Evaluation of using the rice in Mekong Delta for beer making: Nutritional, heat‐resistant, protease‐resistant, and inhibitor properties of proteins

Abstract

The aim of this study was to evaluate whether IR50404-resistant protein (RP) rice is suitable for brewing. So, the RP was soaked in water pH 6.6 at room temperature for 24 h and germinated for 4 days to get green malt. This malt was dried at 50°C for 24 h to get rice malt (RM). The RM was mashed with an adjusted EBC program before being fermented by yeast at 13°C for 4 days to get rice beer (RB). The results showed that protein in RM showed a statistical difference in inhibitory zone diameter for proteinase K, which is similar to barley malt. Heat- and protease-resistant proteins (HPRPs) in RM were ranged between 14.4 and 55–70 kDa. The HPRPs were detected as an alpha-amylase/trypsin inhibitor (~14.4 kDa) in wort and RB. The beer foam was stable from 5 to 25 min after shacking. Therefore, IR50404 contains HPRPs that contribute to the stability of the foam of the RB. Novelty impact statement It is necessary to find a method to determine the possibility of a rice variety in the Mekong Delta region can be used for beer making. This study focused on the heat- and protease-resistant/inhibitor properties of the protein because the brewing process is always accompanied by heating and the presence of protease from yeast. So, the presence of these proteins group during malting and after beer fermentation could contribute to the stability of clarification as well as foam establishment and foam stability of rice beer. The results of this study indicate that the rice variety IR50404 was completely usable for beer making. This property is also an indicator for selecting rice that is suitable for beer making.