Aroma potential of Albillo wines and effect of skin-contact treatment

Free and glycosidically-bound aroma compounds were analysed in Albillo grape must, skin and wines, and the effects of different skin-contact treatments on aroma composition and wine sensory characteristics were evaluated. Musts and wines contained large amounts of C₆ and benzene compounds. Must skin contact, at 18 °C for 15 and 23 h, prompted a considerable increase in free and bound varietal compounds. Therefore, this technique, and the use of glycosidases are two methods recommended as a means for enhancing wine aroma. Skin-contact treatment intensified the fresh and fruity properties that were scored positively by wine tasters.     

Aroma components of cv. Muscat of Bornova wines and influence of skin contact treatment

Aroma components of white wine made from cv. Muscat of Bornova, a natives grape variety of Vitis vinifera grown in Turkey, and the effect of skin contact treatment (15 °C, 6 and 12 h) on the aromatic profile of this wine were investigated. Aroma components were extracted with dichloromethane and then analysed by gas chromatography(GC)–flame ionisation detection and GC–mass spectrometry. A total of 72 components were identified and quantified. Skin contact treatment increased the amount of total aroma components. Wine produced with 6 h skin contact was the most preferred. From the 72 compounds identified, β-damascenone, ethyl hexanoate, ethyl butanoate, isoamyl acetate, 2-phenyl ethyl acetate, linalool, geraniol, and 2-phenyl ethanol were impact odourants of Muscat of Bornova wine on the basis of odour activity values (OAVs).     

Effect of skin contact on bound aroma and free volatiles of Listán blanco wine

Listán blanco is the major grape variety of the Canary Islands. Aroma precursors in musts and free volatiles in wines and their variations due to the skin contact process (10 °C and 0–12 h of maceration) were determined in samples of the Listán blanco grape variety. Aroma precursors of must were isolated by absorption on XAD-2 resin and the aglycone liberated by means of acid hydrolysis. Free volatiles from wines and from aroma precursors were extracted with dichloromethane and then analysed by GC-MS. The results of two consecutive vintages show that only aroma precursors of some terpenes and phenols may affect the final wine aroma. However, the majority of the free compounds of the wines did not present differences in content that could be related to the skin contact process.     

Bound aroma compounds of Gual and Listán blanco grape varieties and their influence in the elaborated wines

Listán blanco and Gual are two white grape varieties grown in Spain (Canary Islands) and Gual is also grown in Portugal (Madeira Island). Wine quality could be improved by exploiting the varietal characteristics present in grapes as aroma precursors. At the present time, the enologic potential of these varieties has not yet been studied. Aroma precursors in musts and skins, and free volatiles in wines were determined in samples of both varieties. Aroma precursors of must and skins were isolated by absorption on XAD-2 resin and the aglycone liberated by means of acid hydrolysis. Free volatiles from wines and from aroma precursors were extracted with dichloromethane and then analysed by gas chromatography-mass spectrometry (GC–MS). Among the aroma precursors analysed, only α-terpineol, linalool and linalool oxides, 4-allyl-2,6-dimethoxyphenol, 2-methoxy-4-vinylphenol, 4-hydroxybenzaldehyde, vanillin and benzyl alcohol showed contents in grapes comparable to the levels observed in wine volatile compounds.     

Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham

The aim of this work was to determine the characteristics of Istrian dry-cured ham by instrumental methods and sensory analysis. The aroma-active compounds of Istrian dry-cured ham from 2010 and 2012 were investigated by using headspace-solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics. 92 volatile aroma compounds of Istrian dry-cured ham were found. Volatile compounds belonged to several chemical groups: aldehydes (51.4; 51.3%), terpenes (16.5; 16.4%), alcohols (15.5; 13.2%), ketones (8.6; 7.4%), alkanes (3.8; 5.7%), esters (1.3; 1.6%), aromatic hydrocarbons (0.8; 3.9%) and acids (0.6; 0.9%). Principal component analysis (PCA) showed that fat content, tenderness and melting texture were positively correlated. Terpenes were strongly correlated with flavour of added spices. Sweet taste and the presence of esters were positively correlated as well as negative odour, raw meat flavour and water content.     

Characterization of key-aroma compounds of botrytized wines,influence of grape botrytization

Botrytized wines (BW) are famous for their distinctive, complex aromas. To date, only a few studies have analysed the volatile compounds involved in their typical flavours. In this paper, GC–O was applied to BW and dry white wines (DW) made from the same grape varieties to characterize the main odorants responsible for their sensory differences. Surprisingly, only two odorous zones, with grapefruit or curry nuances, were apparently specific to BW. However, GC–AEDA revealed important differences in the FD values between BW and DW, making it possible to screen potent odorants of BW, such as 3-mercaptohexan-1-ol, homofuraneol^®, furaneol^®, sotolon, methional, and phenylacetaldehyde. GC–MS quantification of homofuraneol^®, furaneol^®, norfuraneol^®, phenylacetaldehyde, and methional in 14 BW, mostly at levels above their perception thresholds, confirmed their contribution to the aroma of BW. Increased concentrations of some of these odorants in BW were shown to be associated with grape botrytization, partially through the desiccation process.     

The influence of skin contact during alcoholic fermentation on the aroma composition of Ribolla Gialla and Malvasia Istriana Vitis vinifera (L.) grape wines

Grapes from the Vitis vinifera (L.) varieties Ribolla Gialla and Malvasia Istriana were subjected to two skin contact procedures: pomace maceration and whole berry maceration during alcoholic fermentation. Wine free volatile compounds were determined using two extraction techniques coupled to GC; odour activity values were calculated and compared to control wines without skin contact. The highest concentrations of esters and relative fruity impacts were determined in the control wines for both varieties. Pomace maceration was found to be an effective procedure for the extraction of varietal aroma compounds like terpenes, but only in the Malvasia Istriana was their higher impact on floral odour determined. Pomace maceration resulted in higher total phenol and methanol content. Whole berry maceration was less efficient in terpene extraction, and its impact on general wine composition was not so radical. Control wines were chosen as preferred wines for odour and overall impression.     

Influence of deficit irrigation and kaolin particle film on grape composition and volatile compounds in Merlot grape (Vitis vinifera L.)

The effect of deficit irrigation and a kaolin-based, foliar reflectant particle film (PF) on grape composition and volatile compounds in Merlot grapes was investigated over two growing seasons in semi-arid, south-western Idaho. Vines were provided with differential amounts of water based on their estimated crop evapotranspiration (ET_c) throughout berry development, and particle film was applied to half of the vines in each irrigation main plot. Free and bound volatile compounds in grapes were analyzed using stir bar sorptive extraction–gas chromatography–mass spectrometry (SBSE–GC–MS). The concentrations of free C₆ compounds (hexanal, trans-2-hexenal, and 1-hexanol) decreased, and bound terpene alcohols (nerol and geraniol) and C₁₃-norisoprenoids (β-damascenone, 3-hydroxy-β-damascenone, 1,1,6-trimethyl-1,2-dihydronaphthalene, and 3-oxo-α-ionol) increased in berries each year in response to severity of vine water stress. Concentrations of C₁₃-norisoprenoids and bound forms of nerol and geraniol were positively correlated with their concentrations in the corresponding wines. Particle film application had minimum effect on free and bound volatile composition in the grapes, and there was no interactive effect between particle film and deficit irrigation. However, particle film application enhanced the total amount of berry anthocyanins.     

Sensory and chemical characterisation of the aroma of Prieto Picudo rosé wines: The differential role of autochthonous yeast strains on aroma profiles

This study evaluates the specific impact of isolated yeast strains on the aromatic profile of fermented musts from Prieto Picudo, an autochthonous Castilla y León (Spain) red grape variety with an increasing demand in the local marketplace. For this purpose, the aroma profiles of wines elaborated from Prieto Picudo grapes have been studied by sensory analysis, gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS), with the aim of determining the potential of each strain to generate distinctive varietal and fermentation-derived aromatic compounds. The results have shown that the yeast strain exerts a critical influence on the levels of some fermentative (linear and branched ethyl esters, fatty acids, ethyl phenylacetate) and varietal compounds (4-mercapto-4-methyl-2-pentanone, 3-mercaptohexylacetate, β-damascenone), thus inducing a deep influence on the final aroma of the wine. Combination of both sensory and chemical data arises as a major tool to monitor the different patterns of aroma release and formation from selected yeast strains during the winemaking process.     

Effects of composition,storage time,geographic origin and oak type on the accumulation of some volatile oak compounds and ethylphenols in wines

The aim of this work was to study the effect of different parameters on the accumulation of volatile oak compounds and ethylphenols in red barrel-aged wines. For this, 510 wines, from four different geographic zones and aged for various times in different oak barrel types were analysed. The results of the statistical analysis showed that the compounds were in four groups, accounting for 82.99% of the variance. The enological parameters did not present correlation with any of these four groups. The wines that remained longer in oak barrels presented, in general, higher concentrations of the studied compounds. Three of the four geographic zones were similar to each other. The oak barrel type affected the value of the ratio cis/trans, but it did not affect the accumulation of any of the volatile oak compounds or ethylphenols.     

Determination of compounds responsible for tempeh aroma

Tempeh is a fermented food, popular mainly in south-east Asia, but also among vegetarians worldwide. It is produced by fermenting soybean or other beans with Rhizopus strains and usually eaten deep-fried, steamed or roasted. The flavour of tempeh depends upon the fermentation time, beans used and the (eventual) frying process. Our goal was to identify compounds responsible for the unique aroma of fermented and fried soy tempeh. Gas chromatography–olfactometry (GC–O) with the aroma extract dilution analysis (AEDA) approach, was used to determine key odorants after 1 and 5 days of fermentation and subsequent frying. Comprehensive gas chromatography–mass spectrometry (GC × GC–ToF-MS) was used for their quantitation using stable isotope dilution analysis (SIDA) or standard addition (SA) methods. Odour activity values (OAV) were calculated for 19 out of 21 key odorants. Tempeh was fermented for 5 days and fried, and the main aroma compounds were found to be the following: 2-acetyl-1-pyrroline, (FD = 1024, OAV 1380), 2-ethyl-3,5-dimethylpyrazine (FD = 512, OAV 338), dimethyl trisulfide, (FD = 512, OAV 900), methional (FD = 512, OAV 930), 2-methylpropanal (FD = 512, OAV 311) and (E,E)-2,4-decadienal (FD = 512, OAV 455). The frying process induced the increase or appearance of the main key odorants in tempeh.     

Employment of near infrared spectroscopy to determine oak volatile compounds and ethylphenols in aged red wines

The aim of this work was to study the ability of NIR spectroscopy to determine oak volatile compounds and ethylphenols levels in aged red wines. For this purpose 510 wines aged with different storage time and in different oak barrel types were analyzed. Calibration models were developed from SBSE-GC–MS and NIR data using partial least squares (PLS) regression. In order to validate the calibration, full cross validation was employed. Results showed that the calibration statistics were very good (R² > 0.86) for all the compounds studied. In wines aged in French and in American and French oak barrels, and in “reserva” and “gran reserva” wines, the residual predictive deviation (RPD) obtained was higher than 1.5 in all the compounds and it was higher than 2 in some of the cases. In conclusion, near infrared spectroscopy can be used as a rapid tool to determine oak volatile compounds and ethylphenols in aged red wines.     

Authentication study of volatile flavour compounds composition in Slavonian traditional dry fermented salami “kulen”

Volatiles from famous Slavonian salami “kulen” were isolated by nitrogen purge and steam distillation (NPSD) and analysed, for the first time, by gas chromatography and mass spectrometry (GC and GC–MS). In all, 119 organic compounds were identified that originated from lipid oxidation, amino acid degradation, smoke treatment and added spices with different distribution among NPSD traps. NPSD method enabled comprehensive profiling with almost exclusive distribution of several major compounds in particular trap with little or no interference from abundant lipid constituents in the samples. The major identified flavour important compounds were methylphenols, methoxyphenols, organosulphur compounds (diallyl sulphide, diallyl disulphide, methylallyl disulphide, diallyl trisulphide and methional) and several derivatives of 2-cyclopenten-1-one such as ethyl cyclotene. Non-important flavour constituents such as high-molecular fatty acids, alcohols and aldehydes were also present among abundant compounds. General trends for possible discrimination of “kulen” volatiles profile among other European salami volatiles were noticed (lower amount of terpenes and higher percentages of diallyl sulphide, methoxyphenols, methylphenols and 2-cyclopenten-1-one derivatives).     

Simulation of retronasal aroma of white and red wine in a model mouth system. Investigating the influence of saliva on volatile compound concentrations

The influence of saliva on aroma release from white and red wines was studied in a model mouth system. Aroma compounds were analysed in the dynamic headspace of wines by solid phase micro extraction/gas chromatography with flame ionization detection. Volatile compounds were identified by solid phase micro extraction/gas chromatography-mass spectrometry, resulting in a total of 43 compounds in white wine and 41 in red wine. The results showed a greater influence of saliva on aroma release in white wine than red wine. In white wine treated with human saliva, esters and fusel alcohols, responsible for fruity and fusel oil odours, were reduced of 32–80%; by contrast, the concentration of 2-phenylethanol and furfural, responsible for rose and toasted almond notes, increased by 27% and by 155%, respectively. In red wine, treated with human saliva, only a few esters decrease, with a reduction of 22–51% due to protein-binding ability of polyphenols that are able to inhibit the activity of the saliva. C-13 norisoprenoids, vitispirane (eucalyptol) and TDN (kerosene), decreased both in white and red wine, showing a comparable variation while, for β-damascenone, the variation was insignificant.     

Characterization of traditional Istrian dry-cured ham by means of physical and chemical analyses and volatile compounds

The aroma-active compounds of Istrian dry-cured ham were investigated by using headspace-solid phase microextraction and gas chromatography-mass spectrometry (GC-MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics: moisture, protein, fat, ash and NaCl content, a(w) value; colour: L*, a*, b* and oxidation of fat: TBARS test. About 50 volatile compounds were identified and quantified which belonged to several classes of chemical: 5 alcohols, 8 aldehydes, 7 alkanes, 1 ketone, 2 esters, 9 monoterpenes and 15 sesquiterpenes. Except volatile compounds derived from lipolysis and proteolysis the most abundant constituents were terpenes (62.97; 41.43%) that originate from spices added in the salting phase of the production process.     

Odour-active compounds of an Eisenia foetida protein powder. Identification and effect of delipidation on the odour profile

The odour-active compounds (OAC) of an Eisenia foetida (Ef) protein powder were determined using a detection frequency gas chromatography–olfactometry method. They were isolated by a Solvent-Assisted Flavour Evaporation Extraction (SAFE) method. Sixty-eight compounds were designated as OAC, 41 of which were identified. Fifty-one percent of the identified compounds came from lipid oxidation. A Soxhlet delipidation method, with hexane, and an ultrasound extraction method, with a chloroform/methanol mixture, were used in order to dearomatize the Ef protein powder. The effect of delipidation on the OAC was studied. The Soxhlet and the ultrasound methods eliminated 70.5% and 97.7% of the OAC, respectively. The Ef protein powder was characterised by animal, chemical, earthy, floral, fruity and vegetable attributes. Soxhlet extraction reduced the vegetable and the herbaceous attributes, whereas ultrasound extraction reduced the chemical, earthy, floral, fruity and Maillard attributes.     

Examination of freshness degradation of sourdough bread made with kefir through monitoring the aroma volatile composition during storage

The aroma volatile compositions of sourdough breads containing kefir grains were monitored by SPME GC–MS analysis during a 5-day storage. Breads were made with (A) 20% w/w and (B) 10% w/w (on flour basis) kefir sourdough, and were compared with breads made with 20% w/w commercial sourdough (C) and sourdough prepared in the laboratory (D) without addition of starter culture. A dramatic decrease of volatiles was observed during storage for all samples, but the kefir sourdough breads (A and B) exhibited more complex profiles of volatiles with lower loss rates during storage. Differences in the percentages of esters on total volatiles were also observed (6.2%, 5.0%, 2.8% and 2% in the case of breads A, B, C, and D, respectively). The customer oriented sensory evaluation revealed significant differences among the tested samples, with best results scored in the case of bread A in all days of storage, agreeing with the analytical data.     

Analysis of volatile compounds in traditional smoke-cured bacon(CSCB) with different fiber coatings using SPME

The volatile compounds of Chinese traditional smoke-cured bacon (CSCB) were studied using SPMS-GC/MS. There were 48 volatile compounds identified and quantified, which belonged to several classes of chemical: 1 alkane, 16 aldehydes, 5 ketones, 9 alcohols, 4 thioethers and thiols, 3 furans and 10 phenols compounds. All the volatile compounds except for alkane was responsible for CSCB characteristic flavor. The major volatile compounds of CSCB came from smoking, oxidation and Maillard reaction, etc. Many volatile compounds were not reported in previous paper isolated by steam distillation method or nitrogen purge-and-steam distillation method on CSCB. It should be because of different method of isolating volatile substances from CSCB. Among the fibers tested, CAR/PDMS (carboxen/polydimethylsiloxane) fiber coating showed the highest area counts for most volatile compounds. CAR/PDMS coating extracted better those compounds whose linear retention indices (LRI) was lower than 926 (on average) and DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) those with higher LRI.     

Odour active aroma compounds of sea fig (Microcosmus sulcatus)

Sea fig is an original shellfish appreciated for its powerful “marine, iodized” flavour. Different methods of analysis by gas chromatography, coupled with olfactometry (GC–O), were studied and compared. Subsequently, odour-active aroma compounds of sea fig extract were analyzed by OSME and CHARM analysis. Twenty-nine olfactive areas were observed by OSME, and 18 by CHARM analysis. Volatile compounds of the extract were analyzed by mass spectrometry and specific detectors associated with the GC. Twenty molecules, responsible for these odours were elucidated. Among them, 12 were directly identified by GC–MS, and the remaining 8 only by GC–O and standard sample injection. Moreover, 10 volatile sulfur-containing compounds were revealed as the major olfactive contributors. The two principal character-impact compounds possessed “marine, fresh” and “fishy, crustaceous” odours. The first could not be identified; however, trimethylamine was attributed to the other, and defined as a key compound of sea fig aroma.     

The role of volatile compounds on aroma and flavour perception in coloured raw carrot genotypes

Quantitative analyses of volatile compounds isolated from raw carrots were combined with sensory analysis in order to identify the role of these compounds on aroma and flavour perception in coloured carrots. A sensory map of carrots with different colours was developed, the content of the isolated volatiles was determined and the role of these compounds for harsh flavour perception in raw coloured carrots was evaluated using multivariate data analysis. The sensory map showed that the coloured carrots formed distinct groups within the sensory profile. The orange genotypes were characterised by having significantly higher intensities in carrot flavour and aroma, while the reverse was true for the yellow genotypes. The purple genotype was characterised by having significantly higher intensity in sickenly sweet flavour and nutty flavour, and the red genotype was characterised by having significantly higher intensities in green aroma and flavour, bitterness and burning aftertaste. From the multivariate data analysis it was concluded that the isolated terpenes do correlate to the harsh flavour attributes.