Black rice

About: Black rice is a research topic. Over the lifetime, 2548 publications have been published within this topic receiving 20840 citations. The topic is also known as: purple rice.

Quantification of carotenoid and flavonoid components in brans of some thai black rice cultivars using supercritical fluid extraction and high-performance liquid chromatography-mass spectrometry

Abstract: A method employing supercritical fluid extraction (SFE) followed by high-performance liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) was developed and used for quantification of the antioxidants in groups of carotenoids and flavonoids in the bran of four Thai black rice cultivars: Kao Hom Nin BD, Kao Hom Nin BT, Kao Hom Nin BT no. 3 and 1000–11–2–26. Trans-β-carotene, quercetin and isorhamnetin were identified in the crude yellow extracts obtained from SFE using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Their contents in the black rice bran samples were determined using LC-ESI-MS operated in the selected ion monitoring (SIM) mode. The response of the mass spectrometric detection in the SIM mode was linear, within the range of 1.00–40.00 µg/mL (r2 = 0.9997), 0.25–2.00 µg/mL (r2 = 0.9987) and 0.25–2.00 µg/mL (r2 = 0.9982); the limit of detection was at 0.10, 0.15 and 0.15 µg/mL, and the limit of quantitation was 0.80 g of rice bran for trans-β-carotene and 0.60 g of rice bran for both quercetin and isorhamnetin. Method precisions in terms of intraday and inter-day coefficients of variation were under 3.67% (relative standard deviation). The accuracy of the method estimated by determination of known concentrations of trans-β-carotene in the certified reference material, Standard Reference Material 3276, was found to range from 92 to 101%. Trans-β-carotene, quercetin and isorhamnetin were present in the bran of all black rice cultivars within the range of 33.60–41, 1.08–2.85 and 0.05–0.83 µg/g, respectively. PRACTICAL APPLICATIONS Production and accumulation of trans-β-carotene, quercetin and isorhamnetin in the bran of black rice revealed in this study imply that more attention should be paid to the analysis for screening black rice that has high contents of these bioactive phytochemicals, especially those obtained in rice-breeding programs. The developed supercritical fluid extraction and liquid chromatography-mass spectrometry method for quantification of β-carotene, quercetin and isorhamnetin in black rice bran samples proved to be selective, precise, linear and sensitive, and can efficiently be employed for such analytical purposes. Additionally, extraction of carotene components by supercritical CO2 prior to LC-MS analysis not only makes the total analysis time much shorter than that of the conventional extraction methods but also eliminates a sample clean-up step, thus offering a clean analytical procedure.

흑미 미강 쿠키의 항산화활성 및 품질특성

Abstract: Black rice bran powder has potential medical uses and functionality. In this study, we assessed the antioxidant activity and quality characteristics of cookies containing various concentrations (0, 1, 3, 5, 7, and 9%) of black rice bran powder. To analyze quality characteristics, proximate composition, fatty acid composition, amino acid composition, bulk density and pH of the dough, spread factor, loss rate, leavening rate, color, texture profile analysis, and sensory evaluations were measured. Black rice bran cookies (7%) contained more crude protein (10.67±0.33%) compared to control (5.84±0.06%). The total unsaturated fatty acid contents of the control and 7% black rice bran cookies were 30.44 and 30.81%, respectively. The amino acid content of 7% black rice bran cookie was higher than that of control. Bulk density of the dough, moisture, spread factor, total polyphenol content, and DPPH free radical scavenging activity of the cookies significantly increased with increasing content of black rice bran powder, whereas pH of the dough, loss rate, leavening rate, and L values of the cookies decreased. Additionally, consumer acceptability scores for the 7% black rice bran cookie group ranked significantly higher than those of the other groups in terms of appearance, taste, flavor, texture, and overall preference. Taken together, the results of this study suggest that black rice bran powder is an effective ingredient for increasing the consumer acceptability and functionality of cookies.

Synthesis and characterization of antibacterial silver nanoparticle-impregnated rice husks and rice husk ash.

Abstract: Silver nanoparticle (AgNP)-impregnated rice husks/rice hush ash (RHs/RHA) were successfully synthesized, and their potential application as antibacterial materials in water disinfection was investigated with particular attention given to the use of both white rice husk ash (WRHA) and black rice husk ash (BRHA) produced by the combustion of RHs as AgNP supports. AgNPs, with diameter of ∼20 nm, were anchored tightly onto RHA, with the emplacement of the AgNPs on these supports increasing the antibacterial activity of the AgNPs through diminution in the extent of nanoparticle aggregation. Ag K-edge XANES analysis revealed that AgNP-impregnated RHs/RHA are composed of both Ag(0) and Ag(I) species with the Ag(I)/Ag(0) ratio following the order WRHA (65:35) > RHs (59:41) > BRHA (7:93). Sodium thioglycolate, a strong Ag(I) ligand, significantly affected the bactericidal activities of AgNP-impregnated RHs/RHA, suggesting that Ag(I) released from AgNP-impregnated RHs/RHA plays an important role in disinfection. Th...

The genetic constitutions of complementary genes Pp and Pb determine the purple color variation in pericarps with cyanidin-3-O-glucoside depositions in black rice

Abstract: The purple pericarp color in rice was controlled by two dominant complementary genes, Pb and Pp. Crossing black rice ‘Heugnambyeo’ variants with three varieties of white pericarp rice gave a segregation ratio of 9 purple: 3 brown: 4 white. The Pp genes were segregated by homozygous PpPp alleles for the dark purple pericarps, heterozygous Pppp alleles for the medium and mixed purple pericarps, and homozygous pppp alleles for either brown or white pericarps with a 1 PpPp: 2 Pppp: 1 pppp segregation ratio, indicating that the Pp allele in rice is incompletely dominant to the recessive pp allele. Among the purple seeds, the amount of cyanidin-3-O-glucoside was higher in the dark purple seeds (Pb_PpPp) than in the medium purple seeds (Pb_Pppp). Moreover, no cyanidin-3-glucoside was detected in brown (Pb_pppp) or white pericarp seeds (pbpbpppp). These findings indicated that the level of cyanidin-3-glucoside was determined by the copy number of the Pp allele. Further genotype investigation of the F3 progeny demonstrated that the dominant Pb allele was present in either purple or brown pericarp. A 2-bp (GT) deletion from the DNA sequences of the dominant and functional Pb was found in the same DNA sequences of the recessive and non-functional pb allele. These findings suggested that the presence of at least a dominant Pb allele was an essential factor for color development in rice pericarps. In conclusion, the Pp allele in rice is incompletely dominant to the recessive pp allele; thus, the number of dominant Pp alleles determines the concentration of cyanidin-3-O-glucoside in black rice.