Ethyl phenylacetate

Characterization of the potent odorants in Tibetan Qingke Jiu by sensory analysis, aroma extract dilution analysis, quantitative analysis and odor activity values.[Pubmed:33233054]

Food Res Int. 2020 Nov;137:109349.

Tibetan Qingke Jiu is the most important alcoholic beverage in the daily life of Tibetan people due to its unique flavor and rich nutrients. In this study, the aromatic characteristics of Qingke Jiu were studied by sensory analysis, aroma extract dilution analysis (AEDA), quantitative analysis, and odor activity values (OAVs). Sensory evaluation demonstrated that Qingke Jiu had fruity, cooked potato, honey, sour, sweet, and caramel-like aroma. A total of 66 aroma compounds were identified by AEDA and gas chromatography-mass spectrometry, with flavor dilution (FD) factors ranging from 4 to 2048. Among them, methional, acetic acid, ethyl butanoate, phenylacetaldehyde and beta-phenylethanol appeared with the highest FD factors. The concentration of these aroma-active compounds was further quantitated by combination of four different quantitative measurements, and 17 odorants had concentrations higher than their odor thresholds. Based on the OAVs, phenylacetaldehyde, beta-phenylethanol, Ethyl phenylacetate, sotolon, furaneol, methional, methionol, gamma-nonalactone, ethyl 2-methylbutanoate, beta-damascenone, ethyl 3-methylbutanoate, ethyl acetate, ethyl butanoate, and acetic acid could be potentially important to the overall aroma profile of Qingke Jiu.

Evaluation of Perceptual Interactions between Ester Aroma Components in Langjiu by GC-MS, GC-O, Sensory Analysis, and Vector Model.[Pubmed:32069959]

Foods. 2020 Feb 13;9(2). pii: foods9020183.

Abstract: The volatile compounds of three Langjiu ("Honghualangshi, HHL", "Zhenpinlang, ZPL", and "Langpailangjiu, LPLJ") were studied by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 31, 30, and 30 ester compounds making a contribution to aroma were present in the HHL, ZPL, and LPLJ samples, respectively. From these esters, 16 compounds were identified as important odour substances, and their odour activity values (OAVs) were greater than 1. The key ester components were selected as: ethyl acetate, ethyl 2-methylbutyrate, ethyl 3-methyl butyrate, ethyl hexanoate, and Ethyl phenylacetate by aroma extract dilution analysis (AEDA), odour activity value (OAV), and omission testing. Five esters were studied for perceptual interactions while using Feller's additive model, OAV, and a vector model. Among these mixtures, they all have an enhancing or synergistic effect. Among these mixtures, one mixture presented an additive effect and nine mixtures showed a synergistic effect.

Characterization of the typical fragrant compounds in traditional Chinese-type soy sauce.[Pubmed:31874409]

Food Chem. 2020 May 15;312:126054.

In this work, a total of 35 important aroma compounds with odor activity values (OAVs) greater than 1 were detected by gas chromatography-mass spectrometry (GC-MS) in traditional Chinese-type soy sauce. Of these, fragrant compounds with aromatic rings (20 compounds) accounted for a large proportion, over 57%. Combining principal component analysis and GC-olfactometry-MS (GC-O-MS), 5-methyl-2-furanmethanethiol (OAV: 284-467), 3-methylbutanal (OAV: 409-938), phenylacetaldehyde (OAV: 47.4-566), 2-phenylethanol (OAV: 7.41-14.3), phenylethyl acetate (OAV: 7.00-18.1) and Ethyl phenylacetate (OAV: 12.7-21.3) were confirmed as the typical fragrant compounds among all samples. Furthermore, full two-dimensional gas mass spectrometry (GC x GC-TQMS) was applied and 414 aroma compounds were identified, which included another 85 fragrant compounds with aromatic rings.

Characterization of the aroma profile and key odorants of the Spanish PDO wine vinegars.[Pubmed:31855771]

Food Chem. 2020 May 1;311:126012.

The aroma profiles of Spanish wine vinegars with Protected Designation of Origin (PDO) were described and compared for the first time by gas chromatography-mass spectrometry-olfactometry (GC-MS-O), odor-active values (OAVs) and quantitative descriptive analysis (QDA). Vinagre de Jerez Reserva (JRE) showed higher percentage of 'grassy-vegetal' impact odorants, while 'spicy' compounds highlighted the Pedro Ximenez category (JPX). Vinagre de Montilla-Moriles Reserva (MRE) had 'buttery-lactic' impact odorants, while 'empyreumatic' and 'sweet' aromas stood out for Pedro Ximenez category (MPX). Vinagre de Condado de Huelva Reserva (CRE) showed a stronger percentage of 'chemical' impact odorants. The key odorants were ethyl propionate, ethyl octanoate, propanoic acid and 4-ethylphenol for JRE, diacetyl and methional/furfural for JPX, acetoin for MRE, Ethyl phenylacetate and vanillin for MPX and acetaldehyde diethyl acetal, isobutyl acetate, ethyl isovalerate and guaiacol for CRE. A good relation among the impact odorants and the sensory descriptors was observed.

Alcohol acyltransferase gene and ester precursors differentiate composition of volatile esters in three interspecific hybrids of Vitis labruscaxV. Vinifera during berry development period.[Pubmed:31174754]

Food Chem. 2019 Oct 15;295:234-246.

This study investigated the accumulation of esters in three hybrid grape cultivars during berry development under two vintages to elucidate the differentiation on their esters biosynthesis. Results showed 'Moldova' showed lower esters content than 'Campbell Early' and 'Catawba' resulting from its limited AAT gene expression and 20 different encoded amino acids. The volatile esters compositions of 'Campbell Early' and 'Catawba' in both vintages were different. Correlation analysis revealed that concentrations of hexyl acetate, 2-phenethyl acetate, ethyl (E,E)-2,4-hexadienoate and Ethyl phenylacetate were related to their corresponding alcohols level, whereas threonine and alanine affected ethyl heptanoate formation. Transcriptome analysis indicated that 1847, 1781 and 1870 DEGs, at E-L 35, 36 and 38, respectively, were characterized between 'Campbell Early' and 'Catawba'. The expression level of genes related to the volatile ester precursors biosynthesis, including PRX-VIT_211s0016g05320, PAO-VIT_217s0000g09100, ACOX-VIT_212s0028g02660, ACOX-VIT_216s0022g01120, echA-VIT_205s0077g00860 and ACOX-VIT_200s0662g00010, exhibited a positive correlation to the concentrations of their corresponding volatile esters.

Characterization of key aroma compounds in Chinese rice wine using gas chromatography-mass spectrometry and gas chromatography-olfactometry.[Pubmed:31151652]

Food Chem. 2019 Sep 30;293:8-14.

To determine the key aroma compounds in Chinese rice wine (CRW), four types of CRW (YH, JF, SN, and XX) were analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and sensory evaluation. The contributions of the key aroma compounds to the flavor characteristics were determined by partial least squares regression. Sixty-one aroma compounds were detected. Twenty-five components were identified as odor-active compounds. On the basis of their odor active values, 18 odor-active compounds were determined as key aroma compounds. Ethyl isovalerate, ethyl butyrate, ethyl acetate, ethyl hexanoate, and phenylethyl alcohol were key aroma compounds in all four types of wine. The unique key aroma compounds of JF wine were isovaleraldehyde and isoamyl acetate; those of XX wine were 1-butanol, benzaldehyde, ethyl benzoate, Ethyl phenylacetate, 2-octanone, and furfural; that of YH wine was ethyl 2-methylbutyrate; and those of SN wine were 1-butanol, 1-hexanol, 2-butenoic acid ethyl ester, and 3-methyl-1-butanol.

Odorants quantitation in high-quality cocoa by multiple headspace solid phase micro-extraction: Adoption of FID-predicted response factors to extend method capabilities and information potential.[Pubmed:30685038]

Anal Chim Acta. 2019 Apr 4;1052:190-201.

This paper focuses on several methodological aspects in the quantitation of volatiles in solid samples by headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography and parallel detection by flame ionization detector and mass spectrometry (GC-FID/MS). Informative volatiles, including key odorants and process markers, from single-origin cocoa samples (Colombia, Ecuador, Mexico, Sao Tome, and Venezuela) were captured at two processing stages along the chocolate production chain (nibs and cocoa mass). Accurate quantitation was achieved by multiple headspace extraction (MHE) in headspace linearity conditions and by external calibration. Quantitative results on selected analytes (3-hydroxy-2-butanone, 2-heptanol, 2,3,5-trimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, ethyl octanoate, benzaldehyde, 2-methylpropionic acid, 3-methylbutyric acid, Ethyl phenylacetate, 2-phenylethyl acetate, guaiacol, 2-phenylethanol, and (E)-2-phenyl-2-butenal) provided reliable information about the key sensory notes of cocoa intermediates (odor activity values) and their origin specificities. Additional information about analytes release by the solid environment (cocoa nibs, mass, and powders) was achieved by modeling decay curves. Parallel detection by MS and FID enabled quantitative cross-validation, and FID-predicted relative response factors (RRFs) extended method quantitation capabilities to additional compounds that were not subjected to an external calibration procedure: 3-methylbutyl acetate (isoamyl acetate), 2-heptanone, heptanal, 2-nonanone, gamma-butyrolactone, octanoic acid, 2-ethyl-5(6)-methylpyrazine, phenylacetic acid, phenol, 2-acetyl pyrrole, and 2,3-dihydro-3,5-dihydroxy-6-methyl(4H)-pyran-4-one. This procedure extends method capabilities and information potential with great consistency.

Bioformation of Volatile and Nonvolatile Metabolites by Saccharomycopsis fibuligera KJJ81 Cultivated under Different Conditions-Carbon Sources and Cultivation Times.[Pubmed:30366381]

Molecules. 2018 Oct 25;23(11). pii: molecules23112762.

Saccharomycopsis fibuligera KJJ81 isolated from nuruk is an amylolytic yeast that is widely used as a microbial starter in various fermented foods. Volatile and nonvolatile metabolites of S. fibuligera KJJ81 were investigated according to different carbon sources and cultivation times using a nontargeted metabolomic approach. Partial-least-squares discriminant analysis was applied to determine the major metabolites, which were found to be closely related to the clustering and discrimination of S. fibuligera KJJ81 samples. Some volatile metabolites derived from phenylalanine, such as 2-phenylethanol, 2-phenylethyl acetate, and Ethyl phenylacetate, were predominantly found in cultivation medium containing glucose (YPD medium). In addition, the level of 2-phenylethanol increased continuously with the cultivation time. In terms of nonvolatile metabolites, carbohydrates (mannose, arabitol, and mannitol), fatty acids (palmitic acid and stearic acid), organic acids (oxalic acid and succinic acid), and amino acids (isoleucine, serine, alanine, glutamic acid, glycine, proline, phenylalanine, and threonine) were the main contributors to S. fibuligera KJJ81 samples cultivated in YPD medium according to cultivation time. These results show that the formation of volatile and nonvolatile metabolites of S. fibuligera KJJ81 can be significantly affected by both the carbon sources and the cultivation time.

Sensory evaluation of the synergism among ester odorants in light aroma-type liquor by odor threshold, aroma intensity and flash GC electronic nose.[Pubmed:30195503]

Food Res Int. 2018 Nov;113:102-114.

Although esters were important odorants in light aroma-type liquor, it was still puzzling that sensory interaction between esters made the odor quality of light aroma-type liquor outstanding. The aim of the paper was to investigate perceptual interaction among esters. The odor thresholds of eighteen esters and 35 binary mixture were determined by a three-alternative forced-choice procedure. The relationship between odor threshold and carbon chain length of homologous ethyl esters was investigated. Moreover, 31 binary mixtures present either a synergistic effect or additive action. Furthermore, odor quality and odor intensity were determined by p/tau plot and sigma/tau plot, respectively. From the p/tau plot, an ideal sigmoidal function for odor quality was obtained. From the sigma/tau plot, for all 120 binary mixtures, just 9 mixtures were in the hyper-additivity area (sigma>1.05), and two were in the so-called perfect additivity area (0.95Ethyl phenylacetate at various levels (100, 2500, 58,000ppb) to the fruit recombination and an enhancement effect of floral note was reported by adding phenylethyl acetate at low (1400ppb) or high level (11,500ppb). It was noticed that sweet note was significantly enhanced by adding phenylethyl acetate at peri-threshold (3200ppb).

Antifungal Activity of Natural Volatile Organic Compounds against Litchi Downy Blight Pathogen Peronophythora litchii.[Pubmed:29419754]

Molecules. 2018 Feb 8;23(2). pii: molecules23020358.

Litchi (Litchi chinensis Sonn.) is a commercially important fruit but its production and quality are restricted by litchi downy blight, caused by the oomycete pathogen Peronophythora litchii Chen. Volatile substances produced by a biocontrol antinomycetes Streptomyces fimicarius BWL-H1 could inhibited P. litchii growth and development both in vitro and in detached litchi leaf and fruit infection assay. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses indicated that volatile organic compounds (VOCs) from BWL-H1 resulted in severe damage to the endomembrane system and cell wall of P. litchii cells in vitro and abnormal morphology of appressoria, as well as deformed new hyphae in infection process. VOCs could suppress mycelial growth, sporulation, while with no obvious effect on sporangia germination. Based on gas chromatography-mass spectrophotometric analyses, 32 VOCs were identified from S. fimicarius BWL-H1, the most abundant of which was phenylethyl alcohol. Eight VOCs, including phenylethyl alcohol, Ethyl phenylacetate, methyl anthranilate, alpha-copaene, caryophyllene, humulene, methyl salicylate and 4-ethylphenol, that are commercially available, were purchased and their bioactivity was tested individually. Except for humulene, the other seven tested volatile compounds shown strong inhibitory activity against mycelial growth, sporulation, sporangia germination and germ-tube growth of P. litchii. Especially, 4-ethylphenol showed the highest inhibitory effect on sporulation at a very low concentration of 2 microL/L. Overall, our results provided a better understanding of the mode of action of volatiles from BWL-H1 on P. litchii, and showed that volatiles from BWL-H1 have the potential for control of postharvest litchi downy blight.

Tuning Chocolate Flavor through Development of Thermotolerant Saccharomyces cerevisiae Starter Cultures with Increased Acetate Ester Production.[Pubmed:26590272]

Appl Environ Microbiol. 2015 Nov 20;82(2):732-46.

Microbial starter cultures have extensively been used to enhance the consistency and efficiency of industrial fermentations. Despite the advantages of such controlled fermentations, the fermentation involved in the production of chocolate is still a spontaneous process that relies on the natural microbiota at cocoa farms. However, recent studies indicate that certain thermotolerant Saccharomyces cerevisiae cultures can be used as starter cultures for cocoa pulp fermentation. In this study, we investigate the potential of specifically developed starter cultures to modulate chocolate aroma. Specifically, we developed several new S. cerevisiae hybrids that combine thermotolerance and efficient cocoa pulp fermentation with a high production of volatile flavor-active esters. In addition, we investigated the potential of two strains of two non-Saccharomyces species that produce very large amounts of fruity esters (Pichia kluyveri and Cyberlindnera fabianii) to modulate chocolate aroma. Gas chromatography-mass spectrometry (GC-MS) analysis of the cocoa liquor revealed an increased concentration of various flavor-active esters and a decrease in spoilage-related off-flavors in batches inoculated with S. cerevisiae starter cultures and, to a lesser extent, in batches inoculated with P. kluyveri and Cyb. fabianii. Additionally, GC-MS analysis of chocolate samples revealed that while most short-chain esters evaporated during conching, longer and more-fat-soluble ethyl and acetate esters, such as ethyl octanoate, phenylethyl acetate, Ethyl phenylacetate, ethyl decanoate, and ethyl dodecanoate, remained almost unaffected. Sensory analysis by an expert panel confirmed significant differences in the aromas of chocolates produced with different starter cultures. Together, these results show that the selection of different yeast cultures opens novel avenues for modulating chocolate flavor.

Aroma compounds in Ontario Vidal and Riesling icewines. I. Effects of harvest date.[Pubmed:28455036]

Food Res Int. 2015 Oct;76(Pt 3):540-549.

Icewine is a sweet dessert wine made from pressing grapes naturally frozen on the vines. It is likely that freeze/thaw cycles endured by icewine grapes change their chemical and sensory profiles due to climatic events. Our objective was to determine the influence of harvest date on icewine must and wine basic chemical variables and aroma compounds. Riesling and Vidal icewines were made from grapes picked between December 2004 and February 2005; Harvest 1 (H1): 19 December; Harvest 2: 29 December; Harvest 3 (H3): 18 January; and Harvest 4 (H4): 11 February (Vidal only). Icewine musts differed in titratable acidity and pH (Vidal only). All basic wine chemical analytes differed across harvest dates. All aroma compounds differed in Vidal and Riesling wines. Highest concentrations for most aroma compounds were in the last harvest date; 16 of 24 for Vidal and 17 of 23 for Riesling. The latest harvest date had highest ethyl isobutyrate, ethyl 3-methylbutyrate, 1-hexanol, 1-octen-3-ol, 1-octanol, cis-rose oxide, nerol oxide, ethyl benzoate, Ethyl phenylacetate, gamma-nonalactone and beta-damascenone. H1 had highest ethyl butyrate, ethyl hexanoate, linalool, 4-vinylguaiacol and ethyl octanoate. Based on odor activity values, the most odor-potent compounds were beta-damascenone, cis-rose oxide, 1-octen-3-ol, ethyl octanoate, ethyl hexanoate, and 4-vinylguaiacol across harvest dates. PCA found most aroma compounds associated with the last harvest date, 4-vinylguaicol excepted, which was associated with H1. Harvest date was considered a discriminating dimension using canonical variant analysis for volatile compounds.

[Study on secondary metabolites of endophytic fungi Penicillium polonicum].[Pubmed:25751949]

Zhongguo Zhong Yao Za Zhi. 2014 Oct;39(20):3974-7.

The PDB culture medium was selected to ferment the endophyte strain, and the secondary metabolites of endophytic fungi Penicillium polonicum were studied. Combined application of Sephadex LH-20, ODS and HPLC chromatographies over the ethyl acetate extract of the fermented culture led to the isolation of 6 compounds. By spectral methods, the structures were elucidated as [3, 5-dihydroxy-2-(7-hydroxy-octanoyl)]-ethylphenylacetate (1), (3, 5-dihydroxy-2- octanoyl)-Ethyl phenylacetate (2), (5, 7-di- hydroxy-9-heptyl)-isobenzo pyran-3-one (3), 3-(hydroxymethyl) 4-(1E)-1- propen-1-yl-(1R, 2S, 5R, 6S)-7-oxabicyclo [4.1.0] hept-3-ene-2, 5-diol (4), (E)-2-methoxy-3-(prop-1-enyl) phenol (5) and p-hydroxylphenylethanol (6).