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VIEW ARTICLE doi:10.1094/ASBCJ-2007-1214-01
Evaluation of Indigenous Botswana Sorghum Cultivars with Respect to their Diastatic Power, alpha-Amylase, beta-Amylase, and Limit Dextrinase Potentials for Malting. Rebaone Letsididi, Bernard Bulawayo, and Martin Kebakile (1), Microbiology and Biotechnology Unit, National Food Technology Research Centre, Kanye, Botswana; and Lewis Iheanacho Ezeogu (2), Department of Microbiology, University of Nigeria, Nsukka, Nigeria. (1) Current address: Department of Food Science, University of Pretoria, 0002 Pretoria, South Africa. (2) Corresponding author. National Food Technology Research Centre, P/B 008, Kanye, Botswana. E-mail: <lewis@naftec.org> or <lewisih@gmail.com>; Phone: +267 544 2448, +267 544 0441, or +267 7132 0957; Fax: +267 544 0713. J. Am. Soc. Brew. Chem. 66(1):29-36, 2008.
The malting quality of 11 Botswana sorghum cultivars was assessed using their diastatic power (DP), alpha-amylase, beta-amylase, and limit dextrinase (LD) potentials as parameters. Malt DP and LD were assayed using soluble starch and Limit-Dextrizyme methods, respectively. Malt alpha- and beta-amylase activities were assayed specifically with Ceralpha and Betamyl, respectively, then nonspecifically with a diamylase method in which beta-amylase activity is denatured by heating (70°C, 15 min). All malt quality parameters varied significantly (P < 0.001) by grain cultivar. Malt DP, alpha-amylase, and beta-amylase fell within ranges previously reported for industrial sorghum malts. beta-Amylase was the principal amylase component of DP in BSH1, Lekgeberwa, SNK, Kanye Standard, Marupantshi, and Mafia at 55, 68, 71, 72, 75, and 88%, respectively. Malt LD was high at 101 (Mafia) to 231 U (Sefofu). For alpha- and beta-amylase, values obtained using both specific assay methods correlated strongly (R(^2) = 0.94, P < 0.001 for alpha-amylase; R(^2) = 0.95, P < 0.001 for beta-amylase) with results from the diamylase protocol. The results highlight the need to screen more cultivars for brewing properties. Segao, Lekgeberwa, Sefofu, Town, and Kanye Standard displayed desirable amylolytic properties, suggesting their potential use in the production of lager beer-quality sorghum malts. Keywords: alpha-Amylase, beta-Amylase, Diastatic power, Limit dextrinase, Malting, Sorghum
La calidad de malteado de 11 Botswana cultivares de sorgo se evaluó
mediante su energía diastásica (ED), alfa-amilasa, beta-amilasa, y
dextrinasa límite (LD) potenciales como parámetros. ED y LD de la malta
fueron ensayadas utilizando almidón solubles y métodos de
Limit-Dextrizyme, respectivamente. Actividades de alfa- y beta-amilasa en
la malta fueron ensayadas específicamente con sistemas de Ceralpha y
Betamyl, respectivamente, y después sin-específicamente con un diamilasa
método en que la actividad de beta-amilasa es desnaturalizado con calor
(70°C, 15 min). Todos los parámetros de calidad de malta variado
significativamente (P < 0.001) entre los cultivares de grano. ED de
la malta, alfa-amilasa, beta-amilasa, y cayó dentro de las gamas ya se ha
informado para el sector de sorgo maltas. beta-Amilasa es el principal
componente de ED en BSH1, Lekgeberwa, SNK, Kanye Estándar, Marupantshi, y
la Mafia en 55, 68, 71, 72, 75, y 88%, respectivamente. LD de la malta era
elevado en 101 (Mafia) a 231 U (Sefofu). Para alfa- y beta-amilasa, los
valores obtenidos utilizando los dos métodos específicos correlacionado
fuertemente (R(^2) = 0.94, P < 0.001 para alfa-amilasa; R(^2)
= 0.95, P < 0.001 para beta-amilasa) con el resultado de la
protocolo de diamilasa. Los resultados destacan la necesidad de evaluar
más cultivares para propiedades relacionado con la fabricación de cerveza.
Segao, Lekgeberwa, Sefofu, Población, y Kanye Estándar mostradas
propiedades amilolíticas deseable, lo que sugiere su posible uso en la
producción de sorgo maltas de la calidad de la cerveza tipo lager.
Palabras claves: alfa-Amilasa, beta-Amilasa, Dextrinasa límite, Energía
diastásica, Malteado, Sorgo
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