| Kiwi wine is a complex mixture of bioactive compounds with positive health effects,and its composition is influenced by some technological variables. Polyphenols include two main classes of compounds, namely flavonoids and nonflavonoids. Polysaccharide in kiwi wine is generally assumed to originate from fruits and yeasts, independent of bacterial metabolism, except for the action of certain spoilage species. These compounds can directly contribute to several characteristics of kiwi wine, mainly colloidal and foam stability, sensory properties, such as flavour and aroma.Different kiwi fruit varieties from Shaanxi province(Xu Xiang, Cui Xiang, Hort and Hua You) were used to elaborate kiwi wines following wine making process. The aim of this work was to evaluate the changes of phenolic compounds, antioxidant activities,polysaccharides during fermentation and ageing and analyze volatile compounds of kiwi wines.(1) Four kiwi wines showed strong antioxidant capacity, which could partly be explained by the change of total phenolic. However, there were significant differences between different varieties, which may require further study of other substances in the kiwi wine, for example, amino acids, peptides, maillard product. There were significant differences between in vitro antioxidant capacities. HY kiwi wine showed the highest total phenolic content and strongest antioxidant capacity during fermentation and ageing.(2) Caffeic acid, epicatechin, gallic acid and caffeic acid were the main polyphenols of kiwi wines, followed by protocatechuic acid and ellagic acid. The content of p-coumaric acid,ferulic acid, chlorogenic acid, and hyperin were relatively lower.(3) The changes of phenolic compounds during kiwi wine ageing were similar. After the ageing 180 d, the main phenolic compounds of kiwi wine showed no difference, but the content of phenolic compounds in HY wine were significantly higher than other kiwi wines.The results showed that long period of ageing decreased the antioxidant potential in all samples. Antioxidant activities of kiwi wines were strictly correlated with phenolics such as gallic acid, catechin, protocatechuic acid, ferulic acid, chlorogenic acid, caffeic acid andphloridzin during ageing.(4) Mannose, galactose, glucose, xylcose, arabinose, rhamnose and galacturonic acid were detected in all analyzed kiwi wines; mannose being the most abundant carbohydrate,fowlled by galactose and arabinose in kiwi wines. Glucose and galactose content increased during ageing of these wines, and arabinose concentration lowered during ageing, whereas the content of polysaccharides presented the characteristics of first increasing and then decreasing during kiwi wine ageing. After ninety days of ageing the highest content of monosaccharides and polysaccharides of kiwi wines were obtained.(5) The volatile compounds of kiwi wine were analyzed by Headspace Solid-Phase Microextraction coupled with Gas Chromatography Mass Spectrometry. The results showed that 70 compounds were identified in kiwi wines, in which esters, alcohols, acids, aldehydes,ketones and terpenes were the major compounds. According to OAVs, isobutanol, isoamyl alcohol, n-hexanol, ethyl acetate, isoamyl acetate, ethyl caproate, hexyl acetate, ethyl caprylate, ethyl caprate and octoic acid. |
