Maize malting for optinum diastatic activity and riboflavin development

Abstract

The traditional processes of maize malt beverage production in Ghana were investigated and found to involve the general steps of steeping the maize grains for about 24 hours at 28- 30ᵒC and allowing germination to take place for a period of between 5 and 7 days. The resulting malt is sun-dried, milled and cooked to obtain the malt extract beverage. Although the malting procedure followed could effect considerable biochemical changes in the grains leading to the development of riboflavin and high diastatic power, analysis of the intermediate and final products showed that lack of proper attention during the germination period resulted in only a minimum degree of development of these components. The highest level of riboflavin recorded for the traditional malt was only 2.1µg/g and the diastatic activity was 30.9. An investigation was also carried out into the general changes occurring during maize malting and the factors effecting the proper development of riboflavin and diastacic activity. Biochemical changes during steeping and germination were found to include the production of various hydrolytic enzymes which catalyse metabolic activities to effect changes in the proximate composition of the grains. The most profound changes during germination occurred in the carbohydrates in which a progressive decrease in the starch content with a corresponding increase in the sugars was observed. There was also a considerable development of riboflavin and diastatic activity. Malting temperature, moisture and period of germination were found to be the main factors affecting proper developments of riboflavin and diastatic power. Optimum development was obtained in grains soaked for 24 hours and allowed to germinate for a period of 4 - 5 days at 28-30ᵒC with a constant daily sprinkling of water. Analysis of maize malt produced by this procedure shoved a four-fold riboflavin development (from 1.2 to 4.8 ug/g on Dry weight Basis) and an increase of diastatic power from 12.4 to 54.7°