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 ?-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.
ABSTRACT
Endoglucanase (EC3.2.1.4) from sorghum (S. bi-color) and millet (Pennisetum typhoides & Digitaria exilis) malts were purified to homogeneity through the methods of ammonium sulphate precipitation and gel filtration. Molecular mass of 35 KDa and 41 KDa were determined by SDS-PAGE. The purified enzymes catalyzed the hydrolysis of carboxy-methylcellulose with optimum activity at pH of 4.8, 5.0, 6.0, and temperature of 60ºC, 60ºC and 70ºC for Digitaria exilis, S. bi-color and Pennisetum typhoides respectively. More than 90% activity was retained in S. bi-color and Pennisetum typhoides and 73% activity in Digitaria exilis after 1.0 hour pre-incubation at 60ºC. Km values of 0.11, 0.09, 0.20 mM and Vmax 17.53, 15.0 and 11.10 U/mg/min were obtained for S. bi-color, Pennisetum typhoides and Digitaria exilis respectively. Co2+ inhibited endoglucanase activity whereas Ca2+, Ba2+, and Zn2+ enhanced enzyme activity. The enzyme was inactivated by glucose, a major end product of cellulose hydrolysis. Results indicate that endoglucanase of S. bi-color and Pennisetum typhoides are more suitable for malting and a blend of the two will produce high quality malt.
ABSTRACT
African breadfruit seeds have the potentials as carbon source for ethanol production with a carbohydrate value of 72.19%. On malting the seeds at 28±2oC for 9 days it yielded a 96% germination capacity and total malting loss of 25.70%. Grain dormancy was broken by the second day of malting. Malted breadfruit seeds were ground and defatted to 0.78% fat content. Full fat breadfruit and defatted breadfruit flours were used as adjuncts in the ratio of 3:5 (adjuncts: barley). Fermentation parameters such as wort fermentable sugar, specific gravity, extract yield and ethanol were measured over the 9 days of fermentation. Extract yields were 12.59, 9.66 and 11.23% while ethanol production was 5.79, 6.39 and 6.10% for wort from defatted breadfruit, full fat breadfruit and maize, respectively.
ABSTRACT
In this work the α and β-amylase enzymes were obtained from maize (Zea mays) malt and were biochemistry characterized. A germination study to obtain the maize malt with good amylase activity was made. The maize seeds were germinated in laboratory and the enzymatic activity was measured daily. Activity dependence to germination time were fitted to an exponential model (A=A0eµt), which showed that the behaviour of enzymatic activity in the germination process was similar to the growth of the microorganism. Its model could be applied to describe the mechanism of α-amylase production for each maize varieties and others cereals. Maize malt characterization showed that α and β-amylase had optimal pH between 4-6.5, optimal temperature 50 and 90ºC, and molecular weight of 67.4 and 47.5kDa, respectively. This work contributed with the advances in biotechnology generating of conditions for application of a new and of low price amylases source.
Neste trabalho as enzimas α e β-amilases foram obtidas de malte de milho e depois foram caracterizadas bioquimicamente. Um estudo da germinação foi feito para obtenção do malte com boa atividade amilásica. A germinação ocorreu em escala laboratorial e a atividade enzimática foi medida diariamente. Um modelo exponencial do tipo A=A0eµt foi ajustado a dependência do tempo de germinação com a atividade, mostrando que o comportamento da atividade enzimática no processo de germinação é semelhante ao crescimento de microorganismos. Este modelo pode ser aplicado para descrever o mecanismo de produção da α-amilase para cada variedade de milho e de outros cereais. A caracterização do malte de milho mostrou que as α e β-amilase têm pH ótimo entre 4,0-6,5, temperatura ótima de 50 e 90ºC, e massa molar de 67,4 e 47,5 kDa, respectivamente. Este trabalho contribuiu com os avanços da biotecnologia gerando condições de emprego de uma nova e barata fonte de amilases.