Semi-quantitative analysis of volatile compounds in the headspace of model wines

2.3.1.2.1. Riesling

The model wines, produced by supplementation and subsequent fermentation, of grape berry tissues or whole berries, were analysed for their volatile compound composition. The target list of compounds was chosen to be those volatiles that were influenced by the amount of grape material in model must in experiments by Keyzers et al. (Keyzers and Boss, 2010).

This list contained 101 Riesling compounds, and 91 of these were detected in the chromatographs produced in this experiment. It was not possible to resolve

2-methylbutanol and 3-2-methylbutanol with the chromatographic method used, so they were treated as a single analyte. There were 10 compounds that were not detected in this experiment, and these are listed in Table 8. The concentrations of the 91 volatile

compounds that were detected in the headspace of the wines produced from whole berries and grape tissues were tested using ANOVA to identify those that were significantly different amongst the wines. The statistical analysis showed that 13 of these wine volatile compounds did not differ between fermentations (Table 9), while 78 compounds were significantly different due to the source of the material used in the fermentations (Table 10).

Table 8: Grape influenced compounds that were not detected in EW Riesling wines

Target compounds not detected

aliphatics esters

(E)-2-nonenal 3-(methylthio)propyl acetate 2-pentadecanone 3-methylbutyl decanoate 2-undecanol ethyl (Z)-9-octadecenoate

ethyl heptanoate ethyl octadecanoate octyl acetate pentyl acetate

Table 9: Grape influenced compounds that were not significantly different between EW Riesling γ-nonalactone geranyl ethyl ether ethyl 3-methylbutanoate geranyl acetate ethyl pentadecanoate

nor-isoprenoids carboxylic acids vitispirane 2

octanoic acid

nonanoic acid aromatics decanoic acid 2-phenylethanol dodecanoic acid

2.3.1.2.1.1. Most compounds did not differ in concentration between homogenised and crushed ‘whole berry’ wines.

There were two ‘whole berry’ fermentation treatments, homogenised and crushed, and the majority, 61 out of 91, of compounds did not significantly differ in

concentration between these two treatments. Of the 17 compounds that did differ, six were found in higher concentrations in crushed ‘whole berry’ wines than in

homogenised ‘whole berry’ wines; Riesling acetal, acetic acid, 3-ethoxypropanol, butyl acetate, ethyl acetate and 2-methylpropyl acetate (Table 10). There were 11 compounds that were present in higher concentrations in homogenised ‘whole berry’ wines than in crushed ‘whole berry’ wines; β citronellol, 3-methylbutyl octanoate, diethyl succinate, ethyl undecanoate , ethyl dodecanoate, ethyl tetradecanoate, ethyl hexadecanoate, ethyl phenylacetate, phenylethyl acetate, (Z)-3-hexenol, and

2-methylbutanol/3-methylbutanol.

2.3.1.2.1.2. Differences in tissue influenced volatile compounds

There were 20 compounds that were more concentrated in flesh-derived wines than in wines made from seeds. A total of 36 compounds were not significantly different

when comparing flesh-derived wines to seed-derived wines. Seed-derived wines had higher concentrations of 35 compounds compared to flesh-derived wines, mostly

comprising ethyl esters of fatty acids, amyl esters, methyl ketones and esters of aromatic alcohols.

There were 33 compounds that were more concentrated in skin-derived wines than in seed-derived wines, which tended to be monoterpenoids, C6 alcohols,

norisoprenoids, methionine catabolites. A total of 33 compounds did not significantly differ when comparing skin- and seed-derived wines. Seed-derived wines had greater concentrations of 25 compounds than wines made from skins, with these compounds representing ethyl esters of fatty acids, amyl esters, methyl ketones and esters of aromatic alcohols.

There were three compounds that were more concentrated in wines made from flesh than in wines made from skins, specifically; acetic acid, α-farnesene and an α-farnesene isomer. A total of 51 compounds did not significantly differ when comparing flesh-derived wines to wines made from skins. There were 37 compounds that were more highly concentrated in wines made from skins than in wines made from flesh, which tended to be monoterpenoids and C6 alcohols.

Table 10: Grape influenced compounds that were significantly different between EW Riesling wines. Geometric means (n=3) are of the peak area of the quantifier ion for that compound divided by the peak area of the quantifier ion for the relevant internal standard. Statistical similarity between means is indicated by values with the same letter in superscript (Tukey post-hoc).

geometric means (n = 3) Whole

berry Whole berry

Compound Flesh Skin Seed (crushed) (homogenised

) aliphatics

2-heptanone 0.0110^D 0.0132^CD 0.0446^A 0.0257^B 0.0175^BC

2-nonanone 0.0427^C 0.0726^B 0.190^A 0.0756^B 0.100^B

2-undecanone 0.00828^B 0.0225^A 0.0261^A 0.0178^A 0.0228^A

geometric means (n = 3) Whole

berry Whole berry

Compound Flesh Skin Seed (crushed) (homogenised

) 2-tridecanone 0.0204^C 0.0632^A 0.0445^AB 0.0479^AB 0.0376^B

butanol 0.00450^B 0.00597^A

B 0.00730^A 0.00496^AB 0.00484^B 2-nonanol 0.0323^AB 0.0637^A 0.0180^B 0.0394^AB 0.0748^A octanol 0.0138^D 0.0534^A 0.0408^AB 0.0169^CD 0.0275^BC

nonanol 0.0146^D 0.259^A 0.0149^CD 0.0260^BC 0.0402^B

decanol 0.00900^B 0.0246^A 0.00590^B 0.00803^B 0.0104^B dodecanol 0.00861^A 0.00957^A 0.000346

B 0.0152^A 0.00889^A

rac-2,3-butanediol 0.220^C 0.313^BC 1.18^A 0.557^B 0.453^B meso-2,3-butanediol 0.0669^C 0.114^BC 0.276^A 0.166^AB 0.127^BC 2-methylpropanol 0.317^A 0.295^A 0.117^B 0.331^A 0.263^A

2-methylbutanol/3-methylbutanol 14.6^BC 21.4^A 15.7^B 11.8^C 16.2^AB

3-ethoxypropanol 0.0400^AB 0.0347^B 0.0394^AB 0.0543^A 0.0312^B (E)-2-octenal 0.00255^B 0.00300^B 0.0211^A 0.00208^B 0.0107^AB

3-(methylthio)propanol 0.0690^A 0.0956^A 0.000344

B 0.0261^A 0.0464^A

hexanol 0.773^C 4.06^A 0.925^C 1.72^B 1.95^B

(E)-3-hexenol 0.00706^C 0.0345^A 0.00484^C 0.00796^C 0.0156^B (Z)-3-hexenol 0.000936^C 0.0297^A 0.00493^B 0.00490^B 0.00716^B hexanal 0.00223^B 0.00363^B 0.00899^A 0.00281^B 0.00416^AB

esters

hexyl acetate 0.00501^C 0.0217^AB 0.0383^A 0.0120^B 0.0127^B (Z)-3-hexenyl acetate 0.00273^C 0.0120^A 0.00947^AB 0.00327^C 0.00500^BC ethyl (E)-3-hexenoate 0.00182^C 0.0127^A 0.00432^B 0.00297^BC 0.00288^BC ethyl

3-(methylthio)propanoat e

0.00635^A 0.00664^A ND^C 0.00174^B 0.00328^B

ethyl acetate 1.64^AB 0.953^B 2.60^A 2.85^A 1.29^B

ethyl butanoate 0.153^C 0.179^C 0.542^A 0.350^AB 0.206^BC ethyl 2-butenoate 0.00511^C 0.00995^B 0.0244^A 0.00871^BC 0.00955^B

ethyl hexanoate 2.28^B 2.96^B 17.1^A 3.69^B 3.23^B

ethyl octanoate 3.11^B 4.08^B 29.2^A 4.02^B 4.95^B

ethyl nonanoate 0.00281^B 0.00224^B 0.0146^A 0.00311^B 0.00277^B

ethyl decanoate 3.51^B 3.94^B 11.8^A 3.14^B 4.19^B

ethyl 9-decenoate 0.309^A 0.227^AB 0.108^B 0.310^A 0.349^A ethyl undecanoate 0.00179^AB 0.00178^A

B 0.00358^A 0.00152^B 0.00379^A ethyl dodecanoate 0.212^C 0.357^C 1.62^A 0.0685^D 0.660^B ethyl tetradecanoate 0.00500^B 0.00490^B 0.036^A 0.00147^C 0.0139^AB ethyl

3-hydroxytridecanoate 0.0109^AB 0.0161^A 0.00378^B 0.0140^AB 0.0135^AB ethyl hexadecanoate 0.00361^B 0.00316^B 0.00904^AB 0.00399^B 0.0177^A

methyl hexanoate 0.00125^C 0.00266^A

B 0.00436^A 0.00177^BC 0.00120^C

geometric means (n = 3) Whole

berry Whole berry

Compound Flesh Skin Seed (crushed) (homogenised

)

methyl decanoate 0.00468^B 0.00780^A 0.00564^AB 0.00430^B 0.00519^AB 3-methylbutyl acetate 1.3^B 1.48^B 5.59^A 1.75^B 1.61^B 3-methylbutyl

hexanoate 0.0121^C 0.0206^B 0.0882^A 0.0167^BC 0.0216^B 3-methylbutyl

octanoate 0.00589^C 0.0135^B 0.0478^A 0.00373^C 0.0141^B ethyl phenylacetate 0.0184^B 0.0407^A 0.0323^A 0.0107^C 0.0185^B phenylethyl acetate 0.536^CD 1.47^B 5.27^A 0.457^D 0.786^C 2-phenylethyl

butanoate 0.00153^D 0.00635^B 0.0195^A 0.00176^CD 0.0028^C

butyl acetate 0.0104^BC 0.00890^B

C 0.0202^A 0.0124^B 0.00729^C

heptyl acetate 0.00661^B 0.00465^B 0.0153^A 0.00573^B 0.00413^B 2-methylpropyl

acetate 0.0356^B 0.0210^B 0.0346^B 0.0660^A 0.0263^B

ethyl 2-furoate 0.00840^B 0.0128^A 0.00267^C 0.00890^AB 0.00689^B diethyl succinate 0.118^BC 0.225^A 0.160^AB 0.105^C 0.160^AB

carboxylic acids

acetic acid 1.58^AB 1.15^C 1.49^A 1.50^A 1.31^B

hexanoic acid 0.544^C 0.845^B 1.36^A 0.712^B 0.773^B

terpenoids

myrcene ND^C 0.00186^A ND^C 0.000643^B 0.000333^B

limonene 0.00141^AB 0.00400^A 0.00282^AB 0.00178^AB 0.00113^B

ocimene 0.000493^A

B 0.00203^A ND^B 0.000783^A 0.00145^A

terpinolene 0.00127^A 0.00304^A ND^B 0.00176^A 0.00220^A (p)-cymene 0.00738^B 0.0709^A 0.0112^B 0.0220^AB 0.0179^B linalyl ethyl ether 0.00227^B 0.00836^A 0.00107^C 0.00178^BC 0.00172^BC α-terpinyl ethyl ether 0.00247^B 0.00553^A 0.00123^B 0.00294^AB 0.00232^AB nerol oxide 0.0160^A 0.0165^A 0.00384^B 0.0150^A 0.0118^A

linalool 0.0148^B 0.105^A 0.0102^B 0.0189^B 0.0260^B

hotrienol 0.0285^B 0.0733^A 0.00493^C 0.0168^B 0.0205^B α-terpineol 0.00302^BC 0.0275^A 0.00173^C 0.00444^B 0.00457^B β-citronellol 0.0172^BC 0.0686^A 0.00469^D 0.0167^C 0.0303^B nerol 0.000699^C 0.00545^A 0.000292^D 0.000789^BC 0.00149^B

α-farnesene 0.000103^A ND^B ND^B 0.0000613^A

B ND^B

α-farnesene isomer 0.00303^A 0.00107^B

C 0.000469^C 0.00212^AB 0.00112^BC β-farnesene 0.0104^A 0.00606^A

B 0.00205^C 0.00769^AB 0.00468^BC

nerolidol 0.0134^A 0.00734^A

B 0.000664^D 0.00526^BC 0.00300^C

nor-isoprenoids

vitispirane 1 0.00181^AB 0.00892^A 0.000213^B 0.00251^AB 0.002225^AB riesling acetal 0.00197^C 0.0117^A 0.000797^D 0.00383^B 0.00214^C

geometric means (n = 3) Whole

berry Whole berry

Compound Flesh Skin Seed (crushed) (homogenised

)

1,1,6-trimethyl-1,2-dihydronaphthalene 0.00280^A 0.00233^A ND^B 0.00224^A 0.00163^A β-damascenone 0.0667^A 0.0927^A 0.00600^B 0.0626^A 0.0520^A

aromatics

benzaldehyde 0.0150^B 0.0277^B 0.0838^A 0.0236^B 0.0219^B benzyl alcohol 0.00148^C 0.0164^A 0.0106^A 0.00328^B 0.00382^B (p)-vinylguaiacol 0.00364^A 0.00197^A 0.000129^B 0.00054^AB 0.00117^AB

2.3.1.2.1.3. Principal component analysis (PCA) of the volatile profiles obtained from the Riesling wines made from berry tissues

To better visualise relationships between the berry tissues used in the fermentations and the volatile compounds found in the headspace of the wines, PCA was carried out on compounds that were found to be significantly different amongst the wines by the ANOVA. The first two principal components were able to explain a combined 86.84 % of the total variance, with PC-1 explaining 52.40 %, and PC-2 explaining 34.45 %. The next two principal components explained 7.38 % (PC-3) and 5.78 % (PC-4) of the total variance respectively, and were therefore not considered to be of great importance to understanding the relationship between the samples. A projection of volatile

components onto the factor space of the first two principal components is shown in Figure 7. The abbreviations used in the PCA figures in this chapter are tabulated with their compound names in Table 11.

Wines made with seed tissue had high positive PC-1 scores and are located on the extreme right-hand side of the biplot (Figure 7). Compounds with high positive PC-1 loadings were methyl ketones (2-heptanone and 2-nonanone), ethyl esters (ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, ethyl

9-acetate, isoamyl esters (methylbutyl 9-acetate, methylbutyl hexanoate and 3-methylbutyl octanoate), hexanal, butanediols (rac-2,3-butanediol and meso-2,3-butanediol), other esters (butyl acetate and heptyl acetate), and benzaldehyde.

Wines made with skin tissue had high negative PC-1 scores and high positive PC-2 scores. As such, they are found in the upper left had side of the bi-plot (Figure 7).

Compounds with high negative PC-1 loadings were some nor-isoprenoids (TDN, β-damascenone), nerol oxide, ethyl 3-hydroxytridecanoate, 2-methylpropanol, and ethyl 2-furoate. Compounds with high positive PC-2 loadings (p-value<0.05) were (Z)-3-hexenol, octanol, amyl alcohol (2- and 3-methylbutanol), limonene, ethyl phenylacetate, methyl decanoate, diethyl succinate, and ethyl (E)-3-hexenoate. As a group, the

monoterpenes stand out in this analysis as they have both high negative PC-1 and positive PC-2 loadings and are most associated with the wines produced from skins.

The same is true for the C6 alcohols; hexanol, (E)-3-hexenol and (Z)-3-hexenol.

Similarly, skin wines associated with the nor-isoprenoids; vitispirane 1 and Riesling acetal, and additionally associated with nonanol and decanol (Figure 7).

Table 11: Abbreviations used in the PCA figures for compound names in this chapter

Abbreviation Compound name

"(E)2heptal" (E)-2-heptenal

"(E)-3-hexenol" (E)-3-hexenol

"(E)-octal" (E)-2-octenal

"(p)-cym" (p)-cymene

"(p)vgcol" (p)-vinylguaiacol

"(Z)3hexen ac" (Z)-3-hexenyl acetate

"(Z)-3-hexenol" (Z)-3-hexenol

"1octen3ol" 1-octen-3-ol

"2/3-mbol" 2-methylbutanol/3-methylbutanol

"2ethex ac" 2-ethylhexyl acetate

"2-heptol" 2-heptanol

"2-hptone" 2-heptanone

"2-mp ac" 2-methylpropyl acetate

"2mp acid" 2-methylpropanoic acid

"2-mp oct" 2-methylpropyl octanoate

"2mpol" 2-methylpropanol

"2-nnol" 2-nonanol

"2-nnone" 2-nonanone

"2-trdcone" 2-tridecanone

"2-udcone" 2-undecanone

"3(mt)pol" 3-(methylthio)propanol

"3-etoxprop" 3-ethoxypropanol

"3mb ac" 3-methylbutyl acetate

"3mb ddec" or "3mb dodec" 3-methylbutyl dodecanoate

"3mb dec" 3-methylbutyl decanoate

"3mb hex" 3-methylbutyl hexanoate

"3mb oct" 3-methylbutyl octanoate

"3-octone" 3-octanone

"3OH2butone" 3-hydroxy-2-butanone

"ac acid" acetic acid

"a-farne iso" α-farnesene isomer

"a-farne" α-farnesene

"a-terp et eth" α-terpinyl ethyl ether

"a-terpineol" or "a-terpol" α-terpineol

"a-terpne" α-terpinene

"B-citrnlol" β-citronellol

"B-dmscone" β-damascenone

"B-farne" β-farnesene

"but ac" butyl acetate

"but acid" butanoic acid

"butol" butanol

"bzalde" benzaldehyde

"bzol" benzyl alcohol

Abbreviation Compound name

"bzphene" benzophenone

"cadalene" cadalene

"ddcol" dodecanol

"dec acid" decanoic acid

"decol" decanol

"diet succ" diethyl succinate

"et (E)3hexet" ethyl (E)-3-hexenoate

"et 2bute" ethyl 2-butenoate

"et 2-fur" ethyl 2-furoate

"et 2mp" ethyl 2-methylpropanoate

"et 3(mt)prop" ethyl 3-(methylthio)propanoate

"et 3mb" ethyl 3-methylbutanoate

"et 3OHtrdec" ethyl 3-hydroxytridecanoate

"et 9dece" ethyl 9-decenoate

"et 9hxdc" ethyl 9-hexadecenoate

"et ac" ethyl acetate

"et but" ethyl butanoate

"et ddec" or "et dodec" ethyl dodecanoate

"et dec" ethyl decanoate

"et hex" ethyl hexanoate

"et hexdec" ethyl hexadecanoate

"et hpt" ethyl heptanoate

"et non" ethyl nonanoate

"et oct" ethyl octanoate

"et pentdec" ethyl pentadecanoate

"et phenac" ethyl phenylacetate

"et prop" ethyl propanoate

"et tetdec" ethyl tetradecanoate

"et udec" ethyl undecanoate

"ger ac" geranyl acetate

"ger et eth" geranyl ethyl ether

"geraniol" geraniol

"hept ac" or "hpt ac" heptyl acetate

"heptol" heptanol

"hex ac" hexyl acetate

"hex acid" hexanoic acid

"hexal" hexanal

"hexol" hexanol

"hotrienol" hotrienol

"limonene" limonene

"lin et eth" linalyl ethyl ether

"linalool" linalool

"m-2,3-bdiol" meso-2,3-butanediol

"me dec" methyl decanoate

"me hex" methyl hexanoate

Abbreviation Compound name

"me oct" methyl octanoate

"myrcene" myrcene

"ner ox" nerol oxide

"ner prop" neryl propanoate

"nerol" nerol

"nerolidol" nerolidol

"non acid" nonanoic acid

"nonol" nonanol

"ocimene" ocimene

"oct acid" octanoic acid

"octol" octanol

"pent ac" pentyl acetate

"phenet ac" phenylethyl acetate

"phenet but" 2-phenylethyl butanoate

"phenet oct" 2-phenylethyl octanoate

"phenetol" 2-phenylethanol

"phenol" phenol

"prop ac" propyl acetate

"prop hex" propyl hexanoate

"propol" propanol

"r-2,3-bdiol" rac-2,3-butanediol

"Ries acet" riesling acetal

"TDN" 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN)

"terpolene" terpinolene

"vitspir 1" vitispirane 1

"y-nnlact" γ-nonalactone

Figure 7: PCA bi-plot EW Riesling wines and grape influenced aroma compounds. Abbreviations used in this figure are tabulated with their compound names in Table 11

2.3.1.2.2. Cabernet Sauvignon

The volatile compound composition of the Cabernet Sauvignon model wines was analysed using HS-SPME-GCMS. A target list of 115 compounds that changed with increasing percentage of Cabernet Sauvignon grape juice in fermentations of model must, as described in by Keyzers and co-workers (Keyzers and Boss, 2010), was used to focus on volatile compounds influenced by grape composition. Of the 115 compounds, 89 were detected in this experiment, although 2-methylbutanol and 3-methylbutanol could not be chromatographically resolved, so were analysed as a single analyte. The 26

compounds that were not detected are listed in Table 12. A total of 24 compounds (including both 2-methylbutanol and 3-methylbutanol) showed no significant difference in concentration between treatments (Table 13), whereas 66 compounds significantly differed in abundance between the treatments (Table 14).

Table 12: Grape influenced aroma compounds that were not detected in EW Cabernet Sauvignon wines.

Target compounds not detected

aliphatics carboxylic acids

2-pentadecanone 2-ethylhexanoic acid

2-undecanol 9-decenoic acid

pentanol dodecanoic acid

esters terpenoids

2-heptyl acetate 2,3-dihydrofarnesol 2-methylpentyl acetate farnesol

3-(methylthio)propyl acetate farnesyl acetate 9-decenyl acetate β-citronellyl acetate

benzyl acetate

decyl acetate aromatics

ethyl (E)-2-hexenoate (p)-vinylguaiacol ethyl (Z)-9-octadecenoate

ethyl 3-(methylthio)propanoate other

ethyl octadecanoate 2-methyldihydro-3(2H)-thiophenone ethyl (E)-3-hexenoate

ethyl undecanoate

octyl acetate

propyl octanoate

Table 13: Grape influenced aroma compounds that were not significantly different between EW Cabernet Sauvignon wines.

class

compound

aliphatics carboxylic acids

propanol heptanoic acid

2-heptanone decanoic acid

2-methylbutanol/3-methylbutanol

2-heptanol terpenoids

rac-2,3-butanediol linalool

meso-2,3-butanediol

dodecanol aromatics

benzophenone

esters benzothiazole

3-methylbutyl butanoate (Z)-3-hexenyl acetate

propyl hexanoate

class

compound

heptyl acetate

ethyl nonanoate

methyl decanoate

methyl dodecanoate

ethyl 4-hydroxybutanoate

2.3.1.2.2.1. Most compounds did not significantly differ in concentration between homogenised and crushed ‘whole berry’ wines.

There were 16 compounds whose concentrations significantly differed between homogenised and crushed ‘whole berry’ wines, and 73 which were not significantly different in concentration between homogenised and crushed ‘whole berry’ wines.

There were four compounds that were higher in concentration in crushed ‘whole berry’

wines than in homogenised ‘whole berry’ wines; benzyl alcohol, nerolidol, β-citronellol and β-farnesene. Homogenised ‘whole berry’ wines had higher abundance of 12

compounds than crushed ‘whole berry’ wines; phenylethanol, butanoic acid, 2-phenylethyl octanoate, ethyl 9-hexdecenoate, ethyl dodecanoate, ethyl tetradecanoate, ethyl hexadecanoate, 3-methylbutyl octanoate, 3-methybutyl decanoate, 3-methylbutyl dodecanoate, hexanol and heptanol.

2.3.1.2.2.2. Differences in tissue influenced volatile compounds

When comparing the headspace volatile profiles from the wines produced using either the flesh or seeds of Cabernet Sauvignon grapes (Table 13 and Table 14), there were similar numbers of compounds that were either in higher concentration in the seed-derived wines (30), the flesh-derived wines (27), or not significantly different between the two (32). Compounds that were generally higher concentrated in wines made from flesh than from seeds were the methionine catabolites, hexanol, hexyl acetate, terpenoids and norisoprenoids. Seed derived wines generally contained significantly higher concentrations of ethyl esters of fatty acids, amyl esters, aromatic esters, and fatty acids than flesh derived wines.

There were 26 compounds that were more concentrated in skin-derived wines than in seed-derived wines, and 40 compounds that did not significantly differ when

comparing skin- and seed-derived wines. Terpenoids and norisoprenoids as well C6 alcohols were notably more concentrated in skin-derived wines than in seed-derived wines. Seed-derived wines had greater concentrations of 23 compounds than wines made from skins, primarily the ethyl esters of fatty acids, amyl esters, aromatic esters, and fatty acids.

Only three compounds were more concentrated in wines made from flesh than in wines made from skins, specifically; phenylethyl acetate, ethyl hexadecanoate and propyl acetate. A total of 68 compounds did not significantly differ when comparing flesh-derived wines to wines made from skins. There were 12 compounds that were more highly concentrated in wines made from skins than in wines made from flesh, chiefly monoterpenoids and C6 alcohols.

Table 14: Grape influenced aroma compounds that were significantly different between EW Cabernet Sauvignon wines. The geometric means reported are the peak area of the quantifier ion for that compound divided by the peak area of the quantifier ion for the relevant internal standard.

Statistical similarity between means is indicated by values with the same letter in superscript (Tukey post-hoc).

2-nonanone 0.251^A 0.242^AB 0.153^B 0.157^AB 0.173^AB

2-undecanone 0.0333^A 0.0319^A 0.0296^AB 0.0178^B 0.0271^AB

butanol 0.0585^B 0.123^A 0.0583^B 0.0391^BC 0.0353^C

heptanol 0.0584^B 0.120^A 0.102^A 0.0427^C 0.0623^B

2-nonanol 0.0606^AB 0.0702^A 0.0353^C 0.0639^AB 0.0545^B

octanol 0.0373^B 0.0589^A 0.044^B 0.0382^B 0.0431^B

decanol 0.0144^A 0.0168^A 0.00493^B 0.0151^A 0.0148^A

3-hydroxy-2-butanone 0.0266^A 0.0194^AB 0.00100^B 0.0114^AB 0.00393^AB

geometric means (n=3)

2-methylpropanol 0.168^AB 0.207^A 0.0817^B 0.164^AB 0.107^AB 1-octen-3-ol 0.0398^B 0.0404^B 0.214^A 0.0288^B 0.0274^B 3-octanone 0.0101^A 0.00897^A 0.00278^B 0.0109^A 0.0112^A 3-ethoxypropanol 0.0544^A 0.0412^AB 0.0742^A 0.0401^AB 0.0257^B

3-(methylthio)propano

l 0.159^A 0.168^A 0.0023^C 0.0631^B 0.0747^B

hexanol 1.11^C 2.87^A 0.473^D 0.988^C 1.41^B

(E)-3-hexenol 0.012^AB 0.0367^A 0.00254^B 0.0096^AB 0.0039^AB (Z)-3-hexenol 0.00138^B 0.0162^A 0.00429^AB 0.00318^AB 0.00183^B hexanal 0.00235^BC 0.00385^AB 0.00446^A 0.0016^C 0.00258^BC

esters

hexyl acetate 0.0108^A 0.0112^A 0.00168^B 0.00733^A 0.0104^A

ethyl acetate 1.35^B 1.27^B 2.76^A 1.45^B 1.31^B

ethyl propanoate 0.0359^A 0.0288^AB 0.0186^B 0.028^AB 0.0243^AB ethyl butanoate 0.298^B 0.330^B 0.669^A 0.402^AB 0.349^B ethyl 2-butenoate 0.0106^C 0.0156^B 0.0258^A 0.0207^A 0.021^A

ethyl hexanoate 3.94^B 4.35^B 10.2^A 4.67^B 4.41^B

ethyl octanoate 4.12^B 4.40^B 13.0^A 4.99^B 4.97^B

ethyl decanoate 1.23^BC 0.874^C 6.69^A 1.09^BC 1.39^B ethyl 9-decenoate 0.126^A 0.0933^AB 0.0792^B 0.0994^AB 0.115^A ethyl dodecanoate 0.160^C 0.144^C 1.60^A 0.11^C 0.445^B ethyl

tetradecanoate 0.00921^B 0.0071^B 0.0783^A 0.006^B 0.0286^A ethyl

pentadecanoate 0.00274^A 0.00206^AB 0.00108^B 0.00293^A 0.00345^A ethyl

hexadecanoate 0.0128^B 0.00725^C 0.0359^A 0.00392^D 0.0374^A ethyl

9-hexadecenoate 0.00195^AB

0.000749^B

C 0.00228^AB 0.000346^C 0.0047^A 3-methylbutyl

acetate 2.32^B 2.33^B 8.64^A 2.83^B 2.41^B

3-methylbutyl

octanoate 0.00372^CD 0.00426^C 0.0382^A 0.00266^D 0.0069^B 3-methylbutyl

decanoate 0.0358^B 0.0345^B 0.0916^A 0.0298^B 0.0928^A 3-methylbutyl

dodecanoate 0.00336^B 0.00267^B 0.00502^AB 0.00176^B 0.0154^A propyl acetate 0.0215^B 0.011^C 0.0397^A 0.00981^C 0.00889^C 2-methylpropyl

acetate 0.0189^B 0.0204^B 0.0587^A 0.0235^B 0.0198^B

butyl acetate 0.00222^B 0.00373^B 0.00982^A 0.00344^B 0.00245^B pentyl acetate 0.0376^A 0.0102^AB 0.000723^B 0.0296^A 0.00393^AB

2-ethylhexyl acetate nd^B nd^B 0.00154^A nd^B nd^B

ethyl phenylacetate 0.0663^A 0.0748^A 0.0157^C 0.0338^B 0.0389^B phenylethyl acetate 1.23^B 0.483^D 3.33^A 0.831^C 0.859^C

geometric means (n=3)

octanoate 0.00244^C 0.00206^C 0.00815^A 0.00171^C 0.00446^B ethyl

2-methylpropanoate 0.00719^A 0.00519^AB 0.00176^C 0.00496^AB 0.00422^B 2-methylpropyl

octanoate 0.000512^B 0.000476^B 0.00674^A 0.000612^B 0.000931^B ethyl 2-furoate 0.00732^A 0.00858^A 0.000600^B 0.00502^A 0.00585^A ethyl

3-methylbutanoate 0.0249^A 0.0193^AB 0.00670^C 0.0136^B 0.017^B diethyl succinate 0.160^AB 0.181^A 0.0884^C 0.13^B 0.135^B

carboxylic acids

acetic acid 0.515^B 0.474^B 2.38^A 0.369^B 0.481^B

butanoic acid 0.0580^C 0.0801^B 0.202^A 0.0551^C 0.0825^B

hexanoic acid 0.883^B 1.08^B 1.50^A 0.986^B 0.959^B

octanoic acid 1.01^A 0.828^A 0.252^B 1.00^A 1.17^A

2-methylpropanoic

acid 0.0498^BC 0.0672^AB 0.0803^A 0.0414^C 0.0596^ABC

terpenoids

neryl propanoate 0.0105^A 0.00801^AB 0.00676^B 0.00862^AB 0.00961^A geranyl acetate 0.0149^A 0.0151^A 0.0052^B 0.0153^A 0.0126^A β-citronellol 0.0322^B 0.0415^A 0.00852^D 0.0304^B 0.026^C nerol 0.00105^AB 0.0016^A 0.000186^C 0.000565^B 0.000969^AB

geraniol 0.0152^A 0.015^A 0.00476^B 0.0117^A 0.0139^A

α-farnesene isomer 0.000878^A 0.000961^A nd^C 0.00162^A 0.000297^B β-farnesene 0.0025^A 0.00242^A 0.00266^A 0.00312^A 0.00123^B nerolidol 0.0107^A 0.0109^A 0.000352^C 0.0128^A 0.00568^B cadalene 0.000258^A 0.000722^A

0.0000624

B 0.00051^A 0.000489^A

nor-isoprenoids

β-damascenone 0.0768^A 0.0820^A 0.00155^B 0.0743^A 0.0403^A

aromatics

phenol 0.00540^A 0.00524^A 0.00461^A 0.00345^B 0.00414^AB benzyl alcohol 0.00361^E 0.0214^A 0.00945^B 0.00709^C 0.00534^D

2-phenylethanol 29.5^B 34.6^A 18.9^C 16.1^D 20.8^C

benzaldehyde 0.0439^B 0.111^A 0.113^A 0.0394^B 0.0551^B

2.3.1.2.2.3. Principal component analysis (PCA) of the volatile profiles obtained from the Cabernet Sauvignon wines made from berry tissues

To better visualise relationships between the berry tissues used in the fermentations

on compounds that were found to be significantly different amongst the wines by the ANOVA. The first two principal components were able to explain a combined 82.36 % of the total variance, with PC-1 explaining 64.04 %, and PC-2 explaining 18.32 %. The next two principal components explained 9.81 % (PC-3) and 7.83 % (PC-4) of the total variance respectively, and were therefore not considered to be of great importance to understanding the relationship between the samples. A projection of volatile

components onto the factor space of the first two principal components is shown in Figure 8.

Wines made with seed tissue had high positive PC-1 scores and are located on the extreme right-hand side of the biplot (Figure 8). Compounds with high positive PC-1 loadings were ethyl esters (ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, and ethyl tetradecanoate), phenylethyl esters (2-phenylethyl acetate and 2-phenylethyl octanoate), isoamyl esters

(3-methylbutyl acetate and 3-(3-methylbutyl octanoate), carboxylic acids (acetic acid, butanoic acid, and hexanoic acid), butanediols (rac-2,3-butanediol and meso-2,3-butanediol), other esters (butyl acetate, 2-methylpropyl acetate, 2-methylpropyl octanoate, 2-ethylhexyl acetate), (E)-2-heptenal, and 1-octen-3-ol.

Wines made with skin tissue had high negative PC-1 scores and high positive PC-2 scores. As such, they are found in the upper left had side of the bi-plot (Figure 8).

Compounds with high negative PC-1 loadings (p-value<0.05) were β-damascenone, monoterpenoids (geraniol, geranyl acetate, β-citronellol), decanol, 2-nonanol, 3-octanone, diethyl succinate, ethyl 2-furoate, ethyl 2-methylpropanoate, hexyl acetate, and nerolidol. Compounds with high positive PC-2 loadings (p-value<0.05) were (Z)-3-hexenol butanol, heptanol, and benzyl alcohol. As a group, the monoterpenes stand out in this analysis as they have both high negative PC-1 and positive PC-2 loadings and are most associated with the wines produced from skins. The same is true for the C6

alcohols hexanol, (E)-3-hexenol and (Z)-3-hexenol, and the nor-isoprenoids vitispirane 1 and Riesling acetal as well as nonanol and decanol (Figure 8).

Wines made with flesh had high negative PC-2 scores.

Figure 8: PCA bi-plot EW Cabernet Sauvignon wines and grape influenced aroma compounds.

Abbreviations used in this figure are tabulated with their compound names in Table 11.

In document Contribution of grape berry lipids to wine aroma (Page 85-102)