![]() ![]() These compounds include monoterpenes, C13-norisoprenoids, C6-compounds, methoxypyrazines and mercaptans. Some volatile compounds synthesized in grapes exist in volatile forms but mostly are non-volatile aroma precursors, which are released through biochemical and chemical reactions during fermentation and aging. The compounds derived from grapes provide varietal differentiation. The volatile compounds determining the aroma of wine originate from grapes (varietal aromas) and are secondary products of fermentation processes (fermentation aromas) and aging (post-fermentation aromas). It can be detected by volatile compound analysis. Varietal adulteration of wine is defined as the addition of must produced from grape varieties other than the labelled variety in illegal quantities. Moreover, the best SVM model (F-score of 1) was built with a subset containing 2-phenylethyl acetate and 3-(methylsulfanyl)propan-1-ol. An evaluation of the importance value of subsets consisting of six volatile compounds with the highest potential to distinguish between the Zweigelt and Rondo varieties revealed that SVM and kNN yielded the best classification models (F-score of 1, accuracy of 100%) when 3-ethyl-4-methylpentan-1-ol or 3,7-dimethyl-1,5,7-octatrien-3-ol (hotrienol) or subsets containing one or both of them were used. ![]() Both machine learning methods yielded models with the highest possible classification accuracy (100%) when the relative concentrations of all the test compounds or alcohols alone were used as input data. The relative concentrations of volatiles were used as an input data set, divided into two subsets (training and testing), to the support vector machine (SVM) and k-nearest neighbor (kNN) algorithms. 3,7-dimethyl-1,5,7-octatrien-3-ol (hotrienol) was found to be a variety marker for Zweigelt wines, since it was detected in all the Zweigelt wines, but was not present in the Rondo wines at all. ![]() Sixty-seven volatile compounds were tentatively identified in the test wines they represented several classes: 9 acids, 24 alcohols, 2 aldehydes, 19 esters, 2 furan compounds, 2 ketones, 1 sulfur compound and 8 terpenes. The wines were produced by using five commercial yeast strains and two types of malolactic fermentation. According to 3 percent, Russia will ultimately seize control of the entire country.Īsked if Poland should continue to admit Ukrainian refugees, 32 percent said "decidedly yes," 51 percent "rather yes," 9 percent "rather not" and 8 percent "decidedly not."ĬBOS noted that the lower the respondents' material standing, the higher were their security fears connected with the war.ĬBOS ran the mixed-mode survey from November 7 to 17 on a sample of 1,038 adult Poles.The aim of this study was to determine volatile compounds in red wines of Zweigelt and Rondo varieties using HS-SPME/GC-MS and to find a marker and/or a classification model for the assessment of varietal authenticity. Up to 34 percent of the pollees believe Russia will withdraw from Ukraine, while 23 percent say Ukraine will have to cede some of its territory to Moscow. ![]() A majority of Poles see the Russia-Ukraine war as a threat to Polish national security, a new poll has found.Īccording to the CBOS poll, published on Thursday, 75 percent of the respondents regard the war as a threat while 23 percent do not.Īlso, sixty-four percent of those polled believe Ukraine should continue fighting without making any concessions, whereas 24 percent say the war should be brought to an end by all means.įears for Poland's security are voiced more frequently by women (79 percent) than men (70 percent), as well as by 83 percent of elderly respondents, 79 percent of unskilled workers and 79 percent of housewives. ![]()
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