Optimizing extract recovery from sorghum using combinations of exogenous crude amylase and pullulanase isolated from yeast strains from cassava mill factory

Abstract

Crude enzyme extracts of yeasts isolated from a cassava mill factory were utilized in optimizing extract recovery from sorghum or malted sorghum. Microbial enzymes are known to be very beneficial in industrial processes due to various advantages derived from them. Micro-organisms multiply very rapidly and produce diverse enzymes during the process. Such micro-organisms with potential to produce industrial crude enzymes abound in many natural environments. This study examined the performance of crude enzyme extracts (pullulanase and amylase) from yeasts strains (SP40 and SS12) isolated from a cassava mill factory. The crude enzyme extracts were used in mashing grain sorghum and malted sorghum using various enzyme combinations to study their effects on quality of wort specific gravity (SG), reducing sugars (RS) and free amino nitrogen (FAN). The decantation mashing process which protected the enzymes and gelatinized sorghum starch was more effective in producing wort of higher SG, RS and FAN products. Control enzyme (lower doses) gave wort SG of 1.034 (infusion mashing) and 1.056 (decantation mashing). Test enzymes (lower doses) also gave good wort SG of 1.018 (infusion mashing) and 1.034 (decantation mashing). The activities of pullulanase and amylase from SP40 and SS12 were similar because both microorganisms produced mainly starch hydrolysing enzymes. From this study, the crude enzymes compared well with commercial enzymes in using lower doses of the crude enzyme extract to produce wort of higher SG, RS and FAN products and this will save costs for the industry. The mashing regime is also an important factor to consider.