Wet vacuum impregnation assisted in malting; its implication on steeping degree, germination energy and malt properties

Abstract

SummaryThe wet vacuum impregnation (WVI) was used in malting process to reduce soaking period. To implement WVI during steeping, vacuum pressure of 500 mmHg for 300 s, was applied twice on five Thai barley cultivars. The effect of WVI on germination energy, moisture content, phenolic acids, antioxidant activity (AOA) and malt quality were examined relative to Central European Commission for Brewing Analysis (MEBAK) malting condition. Moisture content in barley soaked by WVI and MEBAK steeping method were in the range of 36.1–39.9% and 39.9–47.8%, respectively with germination energy of 96–97%. The physicochemical properties of malt from steeping via WVI and MEBAK showed the malts were protein‐rich cultivars, adequate β enzyme and low α amylase activities, hence, low‐malt extract. Total fermentable sugars were relative higher in MEBAK malts than WVI malts. Nevertheless, steeping by WVI had higher free and bound phenolic acids, which led to higher AOA via ABSTS and DPPH assays in some barley cultivars than MEBAK. This research highlights the WVI did not limit barley gemination and the potential of this technology in malting process by limiting steeping time. Further study is required to reduce air‐rest period and optimise condition to achieve moisture content of 40–45% in soaked barley.