Influence of berry ripeness on concentration, qualitative composition and extractability of grape seed tannins
Influence of berry ripeness on concentration, qualitative composition and extractability of grape seed tannins
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DOI：
10.1111/j.1755-0238.2012.00178.x
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发表时间：
2012-01-01
影响因子：
2.8
通讯作者：
Gomez-Plaza, E.
中科院分区：
文献类型：
--
作者：
Bautista-Ortin, A. B.;Rodriguez-Rodriguez, P.;Gomez-Plaza, E.
背景和目标：在同一个葡萄园种植的三个葡萄品种的种子单宁的演变，从preveraison到收获，以确定其积累模式。此外，为了阐明使用70%丙酮作为提取溶剂是否高估了发酵过程中会发生的情况，在整个成熟期内用一种方法提取了种子单宁，该方法涉及用12.5%乙醇水溶液提取3天，并将结果与丙酮提取方法进行了比较。方法和结果：对于这两种方法，在过量间苯三酚的存在下，酸催化后分析提取的单宁。种子单宁达到了最大的veraison和成熟度下降，平均聚合度（mDP）在研究期间只有轻微的变化。当用12.5%乙醇提取单宁时，其浓度在成熟的第一部分比使用丙酮高得多，但在收获时显着降低。结论：两种溶剂在成熟过程中可提取的种子单宁减少。单宁的浓度与两种溶剂中观察到的差异可能是由于在成熟过程中发生在种子中的组织化学变化。本研究的意义：用两种不同方法观察到的单宁浓度的差异可能表明，当果肉成熟度在种子成熟之前达到时，发酵溶液将比丙酮方法提取更多的单宁。这些结果表明，在监测种子成熟度时，提取方法对于预测葡萄酒中的种子单宁具有重要意义。
Background and Aims: The evolution of seed tannins in three grape varieties grown in the same vineyard was followed from preveraison to harvest, to determine their pattern of accumulation. Also, to elucidate whether the use of 70% acetone as extracting solvent overestimate what will occur during fermentation, seed tannins were extracted throughout the ripening period with a method that involved a 3 days extraction with aqueous 12.5% ethanol and the results compared with the acetone extraction method. Methods and Results: For both methods, the extracted tannins were analysed following acid-catalysis in the presence of excess of phloroglucinol. Seed tannins reached a maximum around veraison and decreased towards maturity, the mean degree of polymerization (mDP) varying only slightly during the studied period. When tannins were extracted with 12.5% ethanol, their concentration was much higher during the first part of the maturation than using acetone but was significantly lower at harvest. Conclusions: The decrease in extractable seed tannins during ripening was observed with both solvents. The differences observed in the concentration of tannins with both solvents could be due to the histochemical changes occurring in seeds during maturation. Significance of the Study: The differences observed in tannin concentration with the two different methods may indicate that when pulp maturity is reached before seeds are ripe, the fermenting solution will extract more tannins than the acetone method. These results point to the importance of extraction methodology when monitoring seed maturity for the prediction of seed tannins in wine.