I wonder if the fact that the raisins have been so exposed to air as they dried that the oxidized fruit carries a sherry flavor.I've made a couple 1 gallon batches of golden raisin wine from Terry Garey The Joy of Home Winemaking. I liked them and just used ec1118 yeast. I blended the raisins after an overnight soak and put them in a mesh bag for fermentation. I find that it has a sherry-like quality. Cheers.