Abstract:
Parboiling is the hydrothermal treatment applied to the paddy grains
before milling in order to increase the milling recovery. Parboiling process consist
three stages such as soaking, steaming and drying. In this study the effects of effluent
changing interval on milling yield of two different paddy varieties were estimated. In
addition to that, the evaluation of characteristic effluent and hydro profile of paddy
also were done. Paddy varieties of Department recommended variety BG 360 and
industrial preference variety Addakari were soaked in water at ambient temperature.
Two experimental setups were designed for both varieties with changing the effluent
at each 12 hour interval and 24 hour interval within 48 hour duration. At every 6 hour
interval, effluent samples were collected for characterization. After 48 hours of
soaking, paddy grains were steamed till few of their hulls split off. It was then cooled
and sun dried until the moisture reduced up to 14%. Analytical grade de-husking and
polishing machines were used for the milling. In the milling yield analysis, Addakari
rice variety with changing the effluent at 12 hour interval resulted higher, total milled
rice yield percentage, brown rice percentage and degree of milling percentage as
73.66%, 81.77% and 90.08%, respectively. The head rice percentage was 68.26 % to
the same variety butwith changing the effluent at 24 hour interval.The rice varietyBG
360 with effluent changed at 24hr interval yielded higher hull percentage as 21.66%.
The whiteness value of BG 360 with changing the effluent at 12 hour interval was
higher than other treatment and that of other variety as 27.8%. It resulted in higher
hydration profile of BG 360 rice variety, due to the larger surface area. When
considering the effluent characteristic with different changing interval of effluent, the
treatment with time interval of 12 hour showed lesser level contaminants in the
effluent, which can be utilized for the secondary purposes like irrigation. According to
this study, it was identified that effluent changing interval, influences the milling yield,
hydration profile and physical properties of different rice varieties.
