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