CHARACTERISTICS OF WATER-UPTAKE OF AUSTRALIAN POLISHED BARLEY IN SHOCHU-MAKING

Characteristics of water uptake during steeping of 70% polished Austra lian barley, used as material for shochu making, were studied on 6 gra in samples. There were some similarities in water uptake curves in spi te of the differences in varieties and regions of harvest. Polished ba rley abruptly absorbed water at the same time when in contact with wat er. After 5 h the water uptake content reached 52 to 56, 54 to 59, and 58 to 63% grain wet weight at 15, 20, and 30 degrees C respectively. The relationship between water uptake and steeping time may be describ ed by the equation Y=aX(b), where Y is the water uptake (%), X is the time (min), and a and b are coefficients(l). From the data obtained wi th Schooner (South), the water uptake curve in steeping at 15 degrees C was described as y=5.50X(0.40) (r(2)=0.993). Furthermore a log-log p lot of water uptake (%) against integrated steeping temperature (IST), which was presented by the product of temperature and time, showed a very clear linear relationship, and could be represented by Y=2.047(T. t)(0.382) (r(2)-0.987). The coefficient values a and b determined the relationship of water uptake and IST on 6 samples. The values of 5 sam ples, excluding Stirling (West) were close (a=2.05 to 2.33 and b= 0.37 to 0.38), and no differences were apparent amongst these varieties an d regions. Stirling (West) with a=1.81 and b=0.40 were similar to the Japanese barley cultivar Nishinochikara (a=1.99, b=0.39). The Schooner (South) equation could generally be applied to control water uptake d uring steeping on 70% polished Australian barley supplied to our facto ry. The water uptake values from the steeping experiments were between 35.1 and 36.7% when the objective value was set at 35%.