Heptyl acetate

Binding of aromatic compounds with soy protein isolate in an aqueous model: Effect of pH.[Pubmed:31608468]

J Food Biochem. 2019 Oct;43(10):e12817.

Interactions of the flavoring compounds hexyl acetate (HxAc), Heptyl acetate (HpAc), linalyl formate (LiFo), linalyl acetate (LiAc), geraniol, linalool, limonene, and myrcene with soy protein isolate (SPI) were estimated in pH 3.0, 6.0, and 9.0 aqueous solutions using headspace solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). The binding capacity of HxAc, HpAc, LiFo, LiAc, geraniol, and linalool increased in the pH of the medium from 3 to 9. For limonene and myrcene, an unexpected increase in headspace concentration or a "salting-out" effect was observed. Between pH 3 and 9, better accessibility to the primary hydrophobic sites as a result of a modification to the protein's flexibility was observed. PRACTICAL APPLICATIONS: SPME method is a technology of dynamic adsorption for flavors. The lowest level of lead be practicably detected in food as low as the practiced concentration of flavors (0.01-0.1 mM) in our study. At low concentrations of flavors, it is close to the actual flavor's concentration of food. In the previous studies, the technology, such as equilibrium dialysis, headspace-gas phase which need higher concentration of flavors (>0.2 mM). The interaction between flavors and protein has a different binding law at high and low concentrations. As we produced the acid fruit soy protein milk beverage, the off-flavors present in the beverage were due to the change in the interaction between denature SPI and flavors. The present work is aimed at paving the way for further research to elucidate flavor imbalances in acid fruit soy protein milk beverage.

Molecular and functional characterization of three odorant-binding proteins from the wheat blossom midge, Sitodiplosis mosellana.[Pubmed:31017726]

Insect Sci. 2020 Aug;27(4):721-734.

Sitodiplosis mosellana, a periodic but devastating wheat pest, relies on wheat spike volatiles as a cue in selecting hosts for oviposition. Insect odorant-binding proteins (OBPs) are thought to play essential roles in filtering, binding and transporting hydrophobic odorant molecules to specific receptors. To date, the molecular mechanisms underlying S. mosellana olfaction are poorly understood. Here, three S. mosellana antenna-specific OBP genes, SmosOBP11, 16 and 21, were cloned and bacterially expressed. Binding properties of the recombinant proteins to 28 volatiles emitted from wheat spikes were investigated using fluorescence competitive binding assays. Sequence analysis suggested that these SmosOBPs belong to the Classic OBP subfamily. Ligand-binding analysis showed that all three SmosOBPs preferentially bound alcohol, ester and ketone compounds, and SmosOBP11 and 16 also selectively bound terpenoid compounds. In particular, the three SmosOBPs had high binding affinities (Ki < 20 mumol/L) to 3-hexanol and cis-3-hexenylacetate that elicited strong electroantennogram (EAG) response from female antennae. In addition, SmosOBP11 displayed significantly higher binding (Ki < 8 mumol/L) than SmosOBP16 and 21 to 1-octen-3-ol, D-panthenol, alpha-pinene and Heptyl acetate which elicited significant EAG response, suggesting that SmosOBP11 plays a major role in recognition and transportation of these volatiles. These findings have provided important insight into the molecular mechanism by which S. mosellana specifically recognizes plant volatiles for host selection, and have facilitated identification of effective volatile attractants that are potentially useful for pest monitoring and trapping.

Binding of aroma compounds with soy protein isolate in aqueous model: Effect of preheat treatment of soy protein isolate.[Pubmed:31000033]

Food Chem. 2019 Aug 30;290:16-23.

The interactions between flavors (hexyl acetate [HxAc], Heptyl acetate [HpAc], linalyl formate [LiFo], linalyl acetate [LiAc], geraniol, linalool, limonene and myrcene) and soy protein isolate (SPI) were investigated, the influence of flavors structure and preheated SPI (PSPI) were determined by using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) technology. For HxAc and HpAc, the binding of SPI and the flavors decreased in the order nature>80 degrees C>90 degrees C>100 degrees C PSPI, for LiFo, LiAc, geraniol, and linalool, nature<80 degrees C<90 degrees C<100 degrees C PSPI. For limonene and myrcene, an increase in headspace concentration or "salting out" effect was noticed. The NSPI (nature SPI) and PSPI of 80 degrees C showed two class binding sites for HxAc and HpAc. These results serve as a foundation for further investigation into the effect of preheating of SPI on its ability to bind to flavor-inducing compounds.

Ovicidal and larvicidal activity and possible mode of action of phenylpropanoids and ketone identified in Syzygium aromaticum bud against Bradysia procera.[Pubmed:29482729]

Pestic Biochem Physiol. 2018 Feb;145:29-38.

Bradysia procera is a serious insect pest of Panax ginseng plants. This study was conducted to determine the toxicity and mechanism of action of three phenylpropanoids, three terpenoids, and a ketone from Syzygium aromaticum bud methanol extract and hydrodistillate against third-instar larvae and eggs of B. procera. In a filter-paper mortality bioassay, methyl salicylate (LC50, 5.26mug/cm(2)) was the most toxic compound, followed by 2-nonanone, eugenol, and eugenyl acetate (8.77-15.40mug/cm(2)). These compounds were significantly less toxic than either thiamethoxam, clothianidin, or cypermethrin. Egg hatching was inhibited by 97, 85, and 40% at 11.7mug/cm(2) of methyl salicylate, 2-nonanone, and eugenol, respectively. The egg-hatching inhibition of these insecticides was between 90 and 94% at 0.09mug/cm(2). These constituents were consistently more toxic in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. The mechanism of larvicidal action of methyl salicylate, eugenol, and eugenyl acetate might be primarily due to interference with the octopaminergic system. 2-Heptyl acetate and 2-nonanone might act on both acetylcholinesterase and the octopaminergic receptor. 2-Heptanone might act primarily on acetylcholinesterase. Further studies will warrant possible applications of S. aromaticum bud-derived products as potential larvicides and ovicides for the control of B. procera.

Extended aroma extract dilution analysis profile of Shiikuwasha (Citrus depressa Hayata) pulp essential oil.[Pubmed:29389564]

J Food Drug Anal. 2018 Jan;26(1):268-276.

Shiikuwasha pulp is an important raw material for producing citrus essential oils. The volatile aroma composition of pulp essential oil was evaluated using gas chromatography (GC) methods, and its aroma profile was assessed using GC-olfactometry with an extended aroma extract dilution analysis (AEDA) technique in regard to alterations of odor strength and sensorial perception throughout serial dilution steps. The essential oil comprised a mixture of 55 aroma compounds, including monoterpene hydrocarbon, sesquiterpene hydrocarbon, alcohol, aldehyde, ester, and oxide compounds. The predominant compounds were limonene [57.36% (4462.80 mg/100 g of pulp)] and gamma-terpinene [25.14% (1956.21 mg/100 g of pulp)]. However, linalool was identified as one of the key aroma components providing the highest flavor dilution factor in AEDA, whilst three sesquiterpene hydrocarbons (delta-elemene, germacrene B, and bicyclosesquiphellandrene) and two esters (Heptyl acetate and decyl acetate) had superior relative flavor activities. The extended AEDA profile identified variations in assessed odor perceptions, intensity, and duration of aroma components over dilution, whereas the 12 most odor-active compounds showed comparable odor strengths.

Influence of the stereochemistry on the sensory properties of 4-mercapto-2-heptanol and its acetyl-derivatives.[Pubmed:23394583]

J Agric Food Chem. 2013 Mar 6;61(9):2062-9.

4-Mercapto-2-heptanol, previously described in cooked bell pepper, was used to determine the impact of the stereochemistry on the sensory properties of a thiol with a 1,3-oxygen-sulfur functionality. In addition, the acetyl-derivatives 4-acetylthio-2-heptanol, 4-mercapto-2-Heptyl acetate and 4-acetylthio-2-Heptyl acetate were investigated. The synthesized stereoisomers were separated via capillary gas chromatography (GC) using chiral stationary phases. The GC orders of elution were determined by assigning the absolute configurations via NMR analysis in combination with lipase-catalyzed kinetic resolutions. Odor thresholds and odor properties were determined by means of GC/Olfactometry. The data revealed that the sensory properties of the investigated compounds are not only significantly influenced by the acetylation but also by the configurations of the two asymmetric centers.