Black Rices Research Articles

Determination of contents and antioxidant activity of free and bound phenolics compounds and in vitro digestibility of commercial black and red rice (Oryza sativa L.) varieties

Black and red rices (Oryza sativa L.) were analysed for total flavonoids and phenolics and the HPLC profile including both free and bound phenolic fractions. Moreover, antioxidant activity and in vitro digestibility was determined. Content of flavonoids and polyphenols as well as antioxidant activity was higher in free phenolic fractions. Bound flavonoids in black rices were not significant contributors to antioxidant activity. The main free phenolics in black rices were ferulic, protocatechuic and trans-p-coumaric acids, while the major free phenolics in red rices were catechin, protocatechuic and caffeic acids. The main bound phenolics in black rices were ferulic and vanillic acids and quercetin, in red rice types, they were ferulic, syringic, trans-p-coumaric acids and quercetin. Newly, the presence of m-coumaric acid in red rices was detected. Steam cooked rices showed very high levels of organic matter digestibility, whereas red rices were significantly more digestible than black rices (p<0.05).

Variation of Functional Materials and Antioxidant Activity as Affected by Cultivation Environment in Pigmented Rice Varieties

Production of high quality pigmented rice contained with high content of anthocyanin, and polyphenol was significantly influenced by cultivation environments like transplanting date and cultivation location. This study was carried out to establish an optimum transplanting date and cultivation region to produce maximum content of anthocyanin, polyphenol and antioxidant activity of pigmented rice varieties (black, red colored). Three transplanting times (May 20, June 5, June 20) and four different sites (Miryang, Uiseong, Sangju, Bonghwa) were evaluated with five pigmented rice cultivars. Anthocyanin and total polyphenol index to average temperature during 30 days after heading (DAH) of black, red pigmented rice varieties showed that anthocyanin and total polyphenol contents were decreased by 10% and 9%, respectively, with increasing average temperature of . The optimum ripening temperature of the 30 DAH for the production of high anthocyanin and total polyphenol was 22 to for early maturity black rice, 21 to for mid-late maturity of black and red rices, respectively. On the other hand, an estimated heading date of pigmented rices in return according to the optimum ripening temperature of the 30 DAH was ranged Aug. 11 to 17 for early maturity black rice, Aug. 25 for mid-late maturity black, red rice variety in Jecheon, Aug. 27 to Sep. 2 for early maturity type, Sep. 3 to 6 for mid-late type in Daegu. It seemed that Jecheon, Boeun, Mungyeong, and Yeongju were optimum regions for cultivation of pigmented rices. The estimated sowing date of pigmented rices for high anthocyanin and total polyphenol production based on the optimum heading date was May 18 to 26 for early maturity black rice variety, April 11 for mid-late black, red variety in Jecheon, May 23 to 28 for early type, April 9 to 26 for mid-late type in Boeun, respectively.

Profiles of Fatty Acid Distribution of Different Acyl Lipids from Red and Black Rices

&lt;p&gt;The present study is focused on the variation in fatty acid (FA) composition of the different acyl lipids in red and black rices. Total lipids were fractionated by TLC into eight subfractions. Significant differences (&lt;em&gt;P&lt;/em&gt; &amp;lt; 0.05) in FA distribution were found among the different acyl lipids when the two cultivars were compared. There were no significant differences (&lt;em&gt;P&lt;/em&gt; &amp;gt; 0.05) in the positional distribution of FA in triacylglycerols; unsaturated FA was predominantly concentrated in the &lt;em&gt;sn&lt;/em&gt;-2 position while saturated FA primarily occupied the &lt;em&gt;sn&lt;/em&gt;-1 position or &lt;em&gt;sn&lt;/em&gt;-3 position in the oils. Significant differences (&lt;em&gt;P&lt;/em&gt; &amp;lt; 0.05) in FA distribution existed when the individual phospholipids were compared. Based on the FA composition of the different acyl lipids, it seems that red and black rices are very similar to each other with a few exceptions. The results suggest that these rice lipids may be well incorporated into our daily diet to improve value of the Japanese diet.&lt;/p&gt;

Composition and Regiodistribution of Fatty Acids in Triacylglycerols and Phospholipids from Red and Black Rices

ABSTRACTRegiospecific profiles of fatty acids (FA) of triacylglycerols (TAG) and phospholipids (PL) isolated from red and black rices were investigated. The lipids extracted from red and black rices were separated by thin‐layer chromatography (TLC) into eight subfractions, respectively. With a few exceptions, the major lipid components were TAG (76.4–80.5%), free FA (7.2–9.8%), and phospholipids (3.5–3.6%), while hydrocarbons, steryl esters, diacylglycerols (1,3‐DAG and 1,2‐DAG), and monoacylglycerols were present in minor proportions (0.1–4.1%). The PL components isolated from the two cultivars were phosphatidyl choline (52.3–53.7%), phosphatidyl ethanolamine (22.3–23.1%), phosphatidyl inositol (20.6–21.3%), and others (&lt;3.4%). No significant differences (P &lt; 0.05) in FA distribution were found when these cultivars were compared. The principal characteristics of the FA distribution in the TAG and PL were evident in the rices between the two cultivars: unsaturated FA were predominantly located at the sn‐2 position (77.3–96.8%), while saturated FA primary occupied the sn‐1 or the sn‐3 position (35.0–78.7%) in these lipids. The results of this study could provide useful information to both consumers and producers during manufacture of traditional rice foods in Japan.

여러 가지 특수미의 항산화 활성 및 항산화 성분

Dept. of Food Science and Technology, Chungbuk National University, Cheongju 361-763, KoreaAbstractThe objectives of this study were to determine antioxidant activity of the methanolic extracts from some specialty rices and to investigate relationships between antioxidant activities and antioxidant contents in the extracts. ABTS (2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)) radical cation scavenging activity, inhibitory effect on lipid peroxidation, chelating activity, reducing power and inhibitory effect on xanthine oxidase have been used to investigate the relative antioxidant activity of the extracts from specialty rices. The concentrations of total polyphenolics, phytic acid, and anthocyanin in the extracts were measured by spectrophotometric methods and vitamin E analysis was carried out by HPLC. The methanolic extracts prepared from black and red rices showed higher antioxidant activities and contained higher antioxidant compounds compared with other rices, apparently due to their intense red-purple color. The correlation coefficient between total polyphenolic content of methanolic extracts and ABTS radical cation scavenging activity, reducing power, and inhibitory effect of xanthine oxidase were 0.9921, 0.9856, and 0.8032, respectively.Key words: rice, antioxidant activity, antioxidant compound, correlation

여러 가지 특수미의 일부 항산화 성분 분석

The objective of this study was to determine antioxidant compounds in specialty rice including milled rice, brown rice, red rice, giant embryonic rice, black rice, green rice, and Goami consumed in Korea. The concentrations of total polyphenols (insoluble and soluble polyphenols), phytic acid, and anthocyanin in the samples were measured using spectrophotometric methods and vitamin E analysis was carried out by HPLC. The contents of the total polyphenolic compounds were 565 ㎎/100 g for black rice, 405 ㎎/100 g for red rice, 140 ㎎/100 g for giant embryo rice, 138 ㎎/100 g for Goami, 133 ㎎/100 g for brown rice, 127 ㎎/100 g for green rice, and 66 ㎎/100 g for white rice. The black and red rices were significantly high in polyphenolic contents compared with the other rices, apparently due to their intense red?purple color. Black rice, red rice, and Goami showed significantly higher vitamin E and phytic acid contents compared with other rices. Anthocyanins were determined in only black rice (302 ㎎/100 g) due to the detection limits of spectrophoto-metric assay. Although vitamin E and anthocyanin contents were relatively lower than polyphenolics among the samples, the specialty rice may contribute to the significant supply of antioxidant compounds to prevent oxidative stress due to the fact that rice is used as a staple food and consumed in large amounts in our diets. The results can be used to increase rice consumption by enhancing consumer awareness on health benefits of the rice.

Anthocyanin Composition in Black, Blue, Pink, Purple, and Red Cereal Grains

Anthocyanin pigments from a wide variety of edible and ornamental black, blue, pink, purple, red, and white wheat, barley, corn, rice, and wild rice were identified and quantified to evaluate their potential as natural colorants or functional food ingredients. The total anthocyanin contents varied significantly and exhibited a range of 7-3276 microg/g. Some grains, such as red rice and black rice, contained a limited number of pigments, whereas others, such as blue, pink, purple, and red corns, had complex anthocyanin profiles. Of the 42 anthocyanin compounds observed, 9 were characterized by comparison of the spectroscopic and chromatographic properties with those of authentic standards. The remaining compounds were tentatively identified on the basis of spectroscopic properties and electrospray ionization mass spectra. The most abundant anthocyanins were cyanidin 3-glucoside in black and red rices and in blue, purple, and red corns, pelargonidin 3-glucoside in pink corn, and delphinidin 3-glucoside in blue wheat.

Identification of phenolic compounds isolated from pigmented rices and their aldose reductase inhibitory activities

Two anthocyanins (cyanidin-3- O-β-glucoside and peonidin-3- O-β-glucoside) and other phenolic (ferulic acid) were, respectively isolated from black and pigmented brown rices ( Oryza sativa L. japonica) and their complete structures were determined by spectroscopic analyses (H NMR, C NMR and MALDI MASS). The HPLC profile of anthocyanins extracted from black rice showed cyanidin-3- O-β-glucoside as the first peak (85%) and peonidin 3- O-β- d-glucoside as the second (15%), while that of pigmented brown rice showed ferulic acid as the first peak (85.7%) and tocols as the second (14.3%). Several tocols were isolated and identified from the unsaponifiable fractions of both rices having some difference on their structures and amounts. The aldose reductase inhibitory activity of isolated compounds was in the following decreasing order: cyanidin-3-glucoside > quercetin > ferulic acid > peonidin-3-glucoside > tocopherol. All isolated compounds showed significant inhibitory activity against aldose reductase suggesting that both pigmented rices might contribute significantly in combating diabetic complications as health-promoting food ingredients in food processing.

Determination of trace element concentrations in ancient rices (red and black rices) and a present-day rice (Koshihikari) : Relationship among the trace element concentrations, species, harvest site and rice parts

Determination of trace element concentrations in ancient rices (red and black rices) and a present-day rice (Koshihikari) : Relationship among the trace element concentrations, species, harvest site and rice parts

Antioxidative Properties of Extracts from Ancient Rice Brans

In this study, the superoxide dismutase (SOD)-like activity and the ROS (superoxide anion, hydroxyl radical, singlet oxygen, t-butylperoxyl radical) scavenging activities were evaluated for the extracts from 2 varieties (black and red rices) of ancient rice brans (8 types) by the nitro-blue tetrazolium (NBT) and ESR-spin trapping methods. All the extracts from ancient rice brans (black and red rice) had SOD-like activity, which was stronger than those from present-day rice brans (Koshihikari, Akitakomachi, Haenuki). It was proven by NBT method that the activities of ancient rice brans were significantly stronger than those of L-ascorbic acid, however, L-ascorbic acid exhibited higher scavenging activity as evaluated by ESR spin-trap method. The ancient rice brans have remarkably strong ROS scavenging activities compared with those of the present-day rice brans (Koshihikari, etc.). The ROS scavenging activities and SOD-like activities of the extracts varied depending on the rice species and the planting region. In addition, the extracts from ancient rice brans inhibited the Maillard reaction, which is known to be involved in physiological aging processes. Thus, the present results suggest the utility of the extracts from ancient rice brans as antioxidative materials.