ENZYMES ACTIVITIES OF PRE-GELATINIZED STARCH ADJUNCTS AND MALTS AT DIFFERENT TEMPERATURES (50, 60, 70, AND 80 °C)

Studies were carried out on the enzyme activities of pre-gelatinized starch adjunct and malts at different temperatures. The sorghum (red variety) was purchased, sorted, analysed (grain analysis), malted, analysed again (malt analysis), and milled. A total of 10g of the unmalted sorghum flour (adjunct) were weighed into 4 different 500ml conical flasks, distilled water (360ml) was added to the flasks and the mixtures were pre-gelatinized at different temperatures viz: 50, 60, 70 and 800C after which 40g of malted sorghum grist were added to each conical flask with 1ml of exogenous enzymes (thermamyl, fungamyl, neutrase and amyloglucosidase). The samples were properly shaken before the infusion mashing technique was used to obtain worts of various concentrations. After mashing, the resulting worts were analysed, followed by worts boiling with hops for 1h 30mins. The boiled worts were cooled with subsequent pitching of yeast strain Saccharomyces cerevisiae, before primary fermentation, which lasted 7 days, and secondary fermentation for another 14 days. The results of wort analysis showed original gravity ranging from 1030-1036 °r, sugar level (7.55-9.02) °Brix, pH (5.49-5.62), and viscosity (1.04-1.05)CP at room temperature. The beer analysis showed a specific gravity range of (1001-1002) or, sugar level (0.26-0.52) °Brix, pH (3.80-3.89), % alcohol (3.6-4.5)%v/v at the temperature of 24°C. The results from sensory evaluation showed no significant differences among the samples based on the parameters tested at the P≤0.05 level of significance. The study concluded that, with proper processing and enzyme supplementation, sorghum can be effectively used as a malt or adjunct in beer production, offering a cost-effective and locally available alternative to barley in African brewing industries. Pre-gelatinization at 70°C according to this study yielded the best result and, as such, is the most suitable temperature for the gelatinization of sorghum starch.