Effect of Parboiling Treatment on the Milling Quality of Selected Rice Varieties

Abstract

Based on previous results indicating excessive milling loss inherent in rice  milling process in Ethiopia, a study was conducted to evaluate the effects of  parboiling treatment on three released (Gumara, Kokit, and Tigabe) and one  local (X-Jigna) rice varieties. Parboiled and un-parboiled rice samples were  milled using small and portable Rice Whitener (SRW). The result has  indicated that the response for Parboiling is variety specific. But, in general,  parboiling resulted in improved milling quality in most of the studied  varieties. An overall increase in Milling yield (from 62.70 to 65.83%),  milling recovery (from 79.50 to 83.97%) and whole grain yield (from 27.83  to 37.68%), was observed while milling loss has reduced (from 16.50 to  12.50%) by this treatment. Likewise, parboiling reduced machine throughput  and output. Milling qualities of Gumara and Tigabe and, to some extent,  Kokit varieties had been improver and that of X-Jigna declined when milled  parboiled. Tigabe and Kokit had shown more or less similar milling  properties when milled raw but Tigabe had shown better milling qualities  when milled after parboiling. Thus, from the overall results of the research it  become clear that milling qualities of the three varieties (Gumara,  Tigabe,and Kokit) can be improved by parboiling. But parboiling had  undesirable consequences on milling qualities of X-Jigna variety. It is  therefore recommended that, along with improving the design of SRW  machine, use of parboiling for selected varieties should be encouraged.  Besides, under raw paddy milling conditions varieties with better milling  quality as X-Jigna should preferably be promoted than lower milling quality  Gumara variety. Improving the milling quality of Gumara and Tigabe by  parboiling may also be useful.