Free Volatile Compounds Research Articles

Characterization of free and glycosidically bound volatile compounds, fatty acids, and amino acids in Vitis davidii Foex grape species native to China.

Berries of six Vitis davidii Foex (spine grape) cultivars ('Baiputao', 'Gaoshan 1', 'Gaoshan 2', 'Seputao', 'Miputao', and 'Tianputao') were harvested from a commercial vineyard in Hunan Province in China. Free and bound volatile compounds and fatty acids were analyzed by GC-MS, and amino acids were analyzed by HPLC. 'Tianputao' and 'Miputao' were characterized by relatively higher concentrations of aromatic amino acids and lower concentrations of branched-chain amino acids. The major free volatile compounds of spine grapes were hexanal, (E)-2-hexenal, 1-hexanol, (E)-2-hexenol, (E)-β-damascenone, and benzeneacetaldehyde. The major glycosidically bound volatile compounds identified were 1-hexanol, menthol, nerol, 1-butanol, 3-methyl-3-butenol, benzenemethanol, β-phenylethanol, eugenol, and guaiacol. (E)-β-damascenone, benzeneacetaldehyde, guaiacol, and eugenol had odor activity values (OAVs) > 1 in all cultivar grapes. Partial least squares discriminant analysis (PLS-DA) revealed 'Tianputao' to be distinct from the other cultivars due to its relatively higher concentrations of major terpenoids, norisoprenoids, higher alcohols, and aromatic amino acids.

Investigation of lamb fat quality attributes during deodorization

Abstract Edible lamb fat is an illustrious frying fat due to its good flavor and stability to oxidation. Fat deodorization is a vacuum–steam distillation process that is accomplished for removing the unwanted components such as free fatty acids and volatile compounds. The present work has studied the kinetics of lamb fat deodorization under different temperatures in a batch deodorization system. Variations of acid value (AV), peroxide value, p-Anisidine value, TOTOX value and total color difference were measured during the deodorization process. The Logarithmic, Wang and Singh, Hénon et al., and linear models were fitted with obtained data using nonlinear regression method. Results indicated that the Logarithmic and Henon et al. models gave the best fitness respectively with AV and p-Anisidine value, based on the statistical criteria of correlation coefficient (R 2), reduced chi-square (χ 2) and root mean square error (RMSE). Furthermore, the linear model was selected as the best model to describe the variations of TOTOX value and peroxide value during the deodorization process.

Free volatile compounds in red and purple roselle (Hibiscus sabdariffa) pomace from Indonesia

Manual headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrophotometry (GC-MS) was used for the qualitative analysis of the aromas of several tropical fruits from Indonesia i.e. two different cultivars of roselle pomace (Hibiscus sabdariffa purple and red cultivar. Pomace was used as samples as a part of valorization application of agroindustry by-product. The analytes identified included aroma compounds that can be derived from several aroma precursors. A total of 16 major volatile compounds were identified from purple roselle pomace, whereas 11 major volatile compounds were identified from red roselle pomace using HS-SPME. The major free volatile compounds were dominantly derived from fatty acid compounds. PCA analysis showed the difference in the aroma profile of two different cultivars of pomace based on the cultivar. PC1 can differentiate 86.4% between two roselle pomace cultivar whereas PC2 can differentiate 9.4% between two roselle pomace cultivar. This study also provides the map for free volatile compounds of pomace in two different roselle cultivars.

Physiochemical Properties, Volatile Compounds and Sensory Evaluation of Chili Sauce Shrimp Paste from Different Regions in Indonesia

Chili sauce shrimp paste (CSSP) is an exotic traditional sauce prepared using mainly fresh chili and shrimp paste well known as sambal terasi (Indonesia) and sambal belacan (Malaysia and Brunei). This study aims to evaluate CSSP from different regions in Indonesia on physiochemical properties, volatile compounds, and sensory evaluation. Evaluation in free amino acid (FAA) and volatile compounds were analyzed using HPLC and GC-MS. CSSP had no significant (p > 0.05) on proximate (except for moisture), salinity, pH, microbial counts and the redness index (a*/b*) compared to control. The identified volatiles can be grouped into hydrocarbon, carbonyl, sulfur, alcohol, nitrogen, fatty acid, and ester compounds. The CSSP A, B, C, D, and E (control) contained 9, 21, 12, 29, and 6 volatile compounds respectively. The total FAA ranged from 44.32 to 67.03 g/100 g, and histidine (his) was found as the most abundant in each CSSP. The rheological properties (yield stress, viscosity, and consistency) of CSSP and control values were significantly, except for CSSP B. The intensities perceived of saltiness, sweetness, and bitterness were greatly varied among CSSP. Although there is no correlation between sweetness and bitterness this is indicated by the negative correlation.

Effects of different color paper bags on aroma development of Kyoho grape berries

This study investigated the influence of red, green, blue, and white paper bags on the free volatile compound development of Kyoho grape berries from green to harvest. Seven functional groups of volatiles were identified during the development of Kyoho grape berries including esters, aldehydes, alcohols, terpenes, ketones, acids, and hydrocarbons. Esters and aldehydes were abundant in Kyoho grape berries, mainly represented by ethyl acetate, ethyl butyrate, and (E)-2-hexenal. They accumulated quickly after veraison and slightly decreased toward maturation. Red, green, blue, and white paper bags promoted the accumulation of esters and inhibited the accumulation of aldehydes, also inhibited the accumulation of alcohols, tepenes, ketones, and acids. Their effect from strong to weak was green, blue, red, and white paper bags. The expression profiles of genes in the lipoxygenase-hydroperoxide lyase (LOX-HPL) pathway were also analyzed and the results indicated that the regulation of red, green, blue, and white paper bags on aldehydes, alcohols, and esters volatile aromas was at transcriptional level. The results expanded our comprehension in grape aroma biosynthesis and berry bagging technique in table grape cultivation.

Managing wine quality using Torulaspora delbrueckii and Oenococcus oeni starters in mixed fermentations of a red Barbera wine

The use of selected starter cultures for grape must fermentation is nowadays practiced in most wine regions of the world, and as the range of available microorganisms increases this gives winemakers the possibility to increase biodiversity in guided fermentations. Nevertheless, little information is available regarding the oenological use of Saccharomyces and non-Saccharomyces yeasts in combination with lactic acid bacteria. The present study evaluates the effect of the inoculation of a non-Saccharomyces yeast, Torulaspora delbrueckii, in an alcoholic fermentation (in combination with a Saccharomyces starter), together with different modalities of malolactic fermentation management (co-inoculation, sequential inoculation and no inoculation of an Oenococcus oeni starter), on the quality of a red Barbera wine. The fermentation dynamics were verified and the final wine properties were evaluated in terms of physico-chemical composition determined by 1H-NMR, free volatile compounds measured by GC-MS and organoleptic characteristics assessed via sensory analysis. Overall, the results show that the joint employment of non-Saccharomyces yeasts did not delay alcoholic nor malolactic fermentation progress, did not interfere with the positive effect of the co-inoculation of malolactic bacteria (beneficial for both fermentation length and for the chemical, aromatic and sensory properties of wine) and enabled the production of wines with a more intense colour.

On-vine withering process of 'Moscato bianco' grapes: effect of cane-cut system on volatile composition.

Cane-cut on-vine withering is a grape dehydration technique used for dry and sweet wine production. The aim of this work was to study the influence of the cane-cut technique applied at harvest to Moscato bianco grapes during the on-vine withering process to produce dehydrated berries with a different chemical composition and a volatile profile. After 24 days of dehydration, an on-vine withering system using the cane-cut technique induced an increase in the total volatile content compared with grapes produced with a normal on-vine withering process. This increase was greater in glycosidically bound volatile compounds than in the free fraction. Bound linalool showed a significant increase of 52% when the cane-cut withering system was applied but the grapes that were normally withered appeared to be less prone to the loss of free linalool. A significant increase in the glycosylated forms of nerol and geraniol was also observed in the two on-vine withering systems on the 24th day compared with the control (fresh grapes at harvest date). A cane-cut, on-vine withering system applied at harvest induced changes in the volatile composition of Moscato bianco grapes increasing total volatile content, consisting mainly of bound compounds, by the 24th day of dehydration. The grapes dehydrated on-vine using this new system also showed significantly greater content of most of the free volatile compounds detected. © 2018 Society of Chemical Industry.

Characterization of the free and glycosidically bound aroma potential of two important tomato cultivars grown in Turkey

Free and glycosidically bound volatiles from two major tomato cultivars (Lycopersicon esculantum L. cv. Alida and Merve) of Turkey were determined. Free volatile compounds were extracted using liquid-liquid microextraction, while bound volatiles were extracted using solid phase extraction. The compounds were analyzed using GC-FID and GC-MS. Alida showed presence of, 39 free and 32 bound aroma compounds again 38 free and 31 bound aroma compounds is Merve. The odor activity values of the volatile compounds suggested that hexanal, (Z)-3-hexenal, (E,Z)-2,4-decadienal, (E,E)-2,4-decadienal and 2-phenylethanol were most significant odorants in both cultivars. Guaiacol and eugenol were flavor contributors for Merve. The norisoprenoids 5,6-epoxy-β-ionone and 3-hydroxy-β-ionone were observed in free form in tomato. Norisoprenoids, terpenoids, volatile phenols and higher alcohols were present in the glycosidic extract. Among the glycosidically bound compounds, 2-phenylethanol, guaiacol and eugenol were found to be potential contributors to overall tomato flavor upon hydrolysis.

Structurally diverse glycoconjugated volatile compounds from Oxytropis falcata Bunge

A phytochemical investigation on the whole plant of Oxytropis falcata Bunge yielded 16 glycoconjugated compounds with structurally diverse volatile aglycones but similar sugars. Of these, five were previously undescribed compounds with different volatile aglycones but same glucuronic acid (1 → 2) glucosyl moiety, including three octanol glucuronic acid (1 → 2) glucosides (1–3), one acyclic monoterpenoid glucuronic acid (1 → 2) glucoside (4), and one 4-phenyl-butan-2-ol glucuronic acid (1 → 2) glucoside (5), and 11 were biological related known glucoconjugated volatile compounds (6–16) isolated from genus Oxytropis for the first time. The structures of these compounds were determined by extensive spectroscopic analysis of MS, 1D and 2D NMR data. The absolute configurations of aglycones and sugar residues were assigned via enzymatic hydrolysis and subsequently comparison of the specific rotations. This is the first report of such structurally diverse glycoconjugated volatile compounds from O. falcata, which might be regarded as the precursor of free volatile compounds, and presents scientific evidences for better clarifying the volatile compositions of this medicinal plant and genus Oxytropis.

Influence of Maturity and Vineyard Location on Free and Bound Aroma Compounds of Grapes from the País Cultivar

Some of the volatile compounds present in grapes give wine is its unique and genuine characteristics. “Terroir” and berry maturity are considered to be the main influences on the expression of these characteristics. This work was undertaken to establish the specific characteristics that define Vitis vinifera cv. Pais, based on its aromatic profile and free and bound compounds (glycosides), and to assess the effects of location and maturity. Free and bound volatile compounds presented significant differences in the three locations studied. The total amount of free alcohols, acids and ketones depended on the location. During ripening, the amount of aroma precursors increased in all chemical groups in every location studied, and they were found mainly in the skins. With reference to free volatile compounds, it was found that cis-2-hexenol could be a good candidate to assess maturity, and that terpene content seemed to be strongly related to the vineyard location and cultivar conditions. Also, data analysis showed that the free aroma profile seemed to be influenced more by the maturity of the grapes and the bound aroma fraction more by the location.

Elusive Chemistry of Hydrogen Sulfide and Mercaptans in Wine.

This paper summarizes, discusses, and complements recent findings about the fate of H2S and methanethiol (MeSH) during wine storage. Analytical assays to determine free volatile sulfur compounds (VSCs) and brine-releasable (BR-) VSCs in combination with accelerated reductive (AR) aging and micro-oxygenation (MOX) assays allow characterizing the different categories of species able to produce H2S and MeSH and the processes of interconversion. Each wine seems to contain a specific total amount of H2S and MeSH distributed into free, metal-complexed, and oxidized forms (di and polysulfides) interconnected through reversible redox equilibria whose external expression is wine redox potential. Oxidation transforms all mercaptans likely into nonvolatile disulfides and hydrodisulfides. In anoxia, these molecules are spontaneously and quantitatively reduced back. The concomitant accumulation of major wine thiols would provoke complex dissociation and the release of free H2S and MeSH. Additionally, total amounts can increase due to the metal-catalyzed desulfhydration of cysteine and methionine.

Multi-Omics and Integrated Network Analyses Reveal New Insights into the Systems Relationships between Metabolites, Structural Genes, and Transcriptional Regulators in Developing Grape Berries (Vitis vinifera L.) Exposed to Water Deficit

Grapes are one of the major fruit crops and they are cultivated in many dry environments. This study comprehensively characterizes the metabolic response of grape berries exposed to water deficit at different developmental stages. Increases of proline, branched-chain amino acids, phenylpropanoids, anthocyanins, and free volatile organic compounds have been previously observed in grape berries exposed to water deficit. Integrating RNA-sequencing analysis of the transcriptome with large-scale analysis of central and specialized metabolites, we reveal that these increases occur via a coordinated regulation of key structural pathway genes. Water deficit-induced up-regulation of flavonoid genes is also coordinated with the down-regulation of many stilbene synthases and a consistent decrease in stilbenoid concentration. Water deficit activated both ABA-dependent and ABA-independent signal transduction pathways by modulating the expression of several transcription factors. Gene-gene and gene-metabolite network analyses showed that water deficit-responsive transcription factors such as bZIPs, AP2/ERFs, MYBs, and NACs are implicated in the regulation of stress-responsive metabolites. Enrichment of known and novel cis-regulatory elements in the promoters of several ripening-specific/water deficit-induced modules further affirms the involvement of a transcription factor cross-talk in the berry response to water deficit. Together, our integrated approaches show that water deficit-regulated gene modules are strongly linked to key fruit-quality metabolites and multiple signal transduction pathways may be critical to achieve a balance between the regulation of the stress-response and the berry ripening program. This study constitutes an invaluable resource for future discoveries and comparative studies, in grapes and other fruits, centered on reproductive tissue metabolism under abiotic stress.

Aroma profile of malbec red wines from La Mancha region: Chemical and sensory characterization

The aroma of La Mancha Malbec red wines over four consecutive vintages was characterized by chemical and sensory analysis. Solid phase extraction (SPE) and gas chromatography–mass spectrometry (GC–MS) were used to isolate and analyze free volatile compounds. Quantitative Descriptive Sensory Analysis (QDA) was carried out to characterize the sensory aroma profile. A total of 79 free volatile compounds were identified and quantified in the wines over these four vintages. Volatile aroma compounds were classified into seven aromatic series and their odour activity values were calculated in order to determine the aroma impact compounds in these wines. The aroma sensory profile of these wines was characterized by red fruit, fresh, prune, liquorice, clove, caramel, leather, tobacco and coffee aromas. This study provides a complete aroma characterization of La Mancha Malbec red wines and it is proposed that these wines can be considered as an alternative to wines from traditional grape varieties of this region.

Core Microbiota and Metabolome of Vitis vinifera L. cv. Corvina Grapes and Musts.

The composition and changes of the fungal population and of the metabolites present in grapes and in ferments of Vitis vinifera L. cv. Corvina, one of the major components of the Amarone musts, were dissected aiming at the identification of constant characteristics possibly influenced by the productive process. The fungal populations and metabolomic profiles were analyzed in three different vintages. 454-pyrosequencing on the ribosomal ITS1 region has been used to identify the fungal population present in Corvina grapes and fresh must. Samples were also subjected to metabolomics analysis measuring both free volatile compounds and glycosylated aroma precursors through an untargeted approach with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Albeit strongly dependent on the climate, both the mycobiota and metabolome of Corvina grapes and fresh musts show some characteristics recursive in different vintages. Such persistent characteristics are likely determined by the method adopted to produce Amarone or other dry wines made from partially dried grapes. In particular, the harsh conditions imposed by the prolonged withering appear to contribute to the shaping of the fungal populations. The fungal genera and metabolites present in different vintages in V. vinifera L. cv. Corvina grapes and fresh musts represent core components of the peculiar technique of production of Amarone. Their identification allows the in-depth understanding and improved control of the process of production of this economically and culturally relevant wine.

Aroma Glycosides in Grapes and Wine.

The major aroma components in grapes and wine include free volatile compounds and glycosidic nonvolatile compounds. The latter group of compounds is more than 10 times abundant of the former, and constitutes a big aroma reserve in grapes and wine. This review summarizes the research results obtained recently for the identification of aroma glycosides in grapes and wine, including grape glycoside structures, differences in aroma glycosides among grape varieties, hydrolysis mechanisms, and the factors that influence them. It also presents the analytical techniques used to identify the glycosidic aroma precursors. The operational strategies, challenges, and improvements of each step encountered in the analysis of glycosidic aroma precursors are described. This review intends to provide a convenient reference for researchers interested in the methods used for the determination of the aroma glucosides composition and the recognition of their chemical structures.

Effect of protein‐flavour binding on flavour delivery and protein functional properties: A special emphasis on plant‐based proteins

AbstractAs the loss of free volatile compounds in aqueous protein systems is known to greatly influence the quality, and therefore the consumer acceptability, of protein‐containing foods, examination of the ability of different proteins to react with volatile flavour compounds as well as the nature of the interaction are of great interest to flavour chemists. It is generally believed that the affinity of flavour to proteins is a multi‐factor function related to protein source, protein conformation and stereochemistry of the flavour compound. However, the nature of protein‐flavour interactions has not been explicit. Less focus has been put on plant‐based proteins in comparison to animal proteins. With an increase in the use of plant‐based proteins in food systems, this article provides a fundamental review of the impact protein‐flavour interactions on flavour retention and release with a special emphasis on plant protein materials. Flavour‐food matrix interactions have been examined with a focus on how they influence flavour perception. Current knowledge on methodologies involved in protein‐flavour binding studies, binding mechanisms and factors affecting the interaction have been discussed. The implication of protein‐flavour interaction on protein functionality specifically protein thermal gelation properties has also been considered. Copyright © 2016 John Wiley & Sons, Ltd.

Comparison of fortified, sfursat, and passito wines produced from fresh and dehydrated grapes of aromatic black cv. Moscato nero (Vitis vinifera L.)

Moscato nero d'Acqui is an Italian aromatic black winegrape variety characterized by a low content of anthocyanins (mostly tri-substituted), a satisfactory content of high molecular mass tannins, and a fair amount of terpenes. The grapes were subjected to a postharvest dehydration process under controlled thermohygrometric conditions (16–18°C, 55–70 RH%, 0.6m/s air speed) with the aim to produce three different special wine types (fortified, sfursat, and passito) from fresh, partially dehydrated (27°Brix), and withered (36°Brix) grapes, respectively. Chemical traits of produced grapes and wines were then evaluated through spectrophotometric, HPLC, and GC–MS methods. Increased contents of skin phenolic compounds and reduced extractable contents of seed phenolic compounds were observed as dehydration progressed. Few significant differences were found in the anthocyanin profile of grapes, although the relative abundance of coumaroylated anthocyanins was higher in dehydrated grapes. The predominant free volatile compound found in grapes was geraniol, which decreased with increasing water loss, whereas the contents of major glycosylated volatile compounds increased even above the concentration effect. The changes in the phenolic composition among wines agreed with those among grape skins. Fortified wines were chromatically unsatisfactory probably due to the low content of total anthocyanins, whereas sfursat and passito wines meet good chromatic characteristics as a result of the concentration effect during grape dehydration. Fortified and sfursat wines had free aroma profiles richer in 2-phenylethanol and citronellol, whereas passito wines were mainly composed of 2-phenylethanol and 2-phenylethyl acetate, citronellol being the predominant terpenol in all the wine types studied.

Free and Enzymatically Hydrolysed Volatile Compounds of Sweet Wines from Malvasia and Muscat Grapes (Vitis vinifera L.) Grown in Sardinia

The aroma of Muscat of Sorso-Sennori and Malvasia di Bosa wines obtained from grapes grown in Sardinia was evaluated by instrumental analysis. Gas chromatography/mass spectrometry was used to identify and quantify the content of free and bound volatile compounds. The odour activity value (OAV) was also calculated. Higher alcohols and esters were quantitatively the largest group of free volatile compounds in both wines, while terpenes were the main class of bound volatiles. A total of 52 free and 26 bound volatiles were detected. Malvasia di Bosa sweet wine had a higher content of alcohols, esters and acids in comparison to Muscat of Sorso-Sennori, which was richer in some terpenes, like nerol, geraniol and geranic acid, and also in bound volatile compounds. A total of 12 compounds were above the OAV. The main aroma-active compounds of Muscat were 3-methylbutyl acetate (banana), ethyl octanoate and hexanoate (fruity), and linalool (flowery), Malvasia wine was characterised particularly by ethyl octanoate and by 3-methylbutyl acetate.

Investigation on Phenolic and Aroma Compounds of Table Grapes from Romania

The chemical composition of Romanian table grape varieties was determined to evaluate their phenolic and aroma profiles because they are factors useful for the variety characterization and consumer acceptance. Two white table grapes (‘Aromat de Iaşi’ and ‘Timpuriu de Cluj’) and two red table grapes (‘Napoca’ and ‘Someşan’) were studied. The phenolic composition of berry skins and seeds was determined using spectrophotometric methods. The profile of anthocyanins and hydroxycinnamoyl tartaric acids (HCTs), and the content of trans-resveratrol were determined in the skins using high-performance liquid chromatographic (HPLC) methods. Free volatile compounds were quantified by gas chromatography/mass spectrometry (GC/MS). A different phenolic and aromatic composition was found in the varieties studied. Among white grapes, ‘Aromat de Iaşi’ stands out for the great number of aroma compounds, and ‘Timpuriu de Cluj’ showed high contents of polyphenols, particularly oligomeric flavanols in skins and seeds (1,171 and 1,189 mg kg-1, respectively) and total skin HCTs (181.6 mg kg-1). The red variety ‘Napoca’ had high contents of total anthocyanins (380 mg kg-1) and total skin HCTs (183.2 mg kg-1), and it is characterized by high percentages of acylated anthocyanin derivatives (28.5%) and trans-caffeoyltartaric acid forms (58.8%). ‘Someşan’ grapes showed high contents of free volatile compounds, particularly of 1-hexanol, (Z)-3-hexen-1-ol and (E)-2-hexenoic acid (167.0, 59.4 and 167.0 µg kg-1). These results may contribute to the knowledge of Romanian table grapes perspective and to a better exploitation of these varieties.

Investigation on Phenolic and Aroma Compounds of Table Grapes from Romania

The chemical composition of Romanian table grape varieties was determined to evaluate their phenolic and aroma profiles because they are factors useful for the variety characterization and consumer acceptance. Two white table grapes (‘Aromat de Iaşi’ and ‘Timpuriu de Cluj’) and two red table grapes (‘Napoca’ and ‘Someşan’) were studied. The phenolic composition of berry skins and seeds was determined using spectrophotometric methods. The profile of anthocyanins and hydroxycinnamoyl tartaric acids (HCTs), and the content of trans-resveratrol were determined in the skins using high-performance liquid chromatographic (HPLC) methods. Free volatile compounds were quantified by gas chromatography/mass spectrometry (GC/MS). A different phenolic and aromatic composition was found in the varieties studied. Among white grapes, ‘Aromat de Iaşi’ stands out for the great number of aroma compounds, and ‘Timpuriu de Cluj’ showed high contents of polyphenols, particularly oligomeric flavanols in skins and seeds (1,171 and 1,189 mg kg-1, respectively) and total skin HCTs (181.6 mg kg-1). The red variety ‘Napoca’ had high contents of total anthocyanins (380 mg kg-1) and total skin HCTs (183.2 mg kg-1), and it is characterized by high percentages of acylated anthocyanin derivatives (28.5%) and trans-caffeoyltartaric acid forms (58.8%). ‘Someşan’ grapes showed high contents of free volatile compounds, particularly of 1-hexanol, (Z)-3-hexen-1-ol and (E)-2-hexenoic acid (167.0, 59.4 and 167.0 µg kg-1). These results may contribute to the knowledge of Romanian table grapes perspective and to a better exploitation of these varieties.