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Tadashi Yoshihashi - One of the best experts on this subject based on the ideXlab platform.
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Sensory test for aroma and quantitative analysis of 2-Acetyl-1-Pyrroline in Asian aromatic rice varieties.
Plant Production Science, 2006Co-Authors: Nguyen Loc Hien, Tadashi Yoshihashi, Wakil Ahmad Sarhadi, Yutaka HirataAbstract:(2006). Sensory Test for Aroma and Quantitative Analysis of 2-Acetyl-1-Pyrroline in Asian Aromatic Rice Varieties. Plant Production Science: Vol. 9, No. 3, pp. 294-297.
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Effect of Storage Conditions on 2–Acetyl-1–pyrroline Content in Aromatic Rice Variety, Khao Dawk Mali 105
Journal of Food Science, 2005Co-Authors: Tadashi Yoshihashi, Nguyen Thi Thu Huong, Vipa Surojanametakul, Patcharee Tungtrakul, Warunee VaranyanondAbstract:ABSTRACT: The effect of package and temperature on 2–acetyl-1–pyrroline content in milled aromatic rice during storage was investigated. 2 -Acetyl-1 -pyrroline content was decreased faster at higher storage temperature. However, fat acidity of rice was increased during storage and inversely correlated with 2–acetyl-1–pyrroline content at an early stage of storage. The difference in 2–acetyl-1 -pyrroline recovery from the samples, which were extracted with ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2–acetyl-1–pyrroline may occur in aromatic rice. These results suggested that the biosynthesis of 2–acetyl-1 -pyrroline before starch structure formation in rice kernel could play a key role in the aroma quality of aromatic rice.
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Area Dependency of 2-Acetyl-1-Pyrroline Content in an Aromatic Rice Variety, Khao Dawk Mali 105
Japan Agricultural Research Quarterly: JARQ, 2004Co-Authors: Tadashi Yoshihashi, Thi Thu Huong Nguyen, Nobuyuki KabakiAbstract:It has been stated that the quality of the aromatic rice variety, Khao Dawk Mali 105 is influenced by the environment of the production area or cultivation method. In this study, 2-Acetyl-1-Pyrroline content of various rice samples in Thailand was investigated. The results showed that the samples from the Northeastern region, where Khao Dawk Mali 105 was cropped in rain-fed paddy fields, were higher in 2-Acetyl-1-Pyrroline content. The "Tungkularonghai" area, stated as being the highest quality rice production area, had the highest content among the areas in Northeastern Thailand. Samples collected from non-drought condition areas showed lower content even in the Tungkularonghai area. However, differences in seeding method did not affect 2-Acetyl-1-Pyrroline content in the Tungkularonghai area. These results showed that dry climate might be a factor for 2-Acetyl-1-Pyrroline content in Khao Dawk Mali 105. Since Khao Dawk Mali 105 is a photosensitive variety, it was expected that the ripening stage becomes uniform at a certain period which should be suitable for 2-Acetyl-1-Pyrroline formation in paddy fields.
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quantitative analysis on 2 acetyl 1 pyrroline of an aromatic rice by stable isotope dilution method and model studies on its formation during cooking
Journal of Food Science, 2002Co-Authors: Tadashi YoshihashiAbstract:A quantitative analysis of 2-Acetyl-1-Pyrroline from aromatic rice samples using a stable isotope dilution method was developed. The compound was extracted from seedlings, roots, and husks at room temperature for 2 h, whereas milled or brown rice samples were extracted at 75 °C. The recovery of 2-acetyl- 1-pyrroline was linear from 5 to 5000 ng/g with sensitivity of less than 0.1 ng/g. 2-Acetyl-1-Pyrroline showed tautomerism with an imide form. The results revealed that 2-Acetyl-1-Pyrroline present in aromatic rice samples did not form during cooking or postharvest processes. Le 2-Acetyl-1-Pyrroline (AcPy), apportant un arome de pop corn, est un compose de flaveur important dans le riz aromatique. Cette etude decrit le developpement d'une methode de dosage par chromatographie gazeuse - spectrometrie de masse - controle d'ion selectionne pour l'analyse de AcPy dans du riz en utilisant une methode de dilution d'isotope stable. Elle evalue aussi les effets d'un traitement thermique en tant que modele de cuisson du riz sur la formation de AcPy.
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precursors of 2 acetyl 1 pyrroline a potent flavor compound of an aromatic rice variety
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Tadashi Yoshihashi, Nguyen Thi Thu Huong, Hideo InatomiAbstract:The biological formation of a potent flavor compound, 2-Acetyl-1-Pyrroline, in the aromatic rice variety (Khao Dawk Mali 105) was studied in seedlings and callus of the rice. Concentrations of 2-Acetyl-1-Pyrroline were determined by GC-MS-SIM using an isotope dilution method. Increases in concentration occurred when proline, ornithine, and glutamate were present in solution, with proline increasing the concentration by more than 3-fold compared to that of the control. Results of tracer experiments using (15)N-proline, (15)N-glycine, and proline-1-(13)C indicated that the nitrogen source of 2-Acetyl-1-Pyrroline was proline, whereas the carbon source of the acetyl group was not the carboxyl group of proline. 2-Acetyl-1-Pyrroline was formed in the aromatic rice at temperatures below that of thermal generation in bread baking, and formed in the aerial part of aromatic rice from proline as the nitrogen precursor.
Peter Schieberle - One of the best experts on this subject based on the ideXlab platform.
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Mechanistic Studies on the Formation of the Cracker-like Aroma Compounds 2-Acetyltetrahydropyridine and 2-Acetyl-1-Pyrroline by Maillard-type Reactions
The Maillard Reaction in Foods and Medicine, 2005Co-Authors: Peter Schieberle, Thomas HofmannAbstract:1-Pyrroline, the Strecker degradation product of the amino acids proline or ornithine, was identified as the key intermediate in the formation of the intense roast-smelling food odorants 2-acetyltetrahydropyridine (ATHP) and 2-Acetyl-1-Pyrroline (AP). Reacting 1-pyrroline with hydroxy-2-propanone yielded high amounts of only the ATHP, whereas the reaction with 2-oxopropanal gave only AP. Synthesized 2-(1-hydroxy-2-oxo-1-propyl)-pyrrolidine was shown to be the key precursor of ATHP. The last step in AP formation was shown to be simply an air oxidation of 2-acetylpyrrolidine, which is proposed to be formed from 1-pyrroline and 2-oxopropanal via the intermediate 2-(1,2-dioxo-1-propyl) pyrrolidine.
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studies on the key odorants formed by roasting of wild mango seeds irvingia gabonensis
Journal of Agricultural and Food Chemistry, 2000Co-Authors: A O Tairu, T. Hofmann, Peter SchieberleAbstract:Application of the aroma extract dilution analysis on a concentrate of volatiles obtained by solvent extraction and high vacuum distillation from roasted seeds (180 °C; 15 min) of wild mango (Irvingia gabonensis) revealed 32 odor-active compounds with flavor dilution (FD) factors ranging from 8 (low odor activity) to 2048 (high odor activity). The identification experiments based on the use of reference odorants revealed methional (cooked potato-like) followed by 2-Acetyl-1-Pyrroline (roasty, popcorn-like), butan-2,3-dione, pentan-2,3-dione, 2-ethyl-3,5-dimethylpyrazine, and 2,3-diethyl-5-methylpyrazine as the key aroma compounds among the 27 odorants identified. All odorants are reported for the first time as components of roasted wild mango seeds. Keywords: Wild mango; Irvingia gabonensis; aroma extract dilution analysis; methional; 2-Acetyl-1-Pyrroline
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New and Convenient Syntheses of the Important Roasty, Popcorn-like Smelling Food Aroma Compounds 2-Acetyl-1-Pyrroline and 2-Acetyltetrahydropyridine from Their Corresponding Cyclic α-Amino Acids
Journal of agricultural and food chemistry, 1998Co-Authors: Thomas Hofmann, Peter SchieberleAbstract:Novel straightforward syntheses have been developed supplying the important food odorants 2-Acetyl-1-Pyrroline (AP) and 2-acetyltetrahydropyridine (ATHP) in high yields. The four-step reaction sequence starts from the N-shielded cyclic alpha-amino acids L-proline and pipecolinic acid, respectively, which, in the first step, are converted into the N-shielded 2-acetyl derivatives. Removing the shielding group with trifluoroacetic acid afforded the 2-acetylpyrrolidine and 2-acetylpiperidine trifluoroacetate, respectively, which, upon increasing the pH of their aqueous solutions to 7.0, are spontaneously oxidized in high yields into AP (43% based on L-proline) or ATHP (35% based on pipecolinic acid), respectively, by air oxygen. The latter step is an important hint at the last step in the yet unclear formation pathways of both odorants in foodstuffs.
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2-Oxopropanal, Hydroxy-2-propanone, and 1-PyrrolineImportant Intermediates in the Generation of the Roast-Smelling Food Flavor Compounds 2-Acetyl-1-Pyrroline and 2-Acetyltetrahydropyridine
Journal of Agricultural and Food Chemistry, 1998Co-Authors: Thomas Hofmann, Peter SchieberleAbstract:On the basis of labeling experiments with [13C]6-glucose/unlabeled proline as well as quantitative data obtained in model studies using stable isotope dilution assays, 1-pyrroline and hydroxy-2-propanone were identified as effective intermediates in generating the roast-smelling food odorant 2-acetyltetrahydropyridine (ATHP; two tautomers). Synthesis of the key precursor compound, 2-(1-hydroxy-2-oxo-propyl)pyrrolidine, and studies on its degradation confirmed the important role of this intermediate in ATHP formation. Boiling of the intermediate for 30 min in aqueous solution generated >30% of ATHP on a molar basis. 1-Pyrroline and 2-oxopropanal were confirmed as important intermediates in the generation of the further roast food odorant, 2-Acetyl-1-Pyrroline (AP). On the basis of results of labeling experiments with [13C]6-glucose/unlabeled proline, two different mechanisms could be proposed. One leads to AP via 2-(1,2-dioxopropyl)pyrrolidine as the precursor with elimination of the aldehyde group in 2-ox...
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Potent odorants of rye bread crust-differences from the crumb and from wheat bread crust
Zeitschrift für Lebensmittel-Untersuchung und Forschung, 1994Co-Authors: Peter Schieberle, Werner GroschAbstract:Aroma extract dilution analyses revealed twenty-eight odorants in fresh rye bread crust and twenty in its crumb. On the basis of high flavour dilution factors, methional (boiled potato), 3-methylbutanal (malty), (E)-2-nonenal (green, tallowy), (E,E)-2,4-decadienal (fatty) and acetic acid (sour, pungent) belonged to the potent odorants of the crust, and phenylacetaldehyde, (E)-2-nonenal and (E,E)-2,4-decadienal to those of the crumb. Compared with the crust, especially the odour activities of methional, 3-methylbutanal, 2-ethyl-3,5-dimethyl-pyrazine and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were significantly lower in the crumb. Calculation of the odour activity values (OAV; ratio of concentration to odour threshold) indicated that the higher OAV of methional in the rye crust and the higher OAV of 2-Acetyl-1-Pyrroline in the wheat bread crust mainly contributed to the flavour difference of the two kinds of bread. Aromaextraktverdünnungsanalysen ergaben 28 Geruchsstoffe in frischer Roggenbrotkruste und 20 in der Krume. Aufgrund hoher FD-Faktoren gehörten Methional (gekochte Kartoffel), 3-Methylbutanal (malzartig), (E)-2-Nonenal (grün, talgig), (E,E)-2,4-De-cadienal (fettig) und Essigsäure (sauer, stechend) zu den potenten Geruchsstoffen der Kruste sowie Phenylacetal-dehyd, (E)-2-Nonenal und (E,E)-2,4-Decadienal zu denen der Krume. Im Vergleich zur Kruste waren insbesondere die Geruchsaktivitäten von Methional, 3-Methylbutanal, 2-Ethyl-3,5-dimethylpyrazin und 4-Hydroxy-2,5-dimethyl-3 (2H)-furanon in der Krume deutlich erniedrigt.-Die Berechnung von Aromawerten (Quotient aus Konzentration und Geruchsschwelle) zeigte, daß insbesondere der erheblich höhere Aromawert des Methionals in der Roggenbrotkruste und der des röstig, süß riechenden 2-Acetyl-1-pyrrolins in der Weißbrotkruste wesentlich zum Aromaunterschied beider Brotarten beiträgt.
Keith R. Cadwallader - One of the best experts on this subject based on the ideXlab platform.
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Spray-chilling encapsulation of 2-Acetyl-1-Pyrroline zinc chloride using hydrophobic materials: Storage stability and flavor application in food.
Food chemistry, 2018Co-Authors: Yun Yin, Keith R. CadwalladerAbstract:Abstract 2-Acetyl-1-Pyrroline (2AP) is a popular yet highly unstable aroma compound, which limits its commercial use as a flavoring ingredient. The stability and application of spray-chilled paraffin-coated microcapsules of 2AP zinc chloride complex (2AP–ZnCl2) were investigated in this study. 2AP–ZnCl2 microcapsules (0.081% (w/w) 2AP loading) and unprotected 2AP–ZnCl2 complex were subjected to ambient storage at four different relative humidities (RH; ∼0%, ∼22.5%, ∼43.2% and ∼100%). The results showed that the microcapsules had significantly greater 2AP stability compared with the unprotected complex under all storage conditions studied. A flavor application study using instant rice was also performed to validate the potential effectiveness of using 2AP–ZnCl2 microcapsules as a flavoring agent. Full 2AP recovery was achieved after the cooking process, where the controlled release function of the microcapsules was clearly exhibited. The results demonstrated that microencapsulation of 2AP–ZnCl2 allows for more flexible handling/storage practices and has potential for application by the flavor industry.
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Starch-Flavor Complexation Applied to 2-Acetyl-1-Pyrroline.
Journal of agricultural and food chemistry, 2018Co-Authors: Bethany J. Hausch, Jeanette A. Little, James A. Kenar, Keith R. CadwalladerAbstract:The pleasant popcorn-like smelling compound 2-Acetyl-1-Pyrroline (2AP) occurs naturally in many foods but is scarcely used as a flavoring agent due to its great instability. In this work, we evaluate the potential of high amylose corn starch to complex and stabilize 2AP. The methodology was first optimized using model compounds, 2-acetylpyridine and 2-acetyl-2-thiazoline, and then applied to 2AP. Complexes were successfully prepared and characterized using X-ray diffraction, gas chromatography, and differential scanning calorimetry. Loadings of up to 0.504 (±0.071)% 2AP were achieved, and storage studies showed that over half of the flavor was retained after 2 weeks at 0% relative humidity. To our knowledge, this is the first demonstration that 2AP can form amylose inclusion complexes and may lead to a method to effectively stabilize this labile aroma compound.
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Spray-chilling encapsulation of 2-Acetyl-1-Pyrroline zinc chloride complex using hydrophobic materials: Feasibility and characterization of microcapsules
Food chemistry, 2018Co-Authors: Yun Yin, Keith R. CadwalladerAbstract:A moisture-sensitive 2-Acetyl-1-Pyrroline zinc chloride complex (2AP-ZnCl2) was successfully encapsulated by spray-chilling, using a hydrophobic moisture barrier as a practical way to protect the complex and to help facilitate its general use in food applications. Use of octacosane as wall material provided a flavor retention of 65.3%. The results from scanning electron microscopy (SEM) and X-ray micro-computed tomography (X-ray micro-CT) indicated desirable morphological characteristics of the matrix type microcapsules. Gas chromatography (GC) and absorbance spectroscopy were used for chemical quantitation of 2AP and ZnCl2, respectively, in the microcapsules. Results revealed no degradation of 2AP occurred as a result of the encapsulation process. This study is the first to demonstrate the feasibility of producing high quality microcapsules from labile flavor complexes by spray-chilling. The use of generally recognized as safe (GRAS) substances, including 2AP and ZnCl2, may allow for widespread commercial use of 2AP as a flavor ingredient.
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Stabilization of the potent odorant 2-Acetyl-1-Pyrroline and structural analogues by complexation with zinc halides.
Journal of agricultural and food chemistry, 2014Co-Authors: Ming Chih Fang, Keith R. CadwalladerAbstract:2-Acetyl-1-Pyrroline (2AP) and the structurally similar compounds 6-acetyl-2,3,4,5-tetrahydropyridine (ATHP, along with its tautomer 6-acetyl-1,2,3,4-tetrahydropyridine), 2-propionyl-1-pyrroline (2PP), and 2-acetyl-2-thiazoline (2A2T) are well-known potent odorants in various food products. However, due to the highly unstable nature of these compounds, especially 2AP and ATHP, they are scarcely used commercially in flavor formulations. A novel and attractive method for the stabilization of these potent odorants in dry powder form is presented. Coordination of 2AP, ATHP, 2PP, and 2A2T to zinc ions (ZnI2, ZnBr2, or ZnCl2) resulted in the formation in high yields of stable crystalline complexes, which upon hydration release the free odorant. Infrared spectroscopy was used to study the coordination complexes. 2AP contains donor atoms, which coordinate (with covalent character) through both the heterocyclic nitrogen and carbonyl oxygen atoms to the zinc ion. This is also the case for ATHP and 2PP, but not for 2A2T, because the sulfur group in 2A2T provides a third possible donor site. Stability studies showed that the 2AP-ZnI2 complex (with 14% loading) maintained >94% retention of 2AP after 3 months of storage at ambient temperature in a dry environment. Meanwhile, the ATHP-ZnI2 complex was similarly stable and retained 89% of the ATHP after 3 months of storage. This stabilization technology may enable the commercial use of this powerful aroma compound as a flavoring agent.
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Aroma components of American country ham.
Journal of food science, 2007Co-Authors: H. Song, Keith R. CadwalladerAbstract:The aroma-active compounds of American country ham were investigated by using direct solvent extraction-solvent assisted flavor evaporation (DSE-SAFE), dynamic headspace dilution analysis (DHDA), gas chromatography-olfactometry (GCO), aroma extract dilution analysis (AEDA), and gas chromatography-mass spectrometry (GC-MS). The results indicated the involvement of numerous volatile constituents in the aroma of country ham. For DHDA, 38 compounds were identified as major odorants, among them, 1-octen-3-one, 2-Acetyl-1-Pyrroline, 1-nonen-3-one, decanal, and (E)-2-nonenal were the most predominant, having FD-factors >or= 125 in all 3 hams examined, followed by 3-methylbutanal, 1-hexen-3-one, octanal, acetic acid, phenylacetaldehyde, and Furaneol. For the DSE-SAFE method, the neutral/basic fraction was dominated by 1-octen-3-one, methional, guaiacol, (E)-4,5-epoxy-(E)-decenal, p-cresol as well as 3-methylbutanal, hexanal, 2-Acetyl-1-Pyrroline, phenylacetaldehyde, and gamma-nonalactone. The acidic fraction contained mainly short-chain volatile acids (3-methylbutanoic acid, butanoic acid, hexanoic acid, and acetic acid) and Maillard reaction products (for example, 4-hydroxy-2,5-dimethyl-3(2H)-furanone). The above compounds identified were derived from lipid oxidation, amino acid degradation, and Maillard/Strecker and associated reactions. Both methods revealed the same nature of the aroma components of American country ham.
Xiangru Tang - One of the best experts on this subject based on the ideXlab platform.
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Exogenous proline induces regulation in 2-Acetyl-1-Pyrroline (2-AP) biosynthesis and quality characters in fragrant rice (Oryza sativa L.).
Scientific reports, 2020Co-Authors: Haowen Luo, Axiang Zheng, Jinhai Liu, Pipeng Xing, Rifang Lai, Tantan Zhang, Xiangru TangAbstract:Proline is one of the precursors of the biosynthesis of 2-Acetyl-1-Pyrroline (2-AP) which is the key and characteristic volatile component of fragrant rice aroma. In order to study the effects of exogenous proline on 2-AP biosynthesis and other grain quality attributes in fragrant rice, two indica fragrant rice cultivars, "Meixiangzhan-2" and "Xiangyaxiangzhan", and one japonica fragrant rice, "Yunjingyou", were used in present study. At initial heading stage, proline solutions at 0 (CK), 0.10 (Pro1), 0.20 (Pro2) and 0.50 (Pro3) g L-1 were applied as foliar spray solution to fragrant rice plants. Compared with CK, Pro1, Pro2 and Pro3 treatments significantly increased the grain 2-AP content. The significant up-regulation effects due to proline treatments were observed in the contents of proline, △1-pyrrolidine-5-carboxylic acid (P5C) and △1-pyrroline which involved in 2-AP formation. Exogenous proline application also significantly decreased the grain γ-aminobutyric acid (GABA) content. Furthermore, proline treatments enhanced the activity of proline dehydrogenase (ProDH) as well as transcript level of gene PRODH. On the other hand, the transcript level of gene BADH2 and activity of betaine aldehyde dehydrogenase (BADH) decreased under proline treatments. Proline treatments (Pro2 and Pro3) also increased the grain protein content by 3.57-6.51%. Moreover, 32.03-34.25% lower chalky rice rate and 30.80-48.88% lower chalkiness were recorded in proline treatments (Pro2 and Pro3) for both Meixiangzhan and Xiangyaxiangzhan whilst for Yunjingyou, foliar application of proline had no significant effect on chalky rice rate and chalkiness. There was no remarkable difference observed in grain milled quality (brown rice rate, milled rice rate and head rice rate) and amylose content between CK and proline treatments. In conclusion, exogenous proline enhanced the 2-AP biosynthesis and promoted some grain quality characters of fragrant rice.
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Application of saline to seeds enhances the biosynthesis of 2-Acetyl-1-Pyrroline in aromatic rice seedlings (Oryza sativa L.)
Acta Physiologiae Plantarum, 2020Co-Authors: Haowen Luo, Jinhai Liu, Pipeng Xing, Rifang Lai, Tantan Zhang, Zhimin Wang, Xiangru TangAbstract:Salinity was shown to impact the formation of 2-Acetyl-1-Pyrroline (2-AP), the key flavour compound in aromatic rice cultivars. To study the effects of saline application to seeds on 2-AP biosynthesis in aromatic rice and to further investigate the enzymatic and molecular mechanisms involved, the present study was conducted with nine treatments. The seeds of three aromatic rice cultivars were primed or soaked in 0.01, 0.02, 0.05 and 0.10 mM sodium chloride solutions, and the seeds that were both primed and soaked in distilled water were considered the control group. Then, the seedlings were allowed to grow in an artificial climate box. The results showed that both priming and soaking seeds with saline significantly increased the 2-AP content in aromatic rice seedlings. The highest 2-AP content was recorded in the seeds primed with 0.10 mM sodium chloride. In the seeds treated with saline, increased amounts of proline, P5C and Δ1-pyrroline were observed and resulted in enhanced 2-AP biosynthesis through induced gene expression (P5CS1, P5CS2 and PRODH) and activities of enzymes including PDH and P5CS. In summary, application of saline to seeds increased 2-AP content in aromatic rice seedlings by up-regulating the related precursors contents, enzymes activities and genes expression.
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Foliar application of sodium selenate induces regulation in yield formation, grain quality characters and 2-Acetyl-1-Pyrroline biosynthesis in fragrant rice
BMC plant biology, 2019Co-Authors: Haowen Luo, Axiang Zheng, Shenggang Pan, Xiangru TangAbstract:Selenium (Se) is a beneficial element for higher plants and essential for mammals. To study the effect of the foliar application of sodium selenate on fragrant rice performance, a pot experiment was conducted in Guangdong, China. At the initial heading stage, one-time foliar application of sodium selenate with concentrations of 0, 10, 20, 30, 40 and 50 μmol·L− 1 (named CK, Se1, Se2, Se3, Se4 and Se5, respectively) were foliar applied on two fragrant rice varieties, ‘Meixiangzhan-2’ and ‘Xiangyaxiangzhan’. Selenate application at the initial heading stage not only improved the grain yield of fragrant rice by increasing the seed-setting rate and grain weight, but also promoted the grain quality by increasing crude protein contents and lowering the chalky rice rate. Furthermore, Se applications enhanced the biosynthesis of 2-acetyl-1- pyrroline (2-AP), the main aromatic compound, by increasing the contents of precursors (△1- pyrroline, proline and pyrroline-5-carboxylic acid (P5C)) and the activities of enzymes (proline dehydrogenase (PRODH), △1-pyrroline-5-carboxylic acid synthetase (P5CS), and ornithine aminotransferase (OAT)) in fragrant rice. The results also showed that foliar application of sodium selenate enhanced the antioxidant system of both varieties by promoting the activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and reducing the contents of malondialdehyde (MDA). Furthermore, the real-time PCR analyses depicted that foliar application of selenate up-regulated the GPX1, GPX4 and CATC transcripts. The higher antioxidative enzymatic activities might strength the stress resistant to ensure the stability of yield in fragrant rice form abiotic stress. Foliar applications of sodium selenate at the initial heading stage increased the grain 2-AP content by enhancing the biosynthesis-related enzymes and precursors. The grain yield and quality of fragrant rice also increased due to selenate application. Furthermore, foliar application of selenate promoted the activities of enzymes such as POD, SOD and CAT and up-regulated the expression of gene GPX4, GPX1 and CATC.
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Regulations in 2-Acetyl-1-Pyrroline contents in fragrant rice are associated with water-nitrogen dynamics and plant nutrient contents
Journal of Cereal Science, 2019Co-Authors: Yongjian Tang, Umair Ashraf, Hua Tian, Shenggang Pan, Meiyang Duan, Shuli Wang, Xiangru TangAbstract:Abstract Water (W) and nitrogen (N) have pronounced effects on 2-Acetyl-1-Pyrroline (2AP) contents and nutrient acquisition in fragrant rice. Field experiments were conducted during the early (March–July) and the late (July–November) seasons of 2013. Two water regimes i.e., W0 (well-watered, soil water potential was 0 kPa) and W1 (soil water potential was −25± 5 kPa) and two nitrogen levels i.e., N0 (0 kg N/ha) and N1 (60 kg N/ha (applied in addition to basal dose) were applied to two fragrant rice cultivars i.e., ‘Nongxiang 18’ and ‘Basmati 385’ at booting stage. All treatments were applied with 90–90-195 kg N–P–K ha−1 as basal fertilizer and at five days after transplanting, more N was added at 30 kg/ha. Results showed that the interactive effects of W and N influenced 2AP content in grains of both aromatic rice cultivars in both seasons. Compared to W1N0, the 2AP contents of ‘Nongxiang 18’ and ‘Basmati 385'were increased by 37.74% and 55.78% as well as 68.35% and 47.10% at W1N1 for early and late season, respectively. Moreover, W1N1 increased total nitrogen contents in leaves and total potassium contents in leaves and stem sheath of both rice cultivars, whereas, grain 2AP contents were significantly related to the total N and N/P ratio in leaves.
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The genetics and biosynthesis of 2-Acetyl-1-Pyrroline in fragrant rice.
Plant physiology and biochemistry : PPB, 2018Co-Authors: Nnaemeka Emmanuel Okpala, Meiyang Duan, Xiangru TangAbstract:Rice (Oryza sativa L.) is a staple food for the majority of the world's population. Rice fragrance, aroma, or scent is not just a cooking quality, but also an eating quality of rice. Rice fragrance is a trait that is widely desired among rice consumers. Consequently, rice producers are sorting for rice cultivars with strong fragrance. High demand for fragrant rice cultivars has prompted rice breeders and researchers to investigate the genetics and the ways to improve fragrance in rice. It has been established by many researches that fgr gene on the chromosome 8 of rice controls its fragrance. As with other plants, rice contains BADH but because rice does not accumulate GB, a catalyst for BADH coding, BADH1 on chromosome 4 of rice and BADH2 on chromosome 8 of rice have been widely reported to be responsible for encoding BADH. badh2, a recessive allele of BADH2 has been confirmed to be responsible for fragrance in rice. badh2 and its alleles have been associated with the accumulation and synthesis of 2AP. Proline, ornithine, glutamate, methylglyoxal, Δ1-pyrroline-5-carboxylate synthetase and glyceraldehyde-3-phosphate dehydrogenase have all been identified as the precursors for the synthesis and accumulation of 2AP. By reviewing and summarising the main results of various researchers, we have been able to elucidate how various genes and metabolites influence 2AP accumulation in fragrant rice. It is our hope that this paper will be beneficial to researchers, who are working on the improvement of rice fragrance.
Norbert De Kimpe - One of the best experts on this subject based on the ideXlab platform.
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New short and general synthesis of three key Maillard flavour compounds: 2-Acetyl-1-Pyrroline, 6-acetyl-1,2,3,4-tetrahydropyridine and 5-acetyl-2,3-dihydro-4H-1,4-thiazine.
Food chemistry, 2014Co-Authors: Jurgen Deblander, Norbert De Kimpe, An Adams, Sam Van Aeken, Kourosch Abbaspour TehraniAbstract:A new general synthetic route towards three key Maillard flavour compounds, namely 2-Acetyl-1-Pyrroline, 6-acetyl-1,2,3,4-tetrahydropyridine and 5-acetyl-2,3-dihydro-4H-1,4-thiazine, was developed. The key step in the process is the methylenation reaction of azaheterocyclic carboxylic esters by means of dimethyltitanocene, giving rise to intermediate vinyl ethers which can be considered as excellent and stable precursors for the title compounds, as a simple acidic treatment of these precursors suffices to release the characteristic Maillard flavours.
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Formation of pyrazines and 2-Acetyl-1-Pyrroline by Bacillus cereus
Food Chemistry, 2007Co-Authors: An Adams, Norbert De KimpeAbstract:Abstract The production of alkylpyrazines and 2-Acetyl-1-Pyrroline by different Bacillus cereus strains, which has been previously reported, was studied in detail. B. cereus ATCC 27522 produced the highest amounts of flavour compounds when grown as surface cultures on plate count agar. Pyrazine, methylpyrazine, 2,5-dimethylpyrazine, trimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine were produced in low amounts. Since they were also detected in control flasks, an enzymatic formation was concluded to be unlikely. Only the production of 3-ethyl-2,5-dimethylpyrazine was in all cases significantly different from the control. Detailed precursor studies revealed that the production of 2-Acetyl-1-Pyrroline by B. cereus ATCC 27522 proceeds via acetylation of 1-pyrroline, a metabolic degradation product of proline and ornithine. Comparison of results obtained from dynamic headspace and simultaneous steam distillation – solvent extraction showed that the use of a non-thermal extraction method is essential to obtain reliable results on the biological formation of these Maillard flavour compounds.
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Novel syntheses of the major flavor components of bread and cooked rice.
Journal of Agricultural and Food Chemistry, 1996Co-Authors: Norbert De Kimpe, M. KeppensAbstract:A new synthetic pathway toward the Maillard flavor compounds 6-acyl-1,2,3,4-tetrahydropyridines and 2-Acetyl-1-Pyrroline is presented. The reaction sequence involves deprotonation of a vicinal diimine and subsequent alkylation with an N,N-diprotected ω-bromoalkylamine, followed by deprotection and intramolecular transimination of the functionalized intermediate. Acidic workup affords the above-mentioned heterocycles, which are principal flavor constituents of bread and cooked rice, respectively. In addition, the synthesis of the more stable diethyl acetal of 2-Acetyl-1-Pyrroline is described. Keywords: Rice flavor; bread flavor; 2-Acetyl-1-Pyrroline; 6-acetyl-1,2,3,4-tetrahydropyridine; Maillard
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Synthesis of 2-Acetyl-1-Pyrroline, the principal rice flavor component
Journal of Agricultural and Food Chemistry, 1993Co-Authors: Norbert De Kimpe, Christian V. Stevens, M. KeppensAbstract:A new straightforward synthesis of 2-Acetyl-1-Pyrroline, the principal rice flavor component with a cracker-like flavor, is reported. The reaction sequence involves the conversion of pyrrolidine into tripyrroline, subsequent hydrocyanation of the latter into 2-cyanopyrrolidine, oxidation into 2-cyano-1-pyrroline, and Grignard addition of methylmagnesium iodide, affording an overall yield of 16-19% from pyrrolidine. In similar way, 2-propionyl-1-pyrroline, a recently discovered flavor component of popcorn, was prepared in addition to several higher analogues, i.e., 2-acyl-1-pyrrolines. Also, the synthesis of 2-(acetyl-d 3 )-1-pyrroline, a deuterated derivative of the rice flavor compound which is useful for the stable isotope dilution assay, is described
