A correlation between tocopherol content and antioxidant activity in seeds and germinating seeds of soybean cultivars.

BACKGROUND: Tocopherols are crucial lipid-soluble antioxidants and essential nutrients. There is increasing interest in the biofortification of crops with vitamin E for reducing micronutrient malnutrition. However, relatively little is known about the development of soybean cultivars with high levels of tocopherol through combined breeding. RESULT: Tocopherol contents of seeds and germinating seeds of 28 Korean soybean cultivars were analyzed and evaluated for health-promoting activities. Total tocopherol concentrations ranged from 203.9 to 503.1 µg g⁻¹ in seeds and from 20.1 to 230.1 µg g⁻¹ in germinating seeds. The traditional landraces of HaNagari (HN, 503.1 µg g⁻¹), Orialtae (OL, 486.6 µg g⁻¹), SuMoktae (SM, 476.5 µg g⁻¹) and SoRitae (SR, 475.5 µg g⁻¹) showed high levels of tocopherol content. The contents of the four isomers of tocopherol in seeds and germinating seeds were correlated with lipid peroxidation. The γ- and δ-tocopherol contents in seeds were related to 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity (0.434; P < 0.01 and 0.373; P < 0.05). CONCLUSION: Total tocopherol content was higher in soybean landraces as compared with modern cultivars developed by cross-breeding. These results suggest that soybean breeding is necessary to increase tocopherol levels.

Characterization of volatile aroma compounds in cooked black rice.

Black rice ( Oryza sativa L.), an aromatic specialty rice popular in Asia, has a unique flavor, the volatile chemistry of which has not been reported. The objectives of this research were to study volatile profiles of cooked black rice and to characterize the odor-active compounds. Thirty-five volatile compounds were identified by gas chromatography-mass spectrometry using a dynamic headspace system with Tenax trapping. Aldehydes and aromatics were quantitatively in the greatest abundance, accounting for 80.1% of total relative concentration of volatiles. The concentration of 2-acetyl-1-pyrroline (2-AP) was high, exceeded only by hexanal, nonanal, and 2-pentylfuran. A total of 25 odor-active compounds, determined by gas chromatography-olfactometry, were applied to principal component analysis, demonstrating significant differences between a black and a traditional white rice cultivar in terms of aroma and explaining 93.0% of the total variation. 2-AP, guaiacol, indole, and p-xylene largely influenced the difference between the aroma in cooked black and white rice. 2-AP and guaiacol were major contributors to the unique character of black rice based on odor thresholds, relative concentrations, and olfactometry.

Physicochemical Properties of ß-Glucan from Acid Hydrolyzed Barley.

This study was performed to investigate changes in the content and purity, as well as physical characteristics of ß-glucan extracted from acid hydrolyzed whole grain barleys. Waxy and non-waxy barleys (Hordeum vulgare) were hydrolyzed with different concentrations of HCl (0.1~0.5 N) for 1 h. As the HCl concentration increased, the contents of total and soluble ß-glucan from acid hydrolyzed barley decreased. However the ratio of soluble/total ß-glucan content and purities of ß-glucan significantly increased. The ratio of ß-(1→4)/ß-(1→3) linkages, molecular weight, and viscosity of soluble ß-glucan of raw barleys were 2.28~2.52, 6.0~7.0×10(5) g/mol, and 12.8~32.8 centipoise (cP). Those of isolated soluble ß-glucan were significantly decreased to 2.05~2.15, 6.6~7.8×10(3) g/mol, and 3.6~4.2 cP, respectively, with increasing acid concentration. The re-solubility of raw barley ß-glucan was about 50%, but increased to 97% with increasing acid concentration. Acid hydrolysis was shown to be an effective method to produce ß-glucan with high ratio of soluble ß-glucan content, purity, water solubility, and low viscosity.

Substituting normal and waxy-type whole wheat flour on dough and baking properties.

Normal (cv. Keumkang, KK) and waxy-type (cv. Shinmichal, SMC) whole wheat flour was substituted at 20 and 40% for white wheat flour (WF) during bread dough formulation. The flour blends were subjected to dough and baking property measurement in terms of particle size distribution, dough mixing, bread loaf volume and crumb firmness. The particle size of white wheat flour was the finest, with increasing coarseness as the level of whole wheat flour increased. Substitution of whole wheat flour decreased pasting viscosity, showing all RVA parameters were the lowest in SMC40 composite flour. Water absorption was slightly higher with 40% whole wheat flour regardless of whether the wheat was normal or waxy. An increased mixing time was observed when higher levels of KK flour were substituted, but the opposite reaction occurred when SMC flour was substituted at the same levels. Bread loaf volume was lower in breads containing a whole wheat flour substitution compared to bread containing only white wheat flour. No significant difference in bread loaf volume was observed between normal and waxy whole flour, but the bread crumb firmness was significantly lower in breads containing waxy flour. The results of these studies indicate that up to 40% whole wheat flour substitution could be considered a practical option with respect to functional qualities. Also, replacing waxy whole flour has a positive effect on bread formulation over normal whole wheat flour in terms of improving softness and glutinous texture.

Hydration and Pasting Properties of Oat (Avena sativa) Flour.

Three oat cultivars and one oat breeding line were evaluated for chemical, hydration and pasting properties. Protein, starch and ß-glucan levels ranged 11.13∼14.37, 56.37∼64.86 and 3.44∼4.76%, respectively. The oat cultivars Daeyang and Seonyang contained higher ß-glucan levels of 4.76 and 4.35%. The Daeyang variety had a higher water absorption index (WAI) of 2.83∼3.35 (g/g), but a lower water solubility index (WSI) of 8.67 ∼11.08%. Daeyang and Seonyang cultivars showed higher peak and trough viscosity, but lower breakdown and setback, indicating that they easily swell, and thus could possibly provide the desirable viscosity of an oat product. The ß-glucan levels were correlated positively with WAI, peak and trough viscosity, and negatively to WSI, breakdown and setback viscosity.