Extract Development of sorghum Grains during Malting and Utilization of Bitter Leaf Extract for Beer Production Using Saccharomyces cerevisiae

Abstract

Aims: The aim of this study was to evaluate extract development of sorghum grains during malting and utilization of bitter leaf for production of beer using S. cerevisiae. Study Design: Randomized experimental design was used to achieve the aim of the study. Place and Duration of Study: Study was conducted at the Food and Industrial Microbiology Laboratory, Department of Microbiology, Faculty of Science, University of Port Harcourt, Choba, Rivers State between June 2021 and September 2021. Methodology: The grains were bought at a local market, steeped for 24h, germinated for 5days at 30°C and kilned at 45°C for 24h. Alpha and beta amylases were extracted from the malted sorghum and their activities were determined by measuring the maltose produced. Mashing was done using infusion method, bitter leaf extract was used in place of hops, and 500ml of the wort was pitched with 50ml inoculum of Saccharomyces cerevisiae isolated from fresh palm wine. Fermentation lasted for 14 days. Results: The results indicated that β-amylase activities were higher with a peak of 1.5mg/ml maltose as against 0.9mg/ml maltose for alpha amylase. Wort properties such as diastatic power and hot water extract were measured as 40°l and 415°l/kg respectively. The resulting beer  with bitter leave as substitute for hops gave alcohol content (%) of 3.6 and 3.4, bitterness was 100.38 IBU (International Bitterness Units) and 101.82 IBU while colour was 19.15 EBC (European Brewery Convention) and 21.45 EBC for sorghum wort having 5ml and 10ml of bitter leaf extract respectively. Conclusion: The results obtained in this study depicts sorghum malt as a source of enzymes and further reveals the brewing potentials of sorghum grains in beer production with bitter leaf as a potential substitute for hops. The bitter leaf which offered a good degree of bitterness to the beer can potentially serve as a good substitute for hops in brewing industry.