwheat malt increased from 23.1 units g -1 to 28.1 units g -1 . This confirms the findings of Okungbowa et al 30 , where it was noted that when kilning sorghum at lower temperatures, i.e. 40°C, the enzyme denaturing phase is avoided and increased enzyme development is observed.…”

“…40°C, the enzyme denaturing phase is avoided and increased enzyme development is observed. In addition, possible proteolytic activation of ␤-amylase zymogens during the enzymatic phase of malt kilning may in part account for the increase in total ␤-amylase activity 11,22,30 . Over the following 41 h total ␤-amylase activity decreased from 28.1 units g -1 to 26.4 units g -1 .…”

Measuring Hordein (Gluten) in Beer – A Comparison of ELISA and Mass Spectrometry

“…Brewing with less immunogenic grains such as oats, and gluten-free grains such as buckwheat, sorghum and millet have also been reported [28], [29], [30], [31], [32].…”

The Influences of Steeping Duration and Temperature on the α- and β-Amylase Activities of Six Thai Rice Malt Cultivars (Oryza sativa L. Indica)

“…Among these enzymes, there are two important enzymes that control malt quality, α-amylase and diastase; a group of enzymes that digest starch 3 . Therefore, the investigation of malting conditions deals with factors which affect activities, such as steeping conditions 5,8,19 , steeping duration 25 , germination temperature 4 , grain property and cultivar 11 . Most of the studies on malting conditions have been carried out with barley, sorghum, and wheat.…”