This study investigated the antioxidant content and activity of phenolic acids, anthocyanins, α-tocopherol and γ-oryzanol in pigmented rice (black and red rice) brans. After methanolic extraction, the DPPH free radical scavenging activity and antioxidant activity were measured. The pigmented rice bran extract had a greater reducing power than a normal rice bran extract from a long grain white rice. All bran extracts were highly effective in inhibiting linoleic acid peroxidation (60-85%). High-performance liquid chromatography (HPLC) analysis of antioxidants in rice bran found that γ-oryzanol (39-63%) and phenolic acids (33-43%) were the major antioxidants in all bran samples, and black rice bran also contained anthocyanins 18-26%. HPLC analysis of anthocyanins showed that pigmented bran was rich in cyanidin-3-glucoside (58-95%). Ferulic acid was the dominant phenolic acid in the rice bran samples. Black rice bran contained gallic, hydroxybenzoic, and protocatechuic acids in higher contents than red rice bran and normal rice bran. Furthermore, the addition of 5% black rice bran to wheat flour used for making bread produced a marked increase in the free radical scavenging and antioxidant activity compared to a control bread.

No abstract

Resistance to breakage is a desirable trait of the rice kernel. Many factors, such as the genetics of the cultivar, the plant growth environment and the conditions of the milling process, will affect kernel breakage. Although many papers have discussed the factors that may affect and improve rice milling quality, few have related the grain‐filling process to head rice, the unbroken polished kernels obtained after milling. The objectives of this paper were: (i) to characterize the interrelationships amongst grain filling and grain structural characteristics; (ii) to determine whether the grain‐filling process and grain characteristics affect head rice, and (iii) to suggest a pathway through which grain characteristics can influence head rice recovery. An analysis of the interrelationships amongst all grain characteristics suggested that variables of grain structure (size, volume and per cent hull) have a decisive influence on the grain‐filling process (rate and duration of grain filling). The grain‐filling process will affect final grain traits such as weight and density, which in turn will have a direct impact on head rice. In addition, non‐uniformity, whether expressed in terms of variable grain size and shape or grain filling and maturity, has a detrimental effect on rice milling quality. The implication of these findings is that rice breeders need to pay more attention to selecting plant types that have a high degree of uniformity of grain characteristics on the panicle, and to those traits (such as greater grain size, weight and density) that have a positive impact on yield and milling quality.

Rice(Oryza sativa L.) milling quality is a complex trait and influenced by many factors including the uniformity of grain filling and other grain characteristics. Although much is known concerning genotypic differences in rate and duration of grain filling, quantitative information on uniformity or non‐uniformity of grain filling and kernel characteristics on the panicle is lacking. This study investigated and compared the degree of non‐uniformity of grain filling among 6 rice cultivars of different grain types, maturities, and the plant characteristics that may influence the uniformity of grain filling. Models of grain growth and rate of growth were developed for grains on the upper, middle and lower parts of the panicle. Non‐uniformity of grain filling parameters (duration and rate of grain filling, maximum grain weight) were estimated and compared among cultivars of different grain types and maturities. Results showed that, in general, grain size and rate of filling decrease from upper part to the lower part of the panicle. The ranges among grain growth curves from the upper, middle and lower parts of the panicle of the very early, and early maturing cultivars were greater than those of intermediate and late maturing cultivars. However, non‐uniformity of grain filling is not necessarily a function of maturity. Plant and grain characteristics such as even distribution of grain size, high grain filling rate between 10–15 days after heading, and optimum weight ratio of panicle to above‐ground leaf and stem matter may be selected for by breeders to improve the uniformity of grain filling, independent of maturity. Zusammenfassung Uniformität der Rispenentwicklung von Reiskultivaren mit unterschiedlichen Rei‐fezeiten Die Reis (Oryza sativa L.)‐mahlqualität ist eine komplexe Eigenschaft und wird von zahlreichen Faktoren, einschließilich der Einheitlichkeit der Kornfüllung und anderer Korneigenschaften beeinßlufk. Obwohl zahlreiche Informationen bezüch genotypischer Differenzen hinsichtlich der Rate und der Dauer der Kornfüng bekannt sind, besteht ein Mangel an Informationen hinsichtlich der Einheitlich‐keit oder Uneinheitlichkeit der Kornfüng und von Korneigenschaften der Rispe. Die vorliegende Untersuchung vergleicht den Grad der Uneinheitlichkeit der Kornfüllung von sechs Reiskultivaren unterschiedlichen Korntyps, unterschiedlicher Reife und unterschiedlicher Pflanzeneigenschaften, die Einflufß auf die Einheitlichkeit der Kornfüllung nehmen können. Modelle für Kornwachstum und Wachstumsrate wurden für Körner des oberen, mittleren und unteren Abschnitts der Rispe entwickelt. Uneinheitlichkeit der Kornfüllung (Dauer und Rate der Füllung sowie maxi‐males Korngewicht) wurden geschätzt und mitden Kultivaren unterschiedlichen Korntyps und unterschiedlicher Reife verglichen. Die Ergebnisse zeigen, daß die Korngröße und Kornfüllungsrate grundsätzlich vom oberen zum unteren Teils der Rispe sehr früher und früher Kultivare waren größer als diejenigen der Kultivare mittlerer und später Reife. Allerdings ist Uneinheit...