ABSTRACT
A thin layer solar drying method was compared with a traditional method (sun drying)
of paddy drying, with their effects on quality characteristics of two varieties of Iranian
rice (Kamphiroozi and Sazandegi) studied. Solar drying process was conducted in a
passive, mixed mode type solar dryer at about 50ºC for 90 minutes. In sun drying method
this process took 8-10 hours at a mean temperature of about 26ºC. Samples were milled
and polished. Quality factors including trade quality (head rice yield percent and
whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency,
aroma and flavor) as well as nutritional quality (thiamine and lysine contents) were
evaluated. For a determination of head rice yield, the percentages of de-husked and
broken kernels were determined by hand-sorting of broken kernels, the calculation being
done through the pertaining formula. Gel consistency was determined according to the
method of Cagampang et al. (the consistency of milled rice paste that has been gelatinized
by being boiled in dilute alkali and then cooled to room temperature). Amylose content
was determined through the simplified assay method of Juliano (setting standard curve
by spectrophotometer and comparing the adsorption with the sample’s). Gelatinization
temperature was estimated by the extent of alkali spreading and clearing of milled rice
soaked in 1.7% KOH for 23 hours at room temperature. Organoleptic characteristics of
cooked rice (iflavor, aroma) and apparent whiteness were judged by the
ABSTRACTA thin layer solar drying method was compared with a traditional method (sun drying)of paddy drying, with their effects on quality characteristics of two varieties of Iranianrice (Kamphiroozi and Sazandegi) studied. Solar drying process was conducted in apassive, mixed mode type solar dryer at about 50ºC for 90 minutes. In sun drying methodthis process took 8-10 hours at a mean temperature of about 26ºC. Samples were milledand polished. Quality factors including trade quality (head rice yield percent andwhiteness), cooking quality (amylose content, gelatinization temperature, gel consistency,aroma and flavor) as well as nutritional quality (thiamine and lysine contents) wereevaluated. For a determination of head rice yield, the percentages of de-husked andbroken kernels were determined by hand-sorting of broken kernels, the calculation beingdone through the pertaining formula. Gel consistency was determined according to themethod of Cagampang et al. (the consistency of milled rice paste that has been gelatinizedby being boiled in dilute alkali and then cooled to room temperature). Amylose contentwas determined through the simplified assay method of Juliano (setting standard curveby spectrophotometer and comparing the adsorption with the sample’s). Gelatinizationtemperature was estimated by the extent of alkali spreading and clearing of milled ricesoaked in 1.7% KOH for 23 hours at room temperature. Organoleptic characteristics ofcooked rice (iflavor, aroma) and apparent whiteness were judged by the
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