EFFECTS OF MALTING CONDITIONS TO QUALITY OF GERMINATED RED SORGHUM

Abstract

Sorghum, one of the most popular cereals in the world, can be used directly or in malted and/or fermented form in the preparation of several traditional foods. The aim of this study was to investigate the effects of malting conditions to quality germination of red sorghum in order to select the malted sorghum for beverage production. Twenty malts types originated from red sorghum (Sorghum bicolor L. Moench) were produced under different experimental conditions: steeping (30 °C for 15 - 44 h with and without aeration), germination (30 °C, 98 % relative humidity, 45 - 72 h) and drying or lyophilisation. Dry matter loss, production of sugar, α and β-amylase activities were determined. The obtained results showed the distribution of dry matter loss during malting: steeping (2.2 - 4.0 %), germination (3.7 - 6.5 %), drying (1 %) and degerming (4.3 - 7.5 %). The starch was slightly hydrolysed (2.5 %) for producing soluble sugars: maltose (2.9 - 4.0 %) and glucose (1.7 - 3.6 %). Any organic acids production during the malting was detected. The obtained malted sorghum contained high α-amylase activity but a low level of β-amylase. The highest α- and β-amylase activities were 173.1 U.gms-1 and 3.4 U.gms-1, respectively. These results were obtained for steeping 44 h with aeration, germinated 45 h and lyophilised sorghum. The amylase activities were positively correlated with the water content of grain at the end of steeping.