Effect of final moisture content, cooling time and paddy variety on milling quality of rice in Kilombero district,Morogoro, Tanzania.
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Date
2014
Authors
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Publisher
Sokoine University of Agriculture
Abstract
Drying and milling of paddy are the key processes and critical post-harvest operations
influencing the quality of the milled rice. The current study was carried out to
establish the effects of three factors -final moisture content, shade-cooling time and
paddy variety on rice milling quality. Paddy was sun dried to final moisture contents
ranging from 9-15.5% (on wet basis) and shade-cooled fbr 0, 6, 12, 18, and 24 hours
at ambient temperature (27.20 - 35.10°C). Five paddy varieties, TXD 88, TXD 306,
SUP A, IRRITA 1 and IRRITA 2 were studied. The milling tests were carried out
using a laboratory rice mill. Latin square design with 5 replications (5x5 orders) was
used. Physical properties and milling quality in terms of total rice yield (TRY), head
rice yield (HRY) and whiteness index (WI) were analysed. The physical properties
differed significantly (P< 0.05) among varieties. SUPA had good size, shape and
chalkiness whereas TXD 88 had poor quality for all these parameters. IRRITA 1 and
IRRITA 2 produced higher TRY compared to other tested varieties. TXD 88 had
higlier whiteness index but lower HRY compared to other tested varieties. Final
moisture content influenced quality of the milled rice. Higher yields, which were
significantly different fbr TRY and HRY (P<0.05) were obtained at moisture content
between 9-12.5% for TRY, but between 10.5-14% for HRY. Final moisture content
had no significant effect on whiteness index. Shade-cooling time had no significant
effects on TRY, HRY and whiteness. As the chief element in fixing the value of
paddy is the amount of "head rice" (whole grains), which can be milled out of it,
therefore paddy should be dried gradually to the moisture content of about 10.5 一
14% for effective milling.
Description
Dissertation
Keywords
Paddy Grain, Rice Milling Process, Total Rice Yield, Kilombero rice