VIEW ARTICLE    http://dx.doi.org/10.1094/ASBCJ-2012-0906-01

Comparisons of Amylolytic Enzyme Activities and beta-Amylases with Differing Bmy1 Intron III Alleles to Sugar Production During Congress Mashing With North American Barley Cultivars (1). Stanley H. Duke (2), Department of Agronomy, University of Wisconsin, Madison, WI, Marcus A. Vinje, United States Department of Agriculture-Agricultural Research Service, Cereal Crops Research Unit, Madison, WI, and Cynthia A. Henson, United States Department of Agriculture-Agricultural Research Service, Cereal Crops Research Unit, and Department of Agronomy, University of Wisconsin, Madison, WI. (1) Mention of a proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other suitable products. (2) Corresponding author. Phone: +1-608-262-6527, fax: +1-608-890-0306, e-mail: <shduke@wisc.edu> J. Am. Soc. Brew. Chem. 70(4):230-248, 2012.

This study was conducted to determine the relationships between patterns of activity of malt amylolytic enzymes (alpha-amylase, beta-amylase, and limit dextrinase) and sugar production in two- and six-row North American cultivars over the course of Congress mashing and to test two hypotheses: 1) that maximal activity of and rates of increase in beta-amylase activity during the initial phases of mashing would correlate better than the other amylolytic enzymes with sugar production and 2) that beta-amylase intron III allelic variation would have little to no association with sugar production during mashing. Malts of twelve barley cultivars were mashed in a micro-masher and assayed for amylolytic enzyme activities and sugar levels at 6 time points during the 115 min mashing regime. Peak activities of beta-amylase were positively and significantly correlated with wort total sugars (r = 0.704, P = 0.011), glucose (r = 0.654, P = 0.021), and maltose (r = 0.780, P = 0.003) and negatively and significantly correlated with maltotetraose (r = –0.830, P = 0.001) and maltopentaose (r = –0.767, P = 0.004). In contrast, with the same comparisons, there were no significant correlations with wort total sugars for alpha-amylase and limit dextrinase and only alpha-amylase significantly correlated with some individual sugars (glucose, r = 0.611, P = 0.035; maltotriose, r = 0.594, P = 0.042; maltotetraose, r = –0.772, P = 0.003; maltopentaose, r = –0.728, P = 0.007). Correlations of rates of change in beta-amylase activity from five min to the time of maximal activity versus rates of change in total sugars and individual sugars revealed positive and significant correlations with wort total sugars (r = 0.794, P = 0.002), maltose (r = 0.851, P = 0.0004), and maltotriose (r = 0.605, P = 0.038) and significantly negatively correlated with maltotetraose (r = –0.663, P = 0.019) and maltopentaose (r = –0.677, P = 0.016). In contrast, with the same comparisons, there were no significant correlations with wort total sugars or individual sugars versus alpha-amylase or limit dextrinase. Least significant difference (LSD) analysis revealed that there was no consistent pattern in total wort sugars and the most and least abundant wort sugars and maltodextrins produced during mashing amongst cultivars with Bmy1.a or Bmy1.b intron III alleles. There were no significant differences in cultivars with Bmy1.a or Bmy1.b intron III alleles producing the highest levels of total wort sugars early in mashing, when the bulk of total sugars are produced, (1st 30 min: Bmy1.a [Legacy, Tradition]; Bmy1.b [Harrington]) and at the end of mashing (Bmy1.a [Legacy, Pinnacle, Tradition]; Bmy1.b [Harrington, Merit]). This study supports both of the proposed hypotheses. Keywords: alpha-Amylase, beta-Amylase, Bmy1 Intron III alleles, Limit dextrinase, Mashing, Wort sugars

Este estudio se realizó para determinar las relaciones entre los patrones de actividad de las enzimas amilolíticas malta (alfa-amilasa, beta-amilasa, y dextrinasa límite) y la producción de azúcar en dos-fila y en seis-fila cultivares norteamericanos en el transcurso del maceración Congreso y poner a prueba dos hipótesis: 1) que la actividad máxima de y tasas de aumento de beta-amilasa durante las fases iniciales de maceración se correlacionan mejor que las otras enzimas amilolíticas con la producción de azúcar, y 2) que beta-amilasa intrón III variación alélica tiene que poca o ninguna relación con la producción de azúcar durante la maceración. Maltas de 12 cultivares de cebada fueron macerado en un micro-macerador y se ensayó la actividad de las enzimas amilolíticas y los niveles de azúcar en seis puntos de tiempo durante el régimen de 115 min del maceración. Actividades máximas de beta-amilasa eran positiva y significativamente correlacionado con azúcares totales del mosto (r = 0.704, P = 0.011), glucosa (r = 0.654, P = 0.021) y la maltosa (r = 0.780, P = 0.003) y negativa y significativamente correlacionado con maltotetraosa (r = –0.830, P = 0.001) y maltopentaosa (r = –0.767, P = 0.004). En contraste, con las mismas comparaciones, no hubo correlaciones significativas con los azúcares del mosto total para la alfa-amilasa y dextrinasa límite y sólo la alfa-amilasa significativamente correlacionada con algunos azúcares individuales (glucosa, r = 0.611, P = 0.035; maltotriosa, r = 0.594, P = 0.042; maltotetraosa, r = –0.772, P = 0.003; maltopentaosa, r = –0.728, P = 0.007). Correlaciones de tasas de cambio en la actividad de beta-amilasa de 5 minutos hasta el tiempo de máxima actividad frente a tasas de cambio en azúcares totales y azúcares individuales reveló una correlación positiva y significativa con los azúcares totales del mosto (r = 0.794, P = 0.002), maltosa (r = 0.851, P = 0.0004), y maltotriosa (r = 0.605, P = 0.038) y significativamente correlacionado negativamente con maltotetraosa (r = –0.663, P = 0.019) y maltopentaosa (r = –0.677, P = 0.016). En contraste, con las mismas comparaciones, no hubo correlaciones significativas con los azúcares del mosto totales o azúcares individuales frente a alfa-amilasa o dextrinasa límite. Diferencia mínima significativa (LSD) reveló que no hubo un patrón consistente en azúcares totales del mosto y la mayoría y menos de las azúcares abundantes del mosto y las maltodextrinas producidos durante la maceración entre cultivares con Bmy1.a o Bmy1.b intrón III alelos. No hubo diferencias significativas en los cultivares con Bmy1.a o Bmy1.b intrón III alelos que producen los más altos niveles de azúcares totales del mosto a principio de la maceración, cuando la mayor parte de los azúcares totales se producen, (primero 30 min: Bmy1.a [Legacy, Tradition]; Bmy1.b [Harrington]) y al final de la maceración (Bmy1.a [Legacy, Pinnacle, Tradition]; Bmy1.b [Harrington, Merit]). Este estudio apoya dos de las hipótesis propuestas. Palabras claves: alfa-Amilasa, beta-Amilasa, Bmy1 intrón alelos III, Dextrinasa límite, Los azúcares del mosto, Maceración