banner 24. Influence of added commercial enzyme preparations and mashing temperature on extract recovery of laboratory malted Nigerian grown pearl millet and wheat

C. I. NNAMCHI (1), R. Agu (2), A. N. Moneke (1), F. C. Odibo (3), B. C. Nwanguma (1), B. N. Okolo (1); (1) University of Nigeria, Nsukka, Nsukka, Nigeria; (2) The Scotch Whisky Research Institute/University of Nigeria, Nsukka, Riccarton/Nsukka, Nigeria; (3) Nnamdi Azikiwe University, University of Nigeria, Nsukka, Awka/Nsukka, Nigeria

Technical Session 7 - Malt and Grain
Tuesday, June 16
8:30–10:15 a.m.
Fiesta 3,4,6,8

The aim of this work was to demonstrate how different commercial enzymes and mashing temperatures of 65°C and 85°C influenced extract recovery during infusion mashing of Nigerian-grown pearl millet and wheat malts. Additionally, the effects of differences in the starch granules of the two cereal types on extract recovery were studied. Results obtained showed that wheat grown in Nigeria contained high proportions of very large-sized starch granules and reasonable amounts of small starch granules while millet contained only small granules. When mashed at 65°C, both cereal malts produced extract yields at similar levels, while mashing at 85°C increased their extracts beyond twofold. The addition of commercial enzymes during mashing of malts from both crops produced different effects. Added amylases increased extract yields of both cereals many fold at the two mashing temperatures. Added β-glucanase enzyme was more effective on millet malt than on wheat malt at 65°C despite both cereals having similar β-glucan contents. Added xylanase was more effective on wheat malt than on millet malt at both infusion mashing temperatures. Added combined β-glucanase/xylanase enzyme was more effective on wheat malt than on millet malt especially at the mashing temperature of 85°C. However, the individual enzymes produced higher levels of extracts than their combinations, a significant fact considering the immensely high cost of enzymes. Thus, the correct and proper choice of individual enzymes such as α-amylase, β-glucanase, and xylanase rather than their combinations should produce higher extracts from the cereals. These results highlight the complex grain physiology of cereals and therefore the need for continuous research on them. In this work, α-amylase added during infusion mashing of wheat malt at 65°C gave the highest extract of 304 L°/kg (as is). Similarly, β-glucanase enzyme added during infusion mashing of millet malt at 65°C gave highest extract of 304 L°/kg (as is).

Nnamchi Chukwudi Innocent was born in Enugu, Nigeria. He obtained his B.S. degree in microbiology/biochemistry (combined honors) in 1998 and a master’s degree in environmental microbiology in 2004. In 2014, he obtained a Ph.D. degree in industrial microbiology and biotechnology. His degrees all were obtained from the Department of Microbiology, University of Nigeria, Nsukka. In 2006, Chukwudi joined the Department of Microbiology, University of Nigeria, Nsukka, as an assistant lecturer. He is currently a senior lecturer in the same department. He was a visiting research fellow to the University of Leicester, England, from October 2010 to September, 2011, where he worked on the purification and characterization of peroxidases from Nigerian sorghum varieties. His current research interests include malting- and brewing-related work with using sorghum, millet, maize, wheat, and barley. Such work often includes the assessment of how key enzymes affect brewing with these grains. He is a member of the Nigerian Society of Microbiology (NSM), the American Society of Microbiology (ASM), the Society for Applied Microbiology (SFAM), and the New York Academy of Science (NYAS), among others. He has also won many awards and grants and traveled for conferences in different areas of applied microbiology in different parts of the world.