Phenethyl Acetate Research Articles

Effect of multi‐step chaptalisation on physicochemical properties, potentially harmful alcohols, nutritional composition and volatile profiles of kiwi wine

SummaryChaptalisation is commonly used to ameliorate the potential alcohol of kiwi wine prior to fermentation. It can be performed either by one‐time sugaring or via multiple supplementations of sugar. However, for both approaches, their precise effects on chemical composition of kiwi wine are unclear. Thus, this study evaluated the influence of five different multi‐step chaptalisation strategies on physicochemical parameters, potentially harmful alcohols, nutritional composition and volatile compounds of kiwi wine. Results show that multi‐step chaptalisation significantly reduced total acidity and harmful alcohols of the resulting kiwi wine. Among the harmful alcohols, the greatest reduction was seen for isoamyl alcohol and isobutanol. Additionally, multi‐step chaptalisation also modified volatile profile of the kiwi wine, particularly in acetate esters (isoamyl acetate and phenethyl acetate), ethyl esters, n‐octanal and decanal. Together, our results highlight the potential of using multi‐step chaptalisation to produce ‘healthier’ kiwi wines with more balanced alcohol and more complexed flavour.

Effect of DAP and glutamine supplementation on sulfur-containing volatiles and sensory properties of Chardonnay wine fermented with Saccharomyces cerevisiae yeast.

Volatile compounds in wine have a critical impact on the consumers' senses. In this study, the effect of diammonium phosphate (DAP) and glutamine on sulfur-containing volatiles and sensory properties of Chardonnay wine fermented with Saccharomyces cerevisiae yeast were evaluated. Fermentation kinetics was determined by monitoring reducing sugar consumption rates during fermentation. The volatile profile of wines was analyzed by headspace solid phase microextraction (HS-SPME) coupled with gas-chromatography-mass spectrometry (GC-MS). The volatile sulfur compounds (VSCs) were analyzed by HS-SPME-GC-MS/MS. Flavor attributes of wines were assessed by a sensory panel with quantitative descriptive analysis. A total of 53 volatiles, including 6 VSCs, were identified and quantified in the Chardonnay wine. The results suggested that glutamine supplementation at the beginning of fermentation could help to initiate fermentation earlier and promote the formation of isoamyl acetate, phenethyl acetate, ethyl nonanoate, methyl decanoate, diethyl succinate and phenethyl alcohol, isobutanol, while DAP supplementation had no obvious effect on the volatile composition of the resulting wine and fermentation kinetics. PRACTICAL APPLICATION: Suitable nitrogen source is helpful to a healthy fermentation, and can also prevent the off-flavor and regulate aroma profile of wine. This study provides insights on the volatile and sensory characteristics of Chardonnay wines affected by different nitrogen source addition.

Analyzing Volatile Compounds of Young and Mature Docynia delavayi Fruit by HS-SPME-GC-MS and rOAV.

This study focused on the examination of the volatile compounds and fragrance properties of the young and mature fruit of Docynia delavayi. Headspace solid-phase microextraction combined with gas chromatography−mass spectrometry (HS-SPME-GC-MS) was applied for identifying 42 volatile compounds, with young and mature fruit containing 36 and 42 compounds, respectively. Heat map cluster analysis, principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA), and independent sample t-testing were used to analyze sample differences. Based on a variable importance in projection (VIP) > 1 and p < 0.05, 23 key volatile compounds such as octanal, geranylacetone, butyl acetate, and dihydro-β-ionone were screened. β-Ionone and phenethyl acetate made the largest contribution to the aroma of D. delavayi after analyzing the relative odor activity value (rOAV) of the key volatile compounds and their aroma descriptors. Young D. delavayi fruit exhibited a prominent woody scent, while mature D. delavayi fruit had more intense floral and rosy aromas. The findings may lay a foundation for comprehensively developing and utilizing D. delavayi fruit.

Insights into Characteristic Volatiles in Wuyi Rock Teas with Different Cultivars by Chemometrics and Gas Chromatography Olfactometry/Mass Spectrometry.

Wuyi rock tea (WRT) is one of the most famous subcategories of oolong tea, exhibiting distinct aroma characteristics with the application of different cultivars. However, a comprehensive comparison of the characteristic volatiles among WRTs with different cultivars has rarely been carried out. In this study, non-targeted analyses of volatile fragrant compounds (VFCs) and targeted aroma-active compounds in WRTs from four different cultivars were performed using chemometrics and gas chromatography olfactometry/mass spectrometry (GC-O/MS). A total of 166, 169, 166, and 169 VFCs were identified for Dahongpao (DHP), Rougui (RG), Shuixian (SX), and Jinfo (JF), respectively; and 40 components were considered as the key differential VFCs among WRTs by multivariate statistical analysis. Furthermore, 56 aroma-active compounds were recognized with predominant performances in "floral & fruity", "green & fresh", "roasted and caramel", "sweet", and "herbal" attributes. The comprehensive analysis of the chemometrics and GC-O/MS results indicated that methyl salicylate, p-cymene, 2,5-dimethylpyrazine, and 1-furfurylpyrrole in DHP; phenylethyl alcohol, phenethyl acetate, indole, and (E)-β-famesene in RG; linalool, phenethyl butyrate, hexyl hexanoate, and dihydroactinidiolide in JF; and naphthalene in SX were the characteristic volatiles for each type of WRT. The obtained results provide a fundamental basis for distinguishing tea cultivars, recombination, and simulation of the WRT aroma.

Use of Kombucha SCOBY and Commercial Yeast as Inoculum for the Elaboration of Novel Beer

Kombucha is a beverage obtained from fermentation of Camellia sinensis tea using a symbiotic culture of bacteria and yeast (SCOBY). This association of bacteria and yeasts can be an interesting source of microorganisms for developing fermented beverages, including beer. The objective of this study was to evaluate kombucha SCOBY and commercial brewing yeast as a starter culture for the elaboration of beer. Three assays were performed to develop the beverage (C = control, KL = kombucha + yeast, K = kombucha). The pH, density, carbohydrates, organic acids and ethanol were evaluated during fermentation. Microbial counts (yeasts and mesophilic bacteria) and volatile compounds were recorded at the initial and final fermentation times. The content of total phenolic compounds, antioxidant capacity, color and bitterness (IBU) of the beers were determined. The results showed that kombucha-fermented wort produces a beer with differentiated characteristics. Increased lactic acid (0.73 g/L) and low alcohol content (1.3%) were observed in the K assay. Further, desired volatile compounds, such as ethyl octanoate, phenethyl acetate and 2-phenylethanol, were also found in this beer. The combination of kombucha and commercial yeast for beer production showed carbohydrate consumption and contents of organic acids similar to those of control beer, producing beers with an alcohol content of 5.9%. From the results, it was possible to observe a tendency for the content of total phenolic compounds (37.57, 33.00 and 31.64 mg/100 mL for K, KY and C assays, respectively) to increase when the wort was inoculated with kombucha. There was no difference in the antioxidant activity of the produced beers. All produced beers showed a yellowish color and a bitterness value (IBU) of 27%. The present study showed that adding kombucha as a starter culture produced beer with differentiated properties, such as high antioxidant activity, low alcohol content and sour characteristics.

Chemical and Sensory Characteristics of Different Red Grapes Grown in Xinjiang, China: Insights into Wines Composition

Globally, the red wine market experienced a rapid growth in the last decade, due to the superior colour, taste, and nutritional quality. The red grapes used for vinification have individual characteristics varying within the regional environment. In this study, the quality of seven grape cultivars, including Marselan, Yan 73, Muscat Hamburg, Kadarka, Merlot, Cabernet Sauvignon, and Crimpose, and their corresponding wines, were investigated based on high-performance liquid chromatography and headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry. These techniques were performed to analyze the chemical compositions and volatile compounds of the tested samples, respectively. The results showed that tartaric acid (29.96% to 73.45%) and rutin (12.53% to 56.54%) were the dominant organic acid and phenolic compounds in grapes, respectively. Higher concentrations of organic acids and phenolic compounds, and the types of volatile compounds, were observed to be highest in the Cabernet Sauvignon grape. The antioxidant activity of wines ranged from 6.74 to 102.68 mmol TE/L, and Yan 73 wine had the highest antioxidant activity. A total of 69 volatile compounds consisting of 17 alcohols, 26 esters, 5 aldehydes, 9 acids, 7 ketones, and 5 other volatile compounds were identified in all tested wines, and 11 important aroma active substances (odor activity value &gt; 1) were selected, consisting of β-ionone, phenethyl acetate, geranyl acetate, ethyl 9-decenoate, ethyl caprate, ethyl pelargonate, decanal, ethyl caprylate, 6-methyl-5-hepten-2-one, methyl 2-hexenoate, and ethyl hexanoate, which endow wines with a unique aroma. This work clearly describes the chemical and sensory characteristics of seven red grape cultivars in Xinjiang of China and provides diversity options for cultivars for winemaking.

Increase the Content of Ester Compounds in Blueberry Wine Fermentation with the Ester-Producing Yeast: Candida glabrata, Pichia anomala, and Wickerhamomyces anomalus.

The co-fermentation of Saccharomyces cerevisiae and ester-producing yeasts is considered to be an effective way to improve the flavor and quality of fruit wine. In this study, three kinds of ester-producing yeasts (Candida glabrata NCUF308.1, Pichia anomala NCUF306.1, and Wickerhamomyces anomalus NCUF307.1) and S. cerevisiae NCUF309.2 were used to simulate blueberry wine co-fermentation at different ratios. The results showed that, compared with S. cerevisiae NCUF309.2 fermentation (S), the population of S. cerevisiae NCUF309.2 in co-fermentation samples decreased to varying degrees, and the content of ethanol also decreased. The results also showed that the co-fermentation of C. glabrata NCUF308.1 and S. cerevisiae NCUF309.2 at the ratio of 1:1 (CS1), co-fermentation of P. anomala NCUF306.1 and S. cerevisiae NCUF309.2 at the ratio of 5:1 (PS5), and co-fermentation of W. anomalus NCUF307.1 and S. cerevisiae NCUF309.2 at the ratio of 5:1 (WS5) could significantly increase the content of ester compounds (p &lt; 0.05), which was 3.29, 4.75, and 3.04 times that of the S sample, respectively. Among them, the sample of CS1 was characterized by phenethyl acetate and isoamyl acetate, while the samples of CS5 and PS5 were characterized by propyl octanoate and ethyl decanoate, and the sample of WS5 was characterized by 3-methylbutyl hexanoate. However, the contents of odor active compounds were higher in the CS1 sample. Therefore, the samples of CS1 had the potential to create the distinctive flavor of blueberry wine.

Fruit Wine Obtained from Melon by-Products: Physico-Chemical and Sensory Analysis, and Characterization of Key Aromas by GC-MS.

About 20% of fresh fruits and vegetables are rejected for not meeting the superficial aesthetic standards (color, shape, and size). Part of the food production is not used in the human food chain. The transformation of these fresh products into novel re-valuable ones is a challenge for a sustainable food industry. This research studies an alcoholic fermentation fruit-based wine from two melon (Cucumis melo L.) cultivars: Jimbee® (smooth and yellow skin with orange flesh) and Okashi® (netted yellow-orange skin with pale green flesh). The melon juice (must) was fermented by Saccharomyces cerevisiae and enriched in sucrose and organic acids to achieve alcoholic fermentation, acidity, and flavors, obtaining a fruity-flavored and dry melon-based wine with 10° alcoholic grade, in both melon cultivars. The volatile compounds were measured by GC-MS and the odor activity value (OAV) was calculated. The Jimbee and Okashi melon wines increased their aromatic profile due to an increment in medium-chain fatty acid ethyl esters such as ethyl hexanoate, ethyl octanoate, and ethyl decanoate (OAV &gt; 1), which contributed to the fruity aroma. Other volatile compounds such as ethyl 9-decenoate and phenethyl acetate (OAV &gt; 1) appeared in the Okashi wine, which brought a floral aroma. For sensory evaluation (40-100), the Jimbee cultivar, with its orange flesh, scored 68.2 and the Okashi cultivar, with pale green flesh, scored 82.8, which was the preferred melon-based wine. This is an example of a circular economy model to produce a fruit-based wine with commercial potential and satisfactory sensory evaluation.

Dynamic changes of quality and flavor characterization of Zhejiang rosy vinegar during fermentation and aging based on untargeted metabolomics

Zhejiang Rosy Vinegar (ZRV) is a traditional condiment in Southeast China. This study aimed to track the physicochemical, microbiological, sensory changes, and metabolomic profiles of ZRV during fermentation and aging. The increase of acidity and decrease of reducing sugar were associated with the dominant growth of Lactobacillus and Acetobacter. The total 35 volatile compounds were identified in ZRV, mainly containing alcohols, esters, acids, aldehydes, ketones acids, phenols and nitrogen-containing. Compared to phenethyl acetate with sweet aroma in fresh vinegar, the compound with high odor activity values was isoamyl acetate with fruity aromas in aged vinegar. Furthermore, 1309 types of non-volatile components were identified, and histidine metabolism and arginine biosynthesis were revealed as main pathways during fermenting and aging. Concurrently, various bioactive substances in ZRV were identified. This study enriched the knowledge on the components and flavor of ZRV, and assist to improve the production quality of vinegar.

Using wild yeasts to modulate the aroma profile of low-alcoholic meads.

In recent years, ample research has focused on applying wild (especially non-Saccharomyces) yeasts in producing alcoholic beverages. Common characteristics of wild yeast strains include simultaneous high production of fruity and floral aroma compounds and low ethanol production. In this study, mead starter cultures were selected based on preliminary screening of wild yeast strains from a Brazilian culture collection (n = 63) for their ability to produce aroma-active compounds. The selected strains included one strain of Saccharomyces cerevisiae and three non-Saccharomyces strains (Pichia jadinii, Torulaspora delbrueckii, and Kluyveromyces lactis). These strains were used to ferment honey must prepared with Aroeira honey, adjusted to 24°Brix, which took 36days to complete. Single culture fermentations and co-fermentations with S. cerevisiae and non-Saccharomyces strains were carried out. The quality of the produced beverages was evaluated by sugar consumption and production of alcohols and organic acids, analyzed with high-performance liquid chromatography. The volatile organic compound composition was analyzed with gas chromatography-mass spectrometry. Meads with various ethanol amounts (4.7-11.0% v/v) and residual sugar contents (70.81-160.25gl-1) were produced. In addition, in both single-strain fermentation and co-fermentation with S. cerevisiae, meads produced with either Torulaspora delbrueckii or Kluyveromyces lactis had a roughly three-fold higher content of honey-aroma compound phenethyl acetate and a higher hedonic impression score than meads produced with only S. cerevisiae. These results demonstrated non-Saccharomyces yeasts' ability to increase aroma complexity and improve the sensory quality of low-alcoholic meads.

Honeycomb, a New Food Resource with Health Care Functions: The Difference of Volatile Compounds found in Apis cerana and A. mellifera Honeycombs

The honeycomb composition is very complex, containing honey, royal jelly, pollen, and propolis, and thus contains a large number of bioactive ingredients, such as polyphenols and flavonoids. In recent years, honeycomb as a new functional food resource has been favored by many bee product companies, but the basic research on honeycomb is lacking. The aim of this study is to reveal the chemical differences between A. cerana honeycombs (ACC) and A. mellifera honeycombs (AMC). In this paper, we studied the volatile organic components (VOCs) of ACC and AMC by solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). A total of 114 VOCs were identified in 10 honeycombs. Furthermore, principal component analysis (PCA) revealed that the chemical composition of ACC and AMC were different. Additionally, orthogonal partial least squares discrimination analysis (OPLS-DA) revealed that benzaldehyde, octanal, limonene, ocimene, linalool, α-terpineol, and decanal are the significant VOCs in AMC extracts, which are mainly derived from propolis. OPLS-DA model also identified 2-phenylethanol, phenethyl acetate, isophorone, 4-oxoisophorone, betula, ethyl phenylacetate, ethyl palmitate, and dihydrooxophorone as potential discriminatory markers of ACC, which likely contribute to protecting the hive against microorganisms and keep it clean.

Comparative analysis of sugar, acid, and volatile compounds in CPPU-treated and honeybee-pollinated melon fruits during different developmental stages

Plant growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) is widely used in fruit production. However, the mechanism in which CPPU affects melon fruit quality, especially aroma compound, remains unclear. Here, gas chromatography–mass spectrometry was performed to detect the sugar, citric acid, and aroma content in CPPU-treated and pollinated melon fruit. Results showed that the application of CPPU decreased the sugar and aroma content in melon fruit. The relative content of several important esters, including isobutyl acetate, ethyl acetate, 2-methylbutyl acetate, methyl acetate, benzyl acetate, and phenethyl acetate, in CPPU-treated fruits was significantly lower than that in honeybee-pollinated fruits. The content of many amino acids (isoleucine, leucine, valine, methionine, and l-phenylalanine), which could be metabolized into aroma compounds, in CPPU-treated fruits was significantly higher than that in honeybee-pollinated fruits. In conclusion, CPPU application interferes with amino-acid metabolism and affects the production of aromatic esters in melon fruit.

Chocolates with Brazilian cocoa: Tracking volatile compounds according to consumers’ preference

This study aimed to evaluate the volatile compounds of chocolates made of Brazilian cocoas and statistically track them according to the products’ sensorial profile in order to relate them to consumers’ acceptance by preference map methodology. The intensity of the chocolate, acidity, woody, smoked, green, floral, burned, musty, and cocoa notes from chocolates produced with cocoa from different Brazilian states were analyzed by a trained panel and by 128 consumers. Samples from Côte d’Ivoire, which is known for its high-quality chocolate, were evaluated for comparison. Solid-phase microextraction headspace sampling/gas chromatography-mass spectrometry was employed to evaluate the samples’ volatile compounds. One hundred volatile compounds were identified within the samples. The results from the preference maps showed that the maximum preference was found for chocolate made of cocoa from Rondônia, Bahia, and Espírito Santo and Côte d’Ivoire and organic samples from Pará. The ideal sample point was characterized by intense chocolate, floral, and woody notes and mild green and burned notes. The presence of furfural, 3-methyl butanal, phenethyl acetate, 2-phenyl-5-methyl-2-hexenal, methyl pyrazine, phenethyl acetate, 2-phenyl-5-methyl-2-hexenal, and tetramethyl pyrazine were shown to be important for consumer acceptance in the ideal product, whereas the presence of (Z)-2-heptenal and 2-pentyl furan may increase consumer rejection. 2,3-Methyl pyrazine, methyl pyrazine, and 2,3-butanediol, which are important volatile compounds previously reported in the literature, were statistically tracked to both positive and negative sample attributes and must be better explored concerning consumers’ acceptance of chocolates.

Detection of spoilage-causing yeasts and bacteria in tchapalo, the Ivorian traditional sorghum beer.

In this study, we aimed to analyse the spoilage potential of the isolated yeast, LAB and AAB species. Thus, 11 strains were inoculated at 0·3% (v/v) into a sterile filtered tchapalo and stored for 3 days at ambient temperature (27-30°C). All the tested strains grew well or remained stable except for Limosilactobacillus fermentum and Pediococcus acidilactici, which decreased throughout the storage time. A significant decrease of total soluble solids was observed only for Saccharomyces cerevisiae (from 7·8 to 5·8 °Brix) and Meyerozyma guilliermondii (from 7·8 to 5·5 °Brix). The tchapalo samples inoculated with the LAB strains Weissella paramesenteroides, P. acidilactici, L. fermentum and the yeast strain Candida tropicalis were judged similar to the control by the panellists. However, the strains of Lacticaseibacillus paracasei and Latilactobacillus curvatus (LAB), S. cerevisiae, M. guilliermondii and Kluyveromyces marxianus (yeasts) and Acetobacter pasteurianus and A. cerevisiae (AAB) induced the spoilage of the tchapalo appearance, smell and/or taste. In the spoiled tchapalo quantitative and qualitative modification of some volatile compounds (VOCs), such as lilac aldehyde, ethyl acetate, ethyl hexanoate, ethyl octanoate and phenethyl acetate, were observed. These results provide information about the microorganisms that need to be removed to extend the shelf life of tchapalo.

A Snapshot of Microbial Succession and Volatile Compound Dynamics in Flat Peach Wine During Spontaneous Fermentation.

Flat peaches possess characteristic flavors and are rich in nutrients. The fermentation of flat peaches to produce wine through complex biochemical reactions is an effective method to overcome their seasonal defects. Spontaneously fermented flat peach wine has plentiful and strong flavors, but the microbiota of fermentation are still unknown. In this study, the microbial succession and volatile compound dynamics of spontaneous fermentation in Xinjiang flat peach wine were investigated using high-throughput sequencing (HTS) and headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) technology, respectively, to better understand the microbiota involved. Multivariate data analysis was used to predict the relationship between microorganisms and volatile chemicals. The results showed that Kazachstania, Pichia, Aspergillus, Fructobacillus, Leuconostoc, and Lactobacillus were the dominant genera during the spontaneous fermentation of flat peach wine. Furthermore, ethyl hexanoate, 3-hexen-1-yl acetate, ethyl caprate, ethyl caprylate, phenethyl acetate, ethanol, γ-decalactone, decanal, 1-hexanoic acid, and octanoic acid endued flat peach wine with a strong fruity and fatty aroma. The core functional microbiota (primarily consisting of 11 bacterial and 14 fungal taxa) was strongly associated with the production of 27 volatile compounds in the spontaneously fermented flat peach wine, according to multivariate data analysis. Some alcohols and esters were positively linked with the presence of Kazachstania and Pichia. Meanwhile, the presence of Fructobacillus, Leuconostoc, Lactobacillus, and Weissella was significantly correlated with 2-non-anol, ethanol, 3-methyl-1-butanol, octyl formate, isoamyl lactate, and ethyl lactate. This snapshot of microbial succession and volatile compound dynamics provides insights into the microorganisms involved in flat peach wine fermentation and could guide the production of flat peach wine with desirable characteristics.

The impact of indigenous Saccharomyces cerevisiae and Schizosaccharomyces japonicus on typicality of crystal grape (Niagara) wine

Schizosaccharomyces japonicus have been found as dominant yeast species coexisting with Saccharomyces cerevisiae during late stages of spontaneous fermentation of local grapes in Guizhou, China. Therefore, this study further investigated the impacts of the two indigenous yeast species on typicality of crystal grape (Niagara) wine. Five indigenous and one commercial S. cerevisiae strains were firstly selected based on their genotypes and fermentation traits in synthetic medium. All the six S. cerevisiae exhibited high tolerance to glucose, temperature, and SO2. The two killer active strains FBKL2.996 and FBKL2.9126 showed relative higher tolerance capacity of ethanol, pH and osmotic pressure than the other four S. cerevisiae strains. Further pure fermentation of six strains using crystal grape must exhibited different contents of volatile compounds, with commercial strain CECA producing the highest levels of acetate esters (phenethyl acetate), ethyl esters (ethyl caprylate, ethyl hexanoate), n-caprylic acid isobutyl ester, and terpenes (linalool) whereas being ranked the last in the sensory analysis. The co-inoculation of indigenous S. japonicus with each of the six S. cerevisiae strains increased the acetate esters (mainly isoamyl acetate) by 2–3 times in crystal grape wine. The indigenous S. cerevisiae FBKL2.9128 showed the most obvious variation of volatile compounds between pure and mixed fermentation, exhibiting the significant increase of isoamyl acetate, ethyl decanoate, ethyl caprylate, ethyl hexanoate, methyl decanoate, and dodecanal when co-inoculated with S. japonicus. Sugar addition in immature crystal grape juice increased the ethanol, glycerol, and some volatile compounds such as ethyl butyrate, but decreased the volatile compounds with floral and animal odors. The aroma sensory analysis confirmed the decrease of varietal aroma in wines with sugar addition when comparing with wines made from immature crystal grape. The results of this study provide basic information on the impact of indigenous S. cerevisaie and S. japonicus, and sugar addition on typicality of crystal grape wine, which would help to improve the wine flavor made from crystal grape in southwest China.

Changes in Volatile Compounds during Grape Brandy Production from ‘Cabernet Sauvignon’ and ‘Syrah’ Grape Varieties

Grape-based brandies are one of the most popular alcoholic beverages in the world. The most popular one, Cognac, comes from the Charentes region of Southwest France, and it is mostly produced from the grape variety ‘Ugni Blanc’. However, wines destined for the elaboration of wine spirits also come from different white grape varieties; ‘Colombard’, ‘Folle Blanche’, ‘Montils’, and ‘Semillon’. In this study, the possibility of using the red grape varieties ‘Cabernet Sauvignon’ and ‘Syrah’ was investigated with an emphasis on the change of volatile compounds during the production process. During production, some specific volatile compounds such as 2-hexenal, 3-octanone, isopropyl myristate, ethyl palmitate, ethyl oleate, phenethyl acetate, 1-hexanol, and β-damascenone could be attributed to the primary aroma generated from the grape varieties. During the vinification and fermentation process, the development of ethyl hexanoate, ethyl octanoate, 3-methylbutanol, acetic acid, and octanoic acid occurred. Finally, 3-methylbutanol and predominant esters, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and ethyl laurate, were generated during the distillation and maturation process. The composition and concentration of determined predominant esters in produced brandies suggest that both brandies have volatile profiles comparable to some of the world’s most popular brandies.

Quantitative analysis of multi-components by single-marker: An effective method for the chemical characterization of wood vinegar

Wood vinegar is a complex mixture of organic compounds. QAMS is a relatively simple and cost-effective method which is used widely in recent years. In this study, quantitative analysis of multi-components by single-marker (QAMS) was applied to quantify the main volatile chemical components in wood vinegar for the first time. Using acetic acid as an internal reference compound, the relative correction factors of a further 19 chemical volatile components were obtained. 20 wood vinegar prepared from different lignocellulosic biomass, and at different pyrolysis temperatures, were analyzed by QAMS and the data compared with those obtained using an internal standard (phenethyl acetate) method. The results showed that the precision and repeatability of the QAMS method were good, and the responses obtained for each compound using GC/MS were linear over the corresponding concentration range (R2 ≥ 0.999). The average spike recoveries of 20 volatile compounds from wood vinegar ranged from 92.65% to 105.93% (RSD ＜ 7%, n = 6). There were no significant differences (P > 0.05) in the results obtained from the analysis of three batches of wood vinegar samples (RSD < 2%) using both methods. The volatile composition of samples obtained from wood vinegar prepared from the pyrolysis of different materials and at different temperatures were significantly different. The successful application of QAMS to the quantitative analysis of the composition of wood vinegar not only may provide a theoretical reference for further developments in the production, pyrolysis conditions, and modes of action for wood vinegar, but also provides ideas for the application of QAMS in other fields.

RIFM fragrance ingredient safety assessment, phenethyl acetate, CAS Registry Number 103-45-7

• Phenethyl acetate; a safety assessment based on RIFM's criteria. • A safety assessment based on 7 human health endpoints plus environmental. • All endpoints were cleared using target data, read-across, and/or TTC.

Bioproduction of Natural Phenethyl Acetate, Phenylacetic Acid, Ethyl Phenylacetate, and Phenethyl Phenylacetate from Renewable Feedstock.

Natural phenethyl acetate (PEA), phenylacetic acid (PAA), ethyl phenylacetate (Et-PA), and phenethyl phenylacetate (PE-PA) are highly desirable aroma chemicals, but with limited availability and high price. Here, green, sustainable, and efficient bioproduction of these chemicals as natural products from renewable feedstocks was developed. PEA and PAA were synthesized from l-phenylalanine (l-Phe) via novel six- and five-enzyme cascades, respectively. Whole-cell-based cascade biotransformation of 100 mm l-Phe in a two-phase system (aqueous/organic: 1 : 0.5 v/v) containing ethyl oleate or biodiesel as green solvent gave 13.6 g L-1 PEA (83.1 % conv.) and 11.6 g L-1 PAA (87.1 % conv.), respectively. Coupled fermentation and biotransformation approach produced 10.4 g L-1 PEA and 9.2 g L-1 PAA from glucose or glycerol, respectively. The biosynthesized PAA was converted to natural Et-PA and PE-PA by esterification using lipases with ethanol or 2-phenylethanol derived from sugar, affording 2.7 g L-1 Et-PA (83.1 % conv.) and 4.6 g L-1 PE-PA (96.3 % conv.), respectively.