Using a dynamic headspace system with Tenax trap, GC-MS, GC-olfactometry (GC-O), and multivariate analysis, the aroma chemistry of six distinctly different rice flavor types (basmati, jasmine, two Korean japonica cultivars, black rice, and a nonaromatic rice) was analyzed. A total of 36 odorants from cooked samples were characterized by trained assessors. Twenty-five odorants had an intermediate or greater intensity (odor intensity >or= 3) and were considered to be major odor-active compounds. Their odor thresholds in air were determined using GC-O. 2-Acetyl-1-pyrroline (2-AP) had the lowest odor threshold (0.02 ng/L) followed by 11 aldehydes (ranging from 0.09 to 3.1 ng/L), guaiacol (1.5 ng/L), and 1-octen-3-ol (2.7 ng/L). On the basis of odor thresholds and odor activity values (OAVs), the importance of each major odor-active compound was assessed. OAVs for 2-AP, hexanal, ( E)-2-nonenal, octanal, heptanal, and nonanal comprised >97% of the relative proportion of OAVs from each rice flavor type, even though the relative proportion varied among samples. Thirteen odor-active compounds [2-AP, hexanal, ( E)-2-nonenal, octanal, heptanal, nonanal, 1-octen-3-ol, ( E)-2-octenal, ( E, E)-2,4-nonadienal, 2-heptanone, ( E, E)-2,4-decadienal, decanal, and guaiacol] among the six flavor types were the primary compounds explaining the differences in aroma. Multivariate analysis demonstrated that the individual rice flavor types could be separated and characterized using these compounds, which may be of potential use in rice-breeding programs focusing on flavor.

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.

In order to identify the degree of salinity tolerance of the indica and japonica rice groups, 10 varieties were tested under saline and non-saline conditions. Twelve-day-old seedlings were grown in normal culture solution, then initially salinized at an electrical conductivity (EC) of 6 dS/m for 4 days, and finally salinized at an EC of 12 dS/m for the next 14 days. The growth parameters, and Na and K absorption in the shoot were measured to characterize the tolerance level of the two rice groups. Reduction in all growth parameters of tolerant varieties was significantly lower in indica varieties than in japonica varieties. Tolerant indica varieties were good Na excluders, absorbed high amounts of K, and maintained a low Na/K ratio in the shoot. Tolerant japonica varieties also absorbed less Na but were not as good excluders as indica varieties. Shoot K concentration alone did not show any relationship to salinity tolerance. These results indicate that, for all parameters measured, the tolerance level of indica was higher than that of japonica.

wileyonlinelibrary.comspeed, and simplicity of the process. [1][2][3][4][5] Although vertical orientation of lamellar and cylindrical nanodomains of block copolymers on a substrate is desirable, parallel orientation is usually obtained in a thin fi lm because of different affi nity between two block segments in a block copolymer toward the substrate and/or air. To induce vertical orientation, diverse preor post-treatments to neutralize the preferential affi nity have been introduced in the literature, for instance, solvent vapor annealing, [6][7][8][9] surface neutralization by random copolymer brush treatment, [10][11][12] blend system, [ 13 ] graphoepitaxy, [ 14,15 ] temperature gradient, [ 16,17 ] electric fi eld [ 18,19 ] or top coating. [20][21][22] Among them, solvent vapor annealing is one of the most powerful post-treatment methods for developing vertical orientation of block copolymer nanodomains. However, this method is diffi cult to apply for industrial applications owing to the use of solvents and the dewetting problem. To avoid using solvent, thermal annealing of block copolymer thin fi lms would be the most promising platform for commercialization of DSA due to easy and large scale process. However, to induce vertically oriented nanodomains, neutralization of a substrate by various surface modifi cations, for instance, functionalization with random copolymers, introducing rough substrates, employing graphene fi lms or nanoparticle monolayers, [ 11,13,[23][24][25] is still needed to tune interfacial interactions between a substrate and each block of the block copolymer. Therefore, a simple and cost-effective DSA process that does not require above-mentioned neutralization methods and solvent vapor annealing is demanded for the fabrication of vertically oriented nanodomains to compete with conventional top-down lithography.Kramer and co-workers [ 26 ] investigated the effect of block copolymer chain architecture on the orientation of nanodomains in relatively thick fi lms (600-800 nm) using poly(cyclohexylethylene)-block -poly(ethylene) (PCHE-b -PE) block copolymers. They found that PCHE-b -PE-b -PCHE triblock copolymer showed perpendicularly oriented nanodomains by introducing lower surface energy block as the midblock, whereas PCHE-b -PE diblock copolymer exhibited parallel Vertical Orientation of Nanodomains on Versatile Substrates through Self-Neutralization Induced by Star-Shaped Block CopolymersSangshin Jang , Kyuseong Lee , Hong Chul Moon , Jongheon Kwak , Jicheol Park , Gumhye Jeon , Won Bo Lee , and