Evaluation of optimal malting conditions of three rice varieties for improved brewing trials
Date
2023-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Federal University of Technology, Owerri
Abstract
Gluten-free beer could be produced with rice, although the latter would primarily serve as an adjunct in combination with barley malt in today’s brewing. But, the recent growing realisation of the potentials and applications of rice malt for brewing an all-rice malt beer through varying malting conditions cannot be overlooked. In this current study, therefore, the characteristic changes in malt, wort and beer from different Nigerian rice varieties (FARO 44, FARO 57, NERICA 7) as influenced by varying malting conditions (steeping duration [18, 24 and 30 h], germination periods [2, 3 and 4 days] and kilning temperatures [50 and 55 °C]), were investigated. Rice (grain) samples were examined by thousand corn weight Germinative Energy, Germinative Capacity, and Degree of Steeping. To ensure that rice wort/beer of unique beer style and enhanced attributes comparable to barley wort/beer is produced, only malting conditions that delivered rice malts with peak Diastatic Power, Cold Water Extract and Hot Water Extract were selected. Peak Diastatic Power, Cold Water Extract and Hot Water Extract wereobtained at FARO 44 [18h steeping, 3days germination, 55°C kilning (S18G3K55°)], FARO 57 [30h steeping, 2days germination, 50°C kilning (S30G2K50°)] and NERICA 7 [24h steeping, 3days germination, 55°C kilning (S24G3K55°)]. Selected malts were further tested for Moisture Content, Total Nitrogen, Malt Yield, and Malting Loss, which subsequently progressed to wort and beer production. Wort’s pH, Total Soluble Nitrogen, Brix, Kolbach Index, Free Amino Nitrogen, Dextrose Equivalent, Original Extract, and Sugar Profile were determined, as well as beer’s pH, Colour, Apparent Extract, Alcohol by volume (%ABV), Turbidity, and Sensory attributes. Rice grains’ Thousand Corn Weight, Germinative Energy, germinative Capacity, and Degree of Steeping significantly varied (p<0.05) across varieties. Despite wort’s pH, Total Soluble Nitrogen, Dextroxe Equivalent, Original Extract as well as beer pH, Colour, Apparent Extract, and Turbidity resembled (p>0.05) across varieties, the wort’s Brix, Kolbach Index, Free Amino Nitrogen, Sugar profile as well as beer’s %ABV, differed significantly (p<0.05). Sensory attributes of appearance, colour, mouthfeel, and overall acceptability in beer differed noticeably (p<0.05), except for both aroma and taste (p>0.05). Overall, the rice beer, though very slightly hazy, represented a pale yellow light lager, which suggested a peculiar beer style. In addition to benefits of increased Diastatic Power and enhanced hydrolysis, varying malting conditions could be key in reducing the cost of exogenous (commercial) enzymes or barley malt imports, together with decreasing barley’s dependency for brewing in the tropics.
Description
This thesis is for the award of Master of Science (MSc.) in Food Science and Technology (Food Processing Technology option)
Keywords
Malting conditions, rice malt, rice beer, rice wort, mashing process, Department of Food Science and Technology
Citation
Akosim, C. Q.(2023). Evaluation of optimal malting conditions of three rice varieties for improved brewing trials (Unpublished Master's Thesis). Federal University of Technology, Owerri, Nigeria