Cyprus University of Technology, Department of Agricultural Sciences, Biotechnology and Food Science, Lemesos 3603, Cyprus.
Department of Analytical Chemistry, University of Granada, c/Fuentenueva s/n, 18071 Granada, Spain; Research and Development of Functional Food Centre (CIDAF), Granada, Spain.
Food Res Int. 2017 Oct;100(Pt 3):469-476. doi: 10.1016/j.foodres.2016.11.015. Epub 2016 Nov 24.
Grapes's sun-dried process is one of the most critical steps in the production of 'Commandaria', a dessert wine product that is exclusively produced in Cyprus and derived from must obtained from two indigenous grape cultivars, namely 'Mavro' and 'Xynisteri'. Despite its significant economic importance, no data regarding the primary and secondary metabolites of the aforementioned cultivars exist. Thus, in the current study, the effect of sun drying process on the qualitative attributes and phenolic profile of 'Mavro' and 'Xynisteri' musts was dissected. Musts were analyzed at harvest and at the end of the sun-drying process that corresponds to ca. 30-40% water loss. Results highlighted significant differences in chemical composition of the must before and after the sun-drying process. Except for the increase of soluble solids content, a significant increment in glucose, fructose, total acidity, total phenols and total flavonoids contents was monitored. Subsequently, forty-two phenolic compounds were identified by LC-DAD-qTOF-MS revealing the polyphenolic fingerprint of the two cultivars. Results also indicated that changes in the phenolic composition of the obtained must are not only correlated with the dehydration effect, but both synthesis or degradation reactions occurred. In particular, the increases in the concentration of hydroxybenzoic acids were higher than the concentration effect for both cultivars. Regarding to hydroxycinnamates, dehydration caused a six-fold increase of hydroxycinnamic acid content in both cultivars. Intriguingly, the concentration of some hydroxycinnamic acids such as caffeic acid dihexoside and fertaric acid isomer went descending. Although the degradation of the internal side of the skin facilitate improved extractability from the skins to the grape pulp and therefore to the grape must, the sun-drying process may also induced stilbene and lignans synthesis production. A significant effect of dehydration on the postharvest biosynthesis of three groups of flavonoids (flavonols, flavan-3-ols, flavanonols), was also observed. This study sheds some light in the substantial changes that occur in specific metabolites during the sun drying process; such metabolites can be considered as potential factors that may determine organoleptic characteristics and biological properties of the end-product.
葡萄的晒干过程是“Commandaria”生产过程中最关键的步骤之一，这是一种仅在塞浦路斯生产的甜酒，源自两种本土葡萄品种的葡萄汁，即“Mavro”和“Xynisteri”。尽管它具有重要的经济意义，但关于上述品种的主要和次要代谢物的数据尚不存在。因此，在本研究中，分析了晒干过程对“Mavro”和“Xynisteri”葡萄汁的定性属性和酚类谱的影响。在收获时和晒干过程结束时（大约损失 30-40%的水分）分析了葡萄汁。结果突出了晒干过程前后葡萄汁化学成分的显著差异。除了可溶性固形物含量增加外，还监测到葡萄糖、果糖、总酸度、总酚和总类黄酮含量的显著增加。随后，通过 LC-DAD-qTOF-MS 鉴定出 42 种酚类化合物，揭示了两种品种的多酚指纹图谱。结果还表明，获得的葡萄汁中酚类成分的变化不仅与脱水作用有关，而且还发生了合成或降解反应。特别是，两种品种的羟基苯甲酸浓度增加均高于浓度效应。关于羟基肉桂酸，脱水导致两种品种的羟基肉桂酸含量增加了六倍。有趣的是，一些羟基肉桂酸如咖啡酸二己糖苷和 feraric 酸异构体的浓度下降。尽管内部果皮的降解有助于从果皮向葡萄果肉和葡萄汁中更好地提取，但晒干过程也可能诱导芪和木脂素的合成。还观察到脱水对三类黄酮（黄酮醇、黄烷醇、黄烷酮醇）的采后生物合成有显著影响。本研究揭示了在晒干过程中特定代谢物发生的实质性变化；这些代谢物可以被认为是可能决定最终产品感官特征和生物特性的潜在因素。
