Changes in the Activities of Alpha and Gluco-amylases during Malting of Some Improved Nigerian Sorghum Varieties

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Chukwudi I. Nnamchi
Chukwunweike O. Okoye
Arinze L. Ezugwu


In this study changes in the alpha and glucoamylase activities of four different improved sorghum varieties were monitored over a 96-hour malting time to determine how the expression of the enzymes were affected by malting. Preliminary tests showed that SK5912 had the highest weight of 40 g/1000 grains and lowest malting loss of about 13%, while KSV 8 followed a weight of 36 g/1000 grains and the most malting loss of 22.6%. Enzyme results showed that the different sorghum varieties differed in their expression of the two of them across different malting regimes. However, all the varieties showed much higher expressions of glucoamylase than α-amylase at all the malting regime. Glucoamylase consistently showed its highest activities of over 71 U/ml across the four sorghum varieties after the first day of germination with variety SRNA giving the highest value slightly above 72 U/ml. The least glucoamylase activities were also given consistently across the four varieties by the unmalted raw grain. The highest α-amylase activities were generally shown across the four varieties after the third day of germination, with variety KSV 8 showing the highest value of about 14 U/ml. The control also gave the least α-amylase activities across all varieties with KSV8 giving the least. Considering the many important and multi-faceted roles that amylases are nowadays known to perform, the study of their expression dynamics in different plants and processes, one of which we report here, could help further the understanding of their characteristics and thus facilitate their maximal utilization.

Alpha amylase, beta amylase, sorghum, grains, cereals, malting.

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Nnamchi, C. I., O. Okoye, C., & Ezugwu, A. L. (2020). Changes in the Activities of Alpha and Gluco-amylases during Malting of Some Improved Nigerian Sorghum Varieties. Journal of Scientific Research and Reports, 25(6), 1-8.
Original Research Article


Briggs DE. Malt and Malting, First Ed. Blackie Academic and Professional, London; 1998.

Ayenor GS, Ocloo FCK. Physicochemical changes and diastase activity associated with germinating paddy rice (PSB. Rc 34). African Journal of food Science. 2007;1: 037-041.

Palmer GH. Cereals in malting and brewing, in Cereal Science and Technology (Palmer, G. H. Ed.), Aberdeen University Press, Aberdeen. 1989;61–242.

Oyewole OI, Agboola FK. Comparative studies on properties of amylases extracted from kilned and unkilned malted sorghum and corn. International Journal for Biotechnology and Molecular Biology Research. 2011;2(9):46-149.

Manners DJ, Marshall JJ. Studies on carbohydrate metabolizing enzymes. Part XXIII. The ß-glucanase system of malted barley. J. Instit. Brewing. 1969;75:550-561.

Alli AL, Ogbonna CL, Rahman AT. Hydrolysis of certain Nigerian cereal starches using crude fungal amylase. Nig. J. Biotech. 1998;9:2436.

Nnamchi CI, Okolo BN, Moneke AN. Grain and malt quality properties of some improved Nigerian sorghum varieties. J Inst Brew. 2014;120:353–359.

Agu RC, Palmer GH. A reassessment of sorghum for larger beer brewing. Bioresource Technology. 1998;66:253-261.

Adejumo AL, Agboola FK, Layokun SK. Hydrolysis of maize starch using amylolytic enzymes extracted from sorghum malt. Int. J. Biol. Chem. Sci. 2009;3(5):1030- 1041.

Bamforth CW. New brewing technologies: Setting the scene In: Brewing Bamforth CW ed. Cambridge, Woodhead Publishing Limited. 2006;3.

Taylor JRN, Dlamini BC, Kruger J. 125th Anniversary review: The science of the tropical cereals sorghum, maize and rice in relation to lager beer brewing. 2013;119:1–14.

Ogbonna AC, Obi SKC, Okolo BN. Protein modification in malting sorghum. World Journal of Microbiology and Biotechnology. 2003;19:495-503.

Institute of Brewing. Recommended methods of analysis. London; 1989.

Palmer GH. Cereals in malting and brewing. In: Cereal Science and Technology, ed. Palmer GH. Aberdeen: Aberdeen University Press. 1989;61– 242.

Novellie L. Kaffir corn malting and brewing studies XI. Effect of malting conditions on the diastatic power of kaffir corn malts. Journal of the Science of Food and Agriculture. 1962;13:115–120.

Okon EU, Uwaifo AO. Evaluation of malting sorghum I: The malting potentials of Nigerian varieties of sorghum. Brewer’s Digest. 1985;60:24-29.

Briggs DE, Hough JS, Stevens R, Young TW. Malting and Brewing Science (Malt and sweet wort). Vol 1. Chapman and Hall, Ltd, USA; 1981.

Ogu EO, Odibo FJC, Agu RC, Palmer GH. Quality assessment of different sorghum varieties for their brewing potential. Journal of the Institute of Brewing. 2006;112:117– 121.

Bekele A, Bultosa G, Belete K. The effect of germination time on malt quality of six sorghum (Sorghum bicolor) varieties grown at Melkassa Ethiopia. Journal of the Institute of Brewing. 2012;118:76–81.

Aisien AO, Muts GCJ. Micro-scale malting and brewing studies of some sorghum varieties. Journal of the Institute of Brewing. 1987;93:328–331.

Daiber KH, Taylor JRN. Opaque beers. In: Sorghum and the Millets: Chemistry and Technology. (D.A.V. Dendy ed.), American Association of Cereal Chemists, St. Paul. 1995;299-323.

French BJ, McRuer GR. Malt quality as affected by various steep aeration regimes. MBAA Technical Quarterly. 1990;27:10– 14.

Dewar J, Taylor JRN, Berjak P. Determination of improved steeping conditions for sorghum malting. Journal of Cereal Science. 1997;26:129–136.

Nnamchi CI, Okolo BN, Moneke AN, Nwanguma BC. Effect of different steeping conditions on the peroxidase activities of some improved sorghum varieties. Bio Research. 2012;11:819–824.

Nnamchi CI, Okolo BN, Moneke AN, Nwanguma BC. Changes in the activities of peroxidases during different stages of sorghum malting. Int. J. Adv. Res. 2013; 1(7):44-58.

EtokAkpan OU, Palmer GH. Comparative studies of the development of endosperm-degrading enzymes in malting sorghum and barley. World J. Microbiol. Biotechnol. 1990;6:408-417.