Table 4.
Individual polyphenols and furans (mg/L) in Malvasia wine during heating at 45 °C (3 months) and 70 °C (1 month).
| Malvasia | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 m | ± SD | 1 m, 45 °C | ± SD | 2 m, 45 °C | ± SD | 3 m, 45 °C | ± SD | 1 m, 70 °C | ± SD | ||
| Non-flavonoids | |||||||||||
| Hydroxybenzoics | |||||||||||
| Gallic acid | 11.62a | 0.42 | 13.73bc | 0.07 | 13.85b | 0.02 | 13.27cd | 0.08 | 12.93d | 0.12 | |
| Protocatechuic acid | 3.40a | 0.01 | 2.67b | 0.15 | 2.66b | 0.03 | 2.95c | 0.05 | 3.48a | 0.15 | |
| p-Hydroxybenzoic acid | 0.92a | 0.03 | 0.88a | 0.04 | 0.68b | 0.03 | 0.61c | 0.01 | 0.90a | 0.01 | |
| Vanillic acid | 1.71a | 0.03 | 0.93b | 0.04 | 0.66c | 0.01 | 0.57d | 0.02 | 0.55d | 0.01 | |
| Syringic acid | n.d. | n.d. | n.d. | 0.93a | 0.05 | 0.75b | 0.03 | ||||
| Ellagic acid | n.d. | n.d. | n.d. | n.d. | n.d. | ||||||
| Total | 17.66 | 18.21 | 17.85 | 18.33 | 18.61 | ||||||
| Hydroxycinnamates | |||||||||||
| trans-Caftaric acid | 37.33a | 0.07 | 30.47b | 0.02 | 23.31c | 0.02 | 16.87d | 0.02 | 7.25e | 0.04 | |
| cis-Coutaric acid | 7.40a | 0.03 | 6.32b | 0.02 | 5.28c | 0.31 | 3.91d | 0.13 | 0.93e | 0.00 | |
| trans-Coutaric acid | 15.51a | 0.08 | 13.27b | 0.06 | 10.76c | 0.01 | 8.20d | 0.04 | 4.88e | 0.00 | |
| trans-Fertaric acid | 3.08a | 0.05 | 2.71b | 0.16 | 2.14c | 0.03 | 1.60d | 0.02 | 0.86e | 0.02 | |
| Unk 5 * | 0.62a | 0.01 | 0.48b | 0.01 | n.q. | n.q. | n.d. | ||||
| Caffeic acid | 1.71a | 0.03 | 3.10b | 0.02 | 3.60c | 0.02 | 3.55d | 0.05 | 6.72e | 0.02 | |
| Unk 6 * | n.d. | n.d. | n.d. | n.d. | n.d. | ||||||
| p-Coumaric acid | 0.76a | 0.01 | 1.35b | 0.00 | 1.63c | 0.02 | 1.65c | 0.05 | 7.72d | 0.09 | |
| Ferulic acid | 0.37a | 0.02 | 0.66b | 0.01 | 0.72c | 0.04 | 0.62b | 0.01 | 1.00d | 0.02 | |
| Total | 66.77 | 58.36 | 47.42 | 36.39 | 29.36 | ||||||
| Stilbene | |||||||||||
| trans-Resveratrol | n.q. | n.q. | n.q. | n.d. | n.d. | ||||||
| Flavonoids | |||||||||||
| Flavonols | |||||||||||
| Unk 7 ** | 7.25a | 0.07 | 6.80b | 0.11 | 5.31c | 0.18 | 3.79d | 0.06 | 0.48e | 0.03 | |
| Myricetin | n.d. | n.d. | n.d. | n.d. | n.d. | ||||||
| Quercetin | 0.64a | 0.01 | 0.96b | 0.01 | 0.85c | 0.00 | 0.65a | 0.01 | 0.75d | 0.01 | |
| Kaempferol | n.q. | n.q. | n.q. | n.q. | n.q. | ||||||
| Total | 7.89 | 7.76 | 6.17 | 4.44 | 1.24 | ||||||
| Flavan-3-ols | |||||||||||
| (−)-Epigallocatechin | 0.55a | 0.01 | n.q. | n.q. | n.q. | 0.60b | 0.02 | ||||
| (+)-Catechin | 6.98a | 0.05 | 4.23b | 0.06 | 1.25c | 0.03 | 0.49d | 0.02 | n.q. | ||
| (−)-Epicatechin | 1.47a | 0.04 | 0.90b | 0.02 | 0.49c | 0.03 | 0.39d | 0.01 | 0.37d | 0.02 | |
| Total | 9.00 | 5.12 | 1.74 | 0.88 | 0.97 | ||||||
| Furans | |||||||||||
| HMF | 1.48a | 0.00 | 12.17b | 0.01 | 30.42c | 0.01 | 52.10d | 0.15 | 1651.50e | 2.78 | |
| Furfural | n.d. | n.q. | 1.80a | 0.02 | 2.33b | 0.05 | 19.48c | 0.01 | |||
| Total | 1.48 | 12.17 | 32.22 | 54.43 | 1670.98 | ||||||
* Quantification relative to caffeic acid; ** Quantification relative to rutin; n.d. - not detected, bellow LOD; n.q. - not quantified, bellow LOQ; HMF - 5-hydroxymethylfurfural; Different letters in the same row (in bold) means that there are significant differences at p < 0.050.