Generally speaking, the mellow taste of wine does not come from alcohol. But various trace compounds are produced in the process of brewing. If the wine contains methanol, the taste will be more exciting.
The chemical test method is: there are aldehyde groups in methanol, and the reducibility is weak. Take a certain amount of samples, put them into the mixed clear solution of ammonia, sodium hydroxide and silver nitrate, and heat them. If methanol is contained, silver ions will be reduced to form a silver mirror and attached to the test tube wall. Or heating the sample in the mixed solution of cuprous oxide and sodium hydroxide. If methanol is contained, brick red precipitate will be produced.