Malting and Brewing Qualities of Globally Sourced Rice Cultivars

Malting is the controlled germination of cereal grains, with the primary objective of promoting the development of hydrolytic enzymes. Malt prepared from barley is by far the most important. However, malt from other cereals including rice has gained significant interest in recent years due to economic considerations and local availability. The search for these alternative sources is also driven by the need to enhance the value of local raw materials, expand market opportunities for farmers and strengthen agricultural economies. Despite this growing interest, limited data exist on the malting performance of diverse rice cultivars. Recent research in our lab screened 19 rice cultivars for their malt quality traits and identified various desired traits such as self-saccharification, relatively high extract, high limit dextrinase and glucosidase activities, and sufficient free amino nitrogen (FAN) and protein concentrations. However, the diastatic power (DP) of rice malt (< 100 °WK) was significantly lower than that of barley (250 °WK) highlighting a critical limitation in α and β amylases activity. To further expand this knowledge, our current study evaluated the malting potential of a diverse rice germplasm collected from different countries across Asia, Africa, Europe, and the Americas. This broad geographic representation aimed to identify cultivars with superior malting properties while providing insights into their biochemical potential, adaptability, and suitability for brewing and food applications. To achieve this goal, a benchtop malting system was optimized for rice grain malting, following previously established malting parameters with slight modifications. Congress mash was conducted at a small-scale using microcentrifuge tubes. The resulting malt was analyzed using standard quality tests, including extract, DP, amylases activity, and wort composition (soluble protein, Kolbach index, and FAN levels). This study identified promising rice cultivars with enhanced malting properties, including higher diastatic power, improved starch hydrolysis, and favorable protein modifications, which could make them suitable alternatives or adjuncts to barley malt. Additionally starch qualities such as apparent amylose content as well as onset, peak, and end gelatinization temperatures were measured to assess their influence on malting and brewing performance. The observed variations in malting traits provide a foundation for identifying genetic markers associated with malt quality, facilitating targeted breeding strategies to enhance rice’s suitability for malting. Moreover, by evaluating a broad range of geographically diverse rice cultivars, the study provided insights into natural variability in malting traits, helping to identify region-specific rice varieties with superior brewing potential and possible directionality in breeding for malting qualities. Overall, this study contributes to the development of rice-based beverages, particularly for regions where rice is abundant and barley is scarce, ultimately supporting locally sourced material and the malting/brewing industries.