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Juliano B.O.,Philippine Rice Research Institute Los Banos | Tuano A.P.P.,Philippine Rice Research Institute Los Banos | Monteroso D.N.,Philippine Rice Research Institute Los Banos | Aoki N.,Japan National Agriculture and Food Research Organization | And 3 more authors.
Cereal Foods World | Year: 2012

An improved iodine colorimetric method based on ammoniumbuffered pH 9 solution (NH4Cl-KI) is reported. The method produces blue color and measures apparent amylose contents (AC) of nonwaxy rice, using potato amylose standard, and results in values similar to those observed when using differential scanning calorimetry (DSC), based on the exotherm of amylose-lipid complex formation, which has no amylopectin and lipid interference. Using the iodine colorimetric method, waxy rice had AC values of 2-3%, while undefatted, milled rice samples had AC values similar to those observed using the DSC method, probably because interference from amylopectin-iodine and amylose-lipid complexes cancelled each other. Using the iodine-NH4I method, AC values for five nonwaxy rice varieties were identical to DSC values, while AC values for the iodine colorimetric method with acetate buffer were not identical to DSC values when amylose alone was used as the standard. Using an amylose-waxy rice standard, the ammonium buffer method resulted in 4 nonwaxy rice varieties with AC values identical to DSC values. Iodine-NH4I resulted in 14 AC values identical to DSC values, and AACC International Approved Method 61-03.01 resulted in 7 of 16 rice samples with AC values identical to DSC values. AC determined using DSC and iodine colorimetry, both based on amylose helical complexes, were higher than AC (true amylose plus long-chain amylopectin) determined using high-performance size-exclusion chromatography (HPSEC) of debranched starch and amylopectin. The ammonium buffer method produced a blue color, AC values for nonwaxy rice that were similar to those for the DSC method, and allowed use of undefatted rice samples and an amylose standard alone without waxy rice (amylopectin). © 2012 AACC International, Inc. Source

Tuano A.P.P.,University of the Philippines at Los Banos | Xu Z.,Louisiana State University | Castillo M.B.,University of the Philippines at Los Banos | Mamaril C.P.,University of the Philippines at Los Banos | And 4 more authors.
Philippine Agricultural Scientist | Year: 2011

Application of organic and inorganic fertilizer and pesticides to the rice crop had no consistent effect on the content of α-tocopherol (vitamin E), α-tocotrienol, γ-tocopherol, γ-tocotrienol, total tocols and γ-oryzanol of NSIC Rc146 and NSIC Rc160 brown rice and NSIC Rc146 milled rice. Brown rice had more tocols and γ-oryzanol than milled rice. Total phenolics of NSIC Rc160 brown rice were lower in the control and organic rice than in rice treated with inorganic fertilizer and pesticide. The 1 st and 2 nd crops of organic milled rice had lower protein content than milled rice treated with inorganic fertilizer, and subsequently tended to have softer Instron cooked rice hardness value and higher Rapid Visco-Analyser (RVA) peak viscosity. Milling quality, color, apparent amylose content and alkali spreading value of rice in the various treatments were similar. Source

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