| Oxidative browning is a serious problem in wine industry, which mostly affects thequality and nutrient values of wine. In this study, employing an accelerated oxidation test anda natural oxidation test, the oxidation stability and antioxidant activity of “Meili” wine fromdifferent brewing techniques were investigated, as well as Merlot dry red wine （the control）,so as to provide a reference for the promotion, development and application of “Meili” grapein future. The main results of this study are as follows:1. During the accelerated oxidation of30days, the browning degrees（A420nm） of Meiliwines except for the Meili sparkling wine, firstly presented a quick rise and a rapid fall, andthen rose slowly, but it appeared to have a decline at the end of the test （the30days）. Over theperiod of30days, browning development was shown to obey quadratic equation model fromthe seventh day of the treatment, and the initial browning rate of wines after7days were:Meili red wine(29.0×10-3/d)> Meili rose wine(12.0×10-3/d)> Meili sparklingwine（2.4×10-3/d）, which were all less than Merlot red wine （101.4×10-3/d）. During the naturaloxidation of wines, the overall changing trends of wine browning degree are similar to thoseduring the accelerated oxidation.2. The correlation analysis between variation of the main parameters and browningdegree （△A420nm） throughout the accelerated oxidation showed that there was a markedlynegative correlation （R=-0.98, P <0.01） between the variation of browning degree and freesulfur dioxide variation, and a significantly negative correlation （R=-0.96, P<0.05） betweenthe variation of browning degree and gallic acid variation, and a markedly negativecorrelation between the variation of browning degree and respectively catechinvariation（R=-0.98, P <0.01）, epicatechin variation （R=-0.96, P <0.01）, trans-resveratrolvariation（R=-0.98, P <0.01）, as well as a marked correlation between the variation ofbrowning degree and respectively syringic acid variation （R=0.98, P <0.01）, p-coumaric acidvariation（R=0.99, P <0.01）, quercetin variation（R=0.98, P <0.01）. And over the naturaloxidation process, the wine browning degrees were related with pH, free sulfur dioxide, totalphenol.3. Through measuring the antioxidant activity of wines during the oxidation, the resultsshowed that, the ability of scavenging free radicals by ABTS slowly droped with time, theorder of their scavenging capacity was: Meili rose wine （56.0）> Meili sparkling wine （27.8）> Meili red wine （25.3）> Merlot red wine （10.7）. The ability of scavenging free radicals byDPPH also slowly droped with time, and the order was: Meili rose wine （237.2）> Meili redwine （129.8）> Merlot red wine （75.0）> Meili sparkling wine （12.3）. However, during thenatural oxidation, the ability of scavenging free radicals by ABTS and DPPH slowlyincreased with time, this may be caused by the short time of natural oxidation.4. The correlation analysis of wine antioxidant activity and the main parameters showedthat, there was a significant correlation between browning degree （A420nm） and scavengingfree radicals ability of ABTS. While when using DPPH method to determine the wineantioxidant activity, there was a significant correlation between DPPH scavenging freeradicals ability and gallic acid （R=0.91，P＜0.05）, and total phenol （R=0.95，P＜0.05）,and browning degree（A420nm）（R=0.98，P＜0.01）. In addition, there was also a markedcorrelation between ABTS method and DPPH method （R=0.97, P<0.01）.5. The results of the analysis of chemical index and the sensory evaluation suggested that,the physical-chemical and sensory attributes of Meili wines reduced after oxidation browning.In particular, colour became brown, aroma depressed and was not rich, with typical oxidationsmell of honey and boiled vegetables appearing.In conclusion, considering the browning degree, antioxidant activity and the qualityindex analysis, Meili wines’ antioxidant properties are greater than Merlot dry red wine, andMeili grape seems to be more appropriate for brewing rose wine and sparkling wine. |
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