Development of a fast and reliable microwave-based assay for measurement of malt color

Analytical Session
Yin Li, Malteurop North America Inc, Milwaukee, Wisconsin, 53215
Co-author(s): Mary-Jane Maurice, Malteurop North America Inc., Milwaukee, WI, USA

ABSTRACT: The ASBC color method (Wort-9) has been widely accepted and used in the malting and brewing industries to determine wort color and is based on the measurement at a single wavelength (430 nm) using a spectrophotometer. However, this method is time-consuming and needs clarified wort generated from Congress mash. It is impossible for satellite laboratories without mashing baths to obtain results. Therefore, the major challenge is to set up a fast and reliable wort color assay method without a routine mashing procedure. In this study, we successfully established a novel and quick method for the measurement of wort color without Congress mashing based on the simulation of mashing by microwave technology. Three important factors involved in the new method, including microwave power, heating time, and grist to water ratio, have been optimized by a randomized complete block statistical design (RCBD). The new method is able to obtain a color result within 30 min. The standard deviation of the new method ranged from 2.4 to 2.8%, suggesting the reproducibility of the new method is very reliable. Forty-five malt samples were measured by both the novel and Wort-9 methods. The results suggested that the new method showed a good correlation (r = 0.95) with the ASBC color method, and the difference between the two methods was less than 10%. We feel the method would be of interest to maltsters for quickly checking their shipment samples to brewers and would be useful for those laboratories without mashing equipment. Microwave mashing also utilizes less expensive equipment, making it suitable for more laboratories.

Yin Li is a quality assurance manager at Malteurop North America, Inc. Before joining Malteurop, Yin was a research assistant professor in the Department of Plant Sciences at North Dakota State University (NDSU). He received his Ph.D. degree in fermentation engineering from the School of Biotechnology at Southern Yangtze University in Wuxi, China, working on research in the area of malting and brewing, and did his post-doctoral research work with Paul Schwarz at NDSU. He has published more than 40 papers in international peer-reviewed journals in malting and brewing areas, as well as one book chapter, “Malting and Brewing Uses of Barley.” He is the winner of 2007 AACC International Bruce Wasserman Young Investigator Award. Yin has served as a reviewer for more than 10 journals in cereal and food sciences and is an editorial board member of the Journal of the Institute Brewing.