MALTING PROPERTIES OF PEARL MILLET, PENNISETUM AMERICANUM, AND ITS EFFECTS ON BREWERS' YEAST

No Thumbnail Available
Date
1997-07
Authors
DAMISA, DURO
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Pearl millet, Pennisetum americanum (L). FV.19 Cultivar was used in this study involving two malting cycles, (2 - clay) and (3-day) and five kilning temperatures; (40°, 45°, 50°, 55° and 60 c). Malts were prepared from this cultivar by steeping for 24 hours, germinating for either 2 - days or 3 days and kilning at the live temperatures. Analysis were made for the malting loss, mall yield, diastatic power, cold - and hot- water extracts of the ground malts. Worts derived from each malt by the infusion method of mashing were fermented by batch method of fermentation for nine days using the brewers' yeast, Saccharomyces uvarum, Effect of the fermenting wort on the brewers' yeast were studied and the yeast flocculence determined Products of the unconverted starch in the fermented worts were analysed for all the worts. Results indicate that germination period has remarkable effect on the quality of malt produced as the 3-day regime malt gave better malt qualities than the 2-day regime malt although the cold-and hot-water extract, and diastatic power assessment of the malt were far inferior to those of commercial barley malt. Prolonged malting gave low malt yield. Malt yield was found to be high as only 10 to 18 percent of initial weight of grains were lost in both cycles. Steeping the grain at room temperature lor 24 hours is conducive before malting; malting for 3-days, and thereafter kilning at 50 c for 24 hours was found to be the best for producing good malt Fermented won prepared from the malt indicated that amylodextrins and erythrodextrins are largely the products of the unconverted starch in the wort for the 2-day and 3-day regime malts respectively Yeast floccculence was satisfactory ( 70 % ) and a decline in the fermentable sugars promoted flocculation Yeast viability was maintained for the three pitching cycles although the generation time was high (.32 - 40 hours) with low number of generations ( 5- 8 ) and growth rate (4.2 x K) 4-5.1 x 10-4 ). Bud formation was observed nine hours into the initiation of fermentation and slowed down towards the termination of fermentation, with cells looking elongated with irregular buds The pH of the wort was satisfactory (3.8), but the alcohol percent by volume obtained was low (l.3%V/V). These results show that malting and kilning of millet have no adverse effects on brewers' yeast and as such could provide a source of raw materials in the brewing industry and also as substrate for single cell protein production The millet mall may be formulated to provide a good source of malt extract for microbiological media.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE (M .Sc) in MICROBIOLOGY Department of Microbiology Faculty of Science Ahmatlu Bello University Zaria, Nigeria July, 1997.
Keywords
MALTING,, PEARL MILLET,, PENNISETUM,, AMERICANUM,, BREWERS' YEAST.
Citation
Collections