This study formulates a mathematical relationship correlating the degree of starch
gelatinization (DSG) of rice to the paddy moisture-electrical conductivity (EC) of
paddy water during the soaking portion of the parboiling process. DSG values of
rice were measured using differential scanning calorimetry (DSC). Paddy was parboiled
by soaking at 60, 65, 70 and 75C. At each temperature paddy samples were
selected at five different soaking times. Optimum soaking times for 60, 65, 70 and
75C were determined to be 240, 180, 120 and 80 min, respectively. Paddy moisture
(22.43–34.93%, wet basis), EC of paddy water (1.63–2.71 mS/cm) and DSG of rice
(5.38–36.90%) increased with increasing temperature and soaking time. It was
found that a linear relationship exists between DSG and EC, as well as between
DSG and moisture content during soaking. EC of paddy water correlates well with
DSG of rice during soaking. An online measurement system of paddy water EC
was manufactured and evaluated. The relationship between DSG and EC can be
utilized for quick and simple determination of DSG during soaking and eliminating
the need for conventional chemical analysis.
