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Title: Comparative Evaluation of Malting Properties and Processing Conditions on Enzymatic Activity of Ten Rice Varieties
Authors: Ngwenkoma, Nienu Petra
Issue Date: 11-Jun-2011
Abstract: Diastatic power or activity gives a measure of the saccharifying power of enzymes in prepared malt. There are about 80,000 varieties of rice that exist and new varieties are being developed through continuous plant breeding research. Among these new varieties are some whose malts possess beneficial qualities such as good diastatic activity for the sugar, confectionery, pharmaceutical and brewing industries. Hence, the need to explore these varieties as a cheap source of glucose.Themalting parameters of the ten rice varieties namely; Wita 7, Digang, Bourke’189, ITA 320, Jasmine’85, China, ITA 324, Viwornor, China and Sikamo were studied. Different conditions (pH, temperature, substrate conc. and time) were also examined to assess their effects on enzyme activity in ten varieties of malted rice. The effect of pH (2-9), temperature (10-60oC), substrate concentration (0.5-3.0w/v) and time (5-15mins) on the enzyme activity was studied using correlation whiles the optimum conditions for all Rice Malt Extract was determined using principal component analysis and response surface plots. The out-of-steep -moisture content ranged between 30.07% (Digang) and 35.26% (Bourke’189). With the exception of Sikamo (steeping loss of 2.41%), the other varieties showed steeping losses of greater than 3% after grain steeping. Germination energy of >80 % was obtained for each variety and this signified their viability.The findings show that the different varieties had good malting properties. Among all the conditions varied, temperature had the most significant effect on enzyme activity. An increase in temperature increased enzyme activity of the varieties and vice versa. The optimum conditions determined for diastatic activity of the rice malts werepH of 5.5, substrate concentration of 3.0%w/v, temperature of 60ºC and time of 15minutes.Viwornor,China and Wita 7 varietieswere found to produce the highestdiastatic power among the ten rice varieties.
Description: A Thesis Submitted as a Partial Fulfillment of the Requirement for the Award of Master of Science Degree in Food Science and Technology,2011
URI: http://hdl.handle.net/123456789/4734
Appears in Collections:College of Science

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