Table 2.
Volatile compounds and concentration (mg/L) with standard deviation (SD) of ‘Italian Riesling’ icewine samples.
| Compounds | RI DB-WAX |
C mg/L ± SD |
BT mg/L ± SD |
SP mg/L ± SD |
CF mg/L ± SD |
MF mg/L ± SD |
|---|---|---|---|---|---|---|
| Esters | ||||||
| Ethyl acetate | 883 | 4.498 ± 0.065 a | 3.453 ± 0.144 c | 4.465 ± 0.115 a | 4.052 ± 0.116 b | 3.141 ± 0.064 d |
| Isobutyl acetate | 1006 | 0.002 ± 0.000 a | 0.001 ± 0.000 d | 0.002 ± 0.000 b | 0.001 ± 0.000 c | ND |
| Ethyl butyrate | 1044 | 0.049 ± 0.002 a | 0.027 ± 0.001 e | 0.042 ± 0.001 c | 0.046 ± 0.001 b | 0.034 ± 0.002 d |
| Isoamyl acetate | 1120 | 0.493 ± 0.012 a | 0.353 ± 0.006 c | 0.463 ± 0.007 b | 0.449 ± 0.028 b | 0.330 ± 0.007 c |
| Ethyl hexanoate | 1232 | 2.697 ± 0.085 a | 1.356 ± 0.074 c | 2.142 ± 0.120 b | 2.158 ± 0.061 b | 0.568 ± 0.023 d |
| Ethyl (E)-hex-2-enoate | 1245 | 0.040 ± 0.001 a | 0.021 ± 0.001 c | 0.038 ± 0.001 b | 0.036 ± 0.004 b | ND |
| Ethyl heptanoate | 1332 | 0.045 ± 0.001 a | 0.016 ± 0.001 d | 0.034 ± 0.001 b | 0.029 ± 0.002 c | 0.003 ± 0.001 e |
| Ethyl octanoate | 1434 | 2.870 ± 0.080 a | 0.768 ± 0.022 c | 1.706 ± 0.086 b | 1.790 ± 0.140 b | 0.574 ± 0.027 d |
| Ethyl nonanoate | 1530 | 0.005 ± 0.000 a | ND | 0.002 ± 0.000 b | ND | ND |
| Ethyl decanoate | 1638 | 1.737 ± 0.026 a | 0.758 ± 0.013 d | 1.249 ± 0.039 b | 1.023 ± 0.05 c | 0.27 ± 0.034 e |
| Ethyl benzoate | 1644 | 0.028 ± 0.001 a | 0.021 ± 0.001 c | 0.028 ± 0.002 ab | 0.027 ± 0.001 b | ND |
| Diethyl succinate | 1687 | 0.773 ± 0.009 a | 0.653 ± 0.023 c | 0.726 ± 0.017 b | 0.717 ± 0.030 b | 0.695 ± 0.036 bc |
| Ethyl phenylacetate | 1776 | 0.019 ± 0.002 a | 0.014 ± 0.001 b | 0.015 ± 0.001 b | 0.018 ± 0.001 a | ND |
| Phenethyl acetate | 1825 | 0.092 ± 0.001 a | 0.090 ± 0.003 a | 0.089 ± 0.004 a | 0.088 ± 0.003 a | 0.034 ± 0.001 b |
| Ethyl dodecanoate | 1847 | 0.727 ± 0.026 a | 0.444 ± 0.023 c | 0.655 ± 0.033 b | 0.377 ± 0.017 d | 0.075 ± 0.007 e |
| Ethyl 3-phenylpropionate | 1914 | 0.010 ± 0.001 a | 0.007 ± 0.001 b | 0.010 ± 0.001 a | 0.010 ± 0.002 a | ND |
| Ethyl myristate | 2043 | 0.216 ± 0.018 a | 0.126 ± 0.015 b | 0.205 ± 0.007 a | 0.142 ± 0.012 b | 0.032 ± 0.002 c |
| Diethyl malate | 2060 | 0.029 ± 0.001 a | ND | 0.028 ± 0.001 ab | 0.026 ± 0.003 bc | 0.024 ± 0.001 c |
| Ethyl hexadecanoate | 2243 | 0.134 ± 0.005 a | 0.13 ± 0.009 ab | 0.123 ± 0.001 b | 0.109 ± 0.006 c | 0.040 ± 0.001 d |
| δ-Dodecalactone | 2438 | 0.044 ± 0.001 a | 0.039 ± 0.002 bc | 0.037 ± 0.001 c | 0.042 ± 0.003 ab | ND |
| Subtotal | 14.508 ± 0.162 a | 8.274 ± 0.176 d | 12.058 ± 0.235 b | 11.141 ± 0.420 c | 5.821 ± 0.162 e | |
| Alcohols | ||||||
| Isobutanol | 1077 | 0.109 ± 0.001 a | 0.091 ± 0.002 b | 0.109 ± 0.003 a | 0.104 ± 0.004 a | 0.084 ± 0.005 c |
| n-Butanol | 1150 | 0.018 ± 0.001 a | 0.010 ± 0.001 bc | 0.011 ± 0.001 b | 0.009 ± 0.001 c | 0.010 ± 0.001 bc |
| 1-Pentanol | 1255 | 5.989 ± 0.008 a | 5.558 ± 0.181 c | 5.980 ± 0.105 a | 5.778 ± 0.023 b | 4.910 ± 0.124 d |
| 3-Methyl-1-pentanol | 1318 | 0.006 ± 0.001 a | 0.005 ± 0.000 b | 0.005 ± 0.000 b | 0.006 ± 0.000 a | 0.004 ± 0.000 c |
| 1-Hexanol | 1353 | 1.098 ± 0.011 a | 1.117 ± 0.038 a | 1.081 ± 0.035 a | 1.064 ± 0.033 a | 0.819 ± 0.018 b |
| cis-3-Hexen-1-ol | 1366 | 0.067 ± 0.001 a | 0.059 ± 0.002 b | 0.066 ± 0.001 a | 0.065 ± 0.005 a | 0.035 ± 0.002 c |
| 1-Octen-3-ol | 1447 | 0.147 ± 0.012 a | 0.141 ± 0.012 a | ND | 0.146 ± 0.006 a | 0.067 ± 0.007 b |
| Heptanol | 1449 | 0.064 ± 0.001 a | 0.053 ± 0.003 c | ND | 0.064 ± 0.002 a | 0.058 ± 0.003 b |
| 1-Octanol | 1554 | 0.052 ± 0.001 a | 0.052 ± 0.004 a | 0.047 ± 0.001 a | 0.050 ± 0.006 a | 0.045 ± 0.003 a |
| 2,3-Butanediol | 1556 | 0.047 ± 0.002 a | 0.042 ± 0.002 b | ND | 0.046 ± 0.004 a | ND |
| Nonanol | 1666 | 0.019 ± 0.001 a | 0.014 ± 0.001 b | 0.015 ± 0.001 b | 0.019 ± 0.001 a | ND |
| Decanol | 1769 | 0.022 ± 0.001 a | ND | 0.021 ± 0.001 a | 0.021 ± 0.001 a | 0.020 ± 0.001 b |
| Phenethyl alcohol | 1912 | 2.740 ± 0.010 a | 2.719 ± 0.099 a | 2.685 ± 0.111 a | 2.569 ± 0.219 a | 2.312 ± 0.085 b |
| Dodecanol | 1970 | 0.016 ± 0.001 a | 0.016 ± 0.001 a | 0.014 ± 0.001 b | 0.016 ± 0.001 a | 0.015 ± 0.001 a |
| Subtotal | 10.393 ± 0.031 a | 9.876 ± 0.312 b | 10.033 ± 0.211 ab | 9.956 ± 0.235 b | 8.379 ± 0.240 c | |
| Acids | ||||||
| Acetic acid∗ | 1452 | 0.621 ± 0.018 a | 0.593 ± 0.013 a | 0.606 ± 0.016 a | 0.603 ± 0.078 a | 0.451 ± 0.022 b |
| Isobutanoic acid | 1581 | 0.012 ± 0.001 a | ND | 0.012 ± 0.001 a | 0.011 ± 0.001 ab | 0.010 ± 0.000 b |
| 2-Methyl butanoic acid | 1655 | 0.056 ± 0.001 a | 0.054 ± 0.001 ab | 0.052 ± 0.001 b | 0.056 ± 0.002 a | 0.052 ± 0.002 b |
| Hexanoic acid | 1851 | 0.652 ± 0.024 a | 0.617 ± 0.024 abc | 0.598 ± 0.029 bc | 0.640 ± 0.024 ab | 0.591 ± 0.017 c |
| Heptoic acid | 1960 | 0.029 ± 0.002 a | 0.027 ± 0.001 bc | 0.026 ± 0.001 bc | 0.028 ± 0.002 ab | 0.025 ± 0.001 c |
| Octanoic acid | 2050 | 1.237 ± 0.037 a | 1.091 ± 0.086 b | 1.060 ± 0.052 b | 1.122 ± 0.034 b | 0.797 ± 0.021 c |
| Nonanoic acid | 2169 | 0.036 ± 0.001 a | 0.016 ± 0.001 c | ND | 0.036 ± 0.002 a | 0.025 ± 0.001 b |
| Decanoic acid | 2279 | 0.757 ± 0.011 a | 0.596 ± 0.016 b | 0.506 ± 0.019 c | 0.745 ± 0.013 a | 0.109 ± 0.006 d |
| Dodecanoic acid | 2502 | 0.072 ± 0.001 a | ND | 0.035 ± 0.003 c | 0.069 ± 0.002 a | 0.064 ± 0.001 b |
| Subtotal | 3.399 ± 0.049 a | 2.994 ± 0.107 c | 2.860 ± 0.068 c | 3.241 ± 0.074 b | 2.061 ± 0.054 d | |
| Terpenes | ||||||
| Rose oxide | 1337 | 0.020 ± 0.001 a | ND | ND | ND | 0.005 ± 0.001 b |
| Linalool | 1552 | 0.501 ± 0.009 a | ND | 0.489 ± 0.003 ab | 0.402 ± 0.013 c | 0.477 ± 0.021 b |
| α-Terpineol | 1680 | 0.049 ± 0.002 a | 0.049 ± 0.001 ab | 0.045 ± 0.002 ab | 0.045 ± 0.003 ab | 0.045 ± 0.003 b |
| Citronellol | 1750 | 0.401 ± 0.009 a | 0.378 ± 0.025 a | 0.372 ± 0.015 a | 0.387 ± 0.013 a | 0.147 ± 0.009 b |
| Nerol | 1806 | 0.018 ± 0.000 a | 0.013 ± 0.001 b | 0.013 ± 0.000 b | 0.017 ± 0.001 a | 0.004 ± 0.001 c |
| Hydroxycitronellol | 1822 | 0.008 ± 0.001 a | ND | 0.008 ± 0.001 ab | 0.007 ± 0.001 bc | 0.007 ± 0.001 c |
| β-Damascenone | 1831 | 0.125 ± 0.006 a | 0.119 ± 0.009 a | 0.112 ± 0.005 a | 0.080 ± 0.009 b | 0.046 ± 0.004 c |
| Geranyl acetone | 1865 | 0.100 ± 0.002 a | 0.018 ± 0.000 c | 0.038 ± 0.007 b | 0.098 ± 0.019 a | 0.091 ± 0.002 a |
| Geranic acid | 2334 | 0.007 ± 0.001 a | 0.003 ± 0.000 c | 0.006 ± 0.001 b | 0.006 ± 0.001 b | ND |
| Subtotal | 1.227 ± 0.022 a | 0.582 ± 0.023 d | 1.083 ± 0.022 b | 1.041 ± 0.038 b | 0.823 ± 0.022 c | |
| carbonyls | ||||||
| 6-Methyl-5-hepten-2-one | 1341 | 0.023 ± 0.001 a | ND | ND | 0.021 ± 0.001 b | 0.021 ± 0.001 b |
| Oct-2-enal | 1434 | 0.025 ± 0.001 b | 0.025 ± 0.001 b | 0.027 ± 0.001 a | 0.017 ± 0.001 c | ND |
| Furfural | 1468 | 0.031 ± 0.001 ab | 0.033 ± 0.001 a | 0.029 ± 0.001 b | 0.008 ± 0.002 c | ND |
| Subtotal | 0.078 ± 0.001 a | 0.058 ± 0.001 b | 0.056 ± 0.001 b | 0.046 ± 0.002 c | 0.021 ± 0.001 d | |
| Volatile phenols | ||||||
| Eugenol | 2141 | 0.022 ± 0.001 a | ND | ND | 0.015 ± 0.004 b | ND |
| Guaiacol | 2203 | 0.043 ± 0.001 a | 0.031 ± 0.001 d | 0.038 ± 0.002 c | 0.041 ± 0.001 b | 0.011 ± 0.001 e |
| Subtotal | 0.065 ± 0.001 a | 0.031 ± 0.001 d | 0.038 ± 0.001 c | 0.056 ± 0.004 b | 0.011 ± 0.001 e |
Data are means ± SD (n = 3). Retention indices (RI) were reported in the NIST standard reference database. Different letters represent significant differences at a significant level of 0.05. “ND” means that the aroma component is not detected or in trace amount. * The concentration of Acetic acid was presented with g/L.