Relationship between oxidation of wine phenols and wine quality: effects of phenol oxidation on pigment decolorization and haze formation in red wines, and on their functionality

1.葡萄蛋白对葡萄酒混浊形成的影响研究了两个红葡萄品种、四个白葡萄品种(Koshu、Semillon、Chardonnay、Riesling、Cabernet Sauvinon和Muscat Bailey A)的汁液、种子和果皮中游离氨基酸、多肽和蛋白质的含量。果实成熟期果汁中游离氨基酸总量因品种而异，在19oBrix时变化范围为400~2230 mg/L。可溶性蛋白质含量在10 0~5 0 0 mg/L之间，其中赛美龙葡萄汁含量最高。从种子中提取的游离氨基酸含量不到1 mg/g，蛋白质含量在20~40 mg/g之间，果皮中游离氨基酸含量很少，蛋白质含量在1~5 mg/g之间。赤霞珠和麝香A这两个红葡萄酒品种的蛋白质含量较低，很难从它们的果汁或葡萄酒中获得蛋白质，经…电泳法分级更多的还不够。另一方面，塞米隆葡萄的蛋白质含量很高，因此在接下来的实验中，塞米隆葡萄汁和葡萄酒的发酵方式与酿造自由酿造红葡萄酒的方法相同。在果汁和自由酿酒中，蛋白质在蛋白质组分(冻干物)中的比例约为90%，而在皮酒中约为45%(其余化合物主要为糖)。用凝胶电泳法对蛋白质组分进行分级。果汁和自酿葡萄酒蛋白质组分的电泳谱非常相似，但与在皮肤上发酵的葡萄酒蛋白质组分有很大的不同。将蛋白质和种子酚混合在类似葡萄酒的模型溶液中，并让混合物放置12小时。离心后，取上清液进行高效液相色谱分析。2.葡萄多酚氧化酶的分离和纯化利用不同的柱层析对葡萄多酚氧化酶进行分离和纯化，研究了葡萄多酚氧化酶的酶学性质和化学性质。多酚氧化酶的相对分子质量约为40 kDa，最适pH为6.3。较少

1. Effect of grape proteins on haze formation in wineThe contents of free amino acids, peptides, and proteins in the juices, seeds, and skins from two red and four white grape varieties (Koshu, Semillon, Chardonnay, Riesling, Cabernet Sauvignon, and Muscat Bailey A) were investigated. In the juices, total free amino acids varied with the variety, ranging from 400 to 2230 mg/L at 19oBrix during berry ripening. The soluble protein content ranged from 100 to 500 mg/L, with Semillon grape juice containing the highest amount among six varieties. Less than 1 mg/g of free amino acids was extracted from seeds, and proteins were obtained in the range between 20 and 40 mg/g. The free amino acid content in skins was small, and the amounts of proteins extracted ranged from 1 to 5 mg/g.Since the protein concentrations are low in Cabernet Sauvignon and Muscat Bailey A, which are red wine varieties, it was difficult to obtain proteins from their juice or wine and fractionation by electrophoresis was … More not sufficient. On the other hand, Semillon grape have a high protein content, so in the following experiments, protein were prepared from Semillon grape juice and wines fermented in the same ways as those used to make free-run and red wines.Proteins were fractionated from juice and two wines using salting-out precipitation with ammonium sulfate and HPLC on Superdex 75HR. The proportions of proteins in the protein fractions (lyophilisates) were about 90% in the cases of the juice and free-run wine and about 45% for the wine fermented on skins (the remaining compounds were mostly sugars). The protein fractions were fractionated by gel electrophoresis. The electrophoretic patterns of the juice and free-run wine protein fractions were very similar to each other but very different from that of the fraction from wine fermented on skins.Haze formation was investigated using the protein fractions mentioned above. Proteins and seed phenols were mixed in wine-like model solutions and the mixtures were allowed to stand for 12 hours. They were the centrifuged and the supernatants obtained were analyzed by HPLC. Haze formation differed with the protein judging from HPLC patters (protein peaks) obtained:2. Fractionation and purification of grape polyphenol oxidasesPolyphenoloxidases, by which phenolic compounds were readily bound to proteins to form haze, were fractionated and purified by various column chromatographies and their enzymatic and chemical properties were investigated. The molecular weight of a polyphenoloxidase was about 40 kDa, and its optimum pH was 6.3. Less