ASBC Journal 2007 - Green Malt Osmolyte Concentration as an Early Indicator of Finished Malt Quality.

Journal Overview
Publication Notice
Table of Contents
Search Abstracts
Sample Issue
Subscribe
Masthead
Editorial Policy
Author Instructions

VIEW ARTICLE doi:10.1094/ASBCJ-2007-0612-02

Green Malt Osmolyte Concentration as an Early Indicator of Finished Malt Quality (1). Stanley H. Duke (2), Department of Agronomy, University of Wisconsin, Madison, WI; and Cynthia A. Henson, USDA-ARS Cereal Crops Research Unit, Madison, WI, 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. Department of Agronomy, 1575 Linden Dr., University of Wisconsin, Madison, WI 53706. E-mail: <shduke@wisc.edu>; Phone: +1.608.262.6527; Fax: +1.608.262.4282. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Society of Brewing Chemists, Inc., 2007. J. Am. Soc. Brew. Chem. 65(3):145-150, 2007.

This study was conducted to test the hypothesis that barley green malt osmolyte concentration (GMOC) can be used as an early indicator of finished barley malt quality. Seeds of three two-row genotypes and three six-row genotypes were steeped and germinated in a mircomalter for 6 days. At intervals of 24 hr over the germination regime, green malt from each cultivar was both removed and tested for GMOC and kilned and analyzed for the finished malt quality measurements of malt extract (ME), diastatic power (DP), alpha-amylase activity, soluble protein/total protein (S/T), and beta-glucan concentration. GMOC values increased most rapidly from days one to three of germination. For all but one genotype, the rates of increase in GMOC values after 3 days began to slow or plateau. ME values followed a pattern over time similar to that of GMOC; however, the rates of increase in ME levels began to slow or plateau sooner than for GMOC values. ME and GMOC values for all genotypes combined and for each genotype individually were significantly and positively correlated over the 6 days of germination (r = 0.840, P < 0.0001 [combined genotypes]; r = 0.878–0.943, P < 0.0001 [individual genotypes]). Significant correlations also were found between GMOC and other finished malt quality parameters over the 6 days of germination for all genotypes combined and for each individual genotype (alpha-amylase activity, DP, and S/T were positive, r = 0.757–0.856, P < 0.0001 [combined genotypes], and r = 0.737–0.944, P = 0.0006 to <0.0001 [individual genotypes]; beta-glucan concentrations were negative, r = –0.851, P < 0.0001 [combined genotypes], and r = –0.788 to –0.896, P = 0.0001 to <0.0001 [individual genotypes]). GMOC values on day one were significantly and positively correlated with ME on days one through five (r = 0.756–0.886, P = 0.0003 to <0.0001) and alpha-amylase on days one through five (r = 0.635–0.776, P = 0.0046–0.0002). GMOC values on day two were significantly and positively correlated with ME on days one through six (r = 0.769–0.910, P = 0.0002 to <0.0001) and alpha-amylase activity and S/T on days three through six (r = 0.733–0.890, P = 0.0005 to <0.0001). This indicates that GMOC values from early periods in germination (days one and two) are good indicators of finished malt ME and other finished malt quality values for malt produced 1–4 days later. Keywords: alpha-Amylase, Green malt, Malt extract, Malt quality, Osmolytes

Este estudio fue conducido para probar la hipótesis que la concentración del osmolios de la malta verde de cebada (GMOC) se puede utilizar como indicador temprano de la calidad de la malta final de cebada. Las semillas de tres genotipos de dos-fila y tres genotipos de seis-fila fueron empapadas y germinaron en un mircomalteado por 6 días. En los intervalos de 24 hr sobre el régimen de la germinación, la malta verde de cada cultivar fue quitada y probada para GMOC y secada y analizada para las medidas de calidad de la malta final del extracto de malta (ME), el poder diastásico (DP), la actividad de alfa-amilasa, la proteína soluble/total (S/T), y la concentración de los beta-glucanos. Los valores de GMOC aumentaron lo más rápidamente entre los primero y tercero días de germinación. Para todos sino un genotipo, los coeficientes de incremento en valores de GMOC después de 3 días comenzaron a retardarse o mantenerse Los valores de ME siguieron un patrón en un cierto plazo similar del GMOC; sin embargo, los coeficientes de incremento en niveles de ME comenzaron a retardarse o mantenerse más pronto que los valores de GMOC. Los valores de ME y GMOC para todos los genotipos combinados y para cada genotipo individualmente fueron correlacionados perceptiblemente y positivamente sobre los 6 días de la germinación (r = 0.840, P < 0.0001 [los genotipos combinados]; r = 0.878–0.943, P < 0.0001 [genotipos individuales]). Las correlaciones significativas también fueron encontradas entre GMOC y otros parámetros de calidad de la malta final sobre los 6 días de la germinación para todos los genotipos combinados y para cada genotipo individual (la actividad de la alfa-amilasa, el DP, y S/T eran positivos, r = 0.757–0.856, P < 0.0001 [los genotipos combinados], y r = 0.737–0.944, P = 0.0006 a <0.0001 [genotipos individuales]; las concentraciones de los beta-glucanos eran negativas, r = –0.851, P < 0.0001 [los genotipos combinados], y r = –0.788 a –0.896, P = 0.0001 a <0.0001 [genotipos individuales]). Los valores de GMOC en el primero día fueron correlacionados perceptiblemente y positivamente con el ME en días uno a cinco (r = 0.756–0.886, P = 0.0003 a <0.0001) y alfa-amilasa en días uno a cinco (r = 0.635–0.776, P = 0.0046–0.0002). Los valores de GMOC en el segundo día fueron correlacionados perceptiblemente y positivamente con el ME el días uno a seis (r = 0.769–0.910, P = 0.0002 a <0.0001) y actividad de la alfa-amilasa y S/T en días tres a seis (r = 0.733–0.890, P = 0.0005 a <0.0001). Esto indica que los valores de GMOC a partir de períodos tempranos en la germinación (días uno y dos) son buenos indicadores del ME de la malta final y otros valores de calidad de la malta final para malta produjera 1–4 días más adelante. Palabras claves: alfa-Amilasa, Calidad de la malta, Extracto de malta, Malta verde, Osmolitos

Buy this article.

A subscription to the Journal of the American Society of Brewing Chemists is complimentary with membership to the ASBC.

The ASBC Journal publishes scientific papers, review articles, and technical reports dealing with the chemistry and microbiology of brewing ingredients and relevant technology, as well as the analytical techniques used in the malting and brewing industry.