Modelling Smoke Flavour in Wine from Chemical Composition of Smoke-Exposed Grapes and Wine

Table 4

Partial least squares regression coefficients of the predictive model for smoke flavour in wine from volatile phenols and phenolic glycosides in grapes for two studies, each comprising three cultivars. Variables identified as significant by the Martens and Martens jack-knife cross-validation method are highlighted in bold.

	Chardonnay Study A	Chardonnay Study B	Pinot Noir Study A	Pinot Noir Study B	Shiraz Study A	Shiraz Study B
Number of factors	2	2	3	7	1	1
SE	0.68	0.87	0.83	0.58	1.1	0.75
R^2	0.71	0.86	0.99	0.99	0.88	0.88
4-Methylguaiacol	0.07	0.26	0.08	0.18	0.09	0.08
Guaiacol	0.22	0.25	0.33	1.48	0.09	0.08
o-Cresol	0.37	0.19	0.09	−0.60	0.10	0.08
m-Cresol	0.39	0.28	0.58	−0.25	0.10	0.08
p-Cresol	0.39	0.19	0.46	−0.54	0.08	0.06
Syringol	NA	NA	NA	NA	NA	0.04
Sum of volatile phenols	0.29	0.23	0.29	0.47	0.09	0.08
GuRG	−0.26	0.05	−0.39	0.41	0.07	0.08
MGuRG	−0.06	0.02	−0.19	0.44	0.08	0.08
MSyGG	−0.32	−0.04	0.03	−0.21	0.09	0.08
PhRG	−0.04	0.02	−0.16	0.01	0.04	0.07
CrRG	−0.04	0.04	−0.03	−0.11	0.05	0.06
SyGG	−0.17	0.01	−0.05	−0.28	0.09	0.08
Sum of phenolic glycosides	−0.17	0.01	−0.08	−0.13	0.09	0.08

SE = standard error of cross-validation, GuRG, guaiacol rutinoside; MGuRG, methylguaiacol rutinoside; MSyGG, methylsyringol gentiobioside; PhRG, phenol rutinoside; CrRG, cresol rutinosides; SyGG, syringol gentiobioside. Where analytes were not detected in the sample set, they are absent from the PLS model, and denoted NA. 4-methylsyringol was not listed in the table due to no detection. Note, the sum of volatile phenols includes the seven volatile phenols listed in the table and sum of phenolic glycosides includes the six phenolic glycosides listed in the table.