Why do grape-based fruit wines could be “super” magic?

In Europe, the global consumption of wine is decreasing and new alternatives of wine have been appearing on the market. The attractiveness of these products rely on the fact that they are inexpensive and easy to drink, with low alcohol content and obtained by mixing wines with fruit juices or flavoring wine. While fruit wines represent an ancient art [1], no studies have investigated the production of beverages that are obtained by the co-fermentation of grape and fruit. The formulation of new mixed-fruit wines could represent the basis for reducing post-harvest fruit losses and contribute to the economy of the existing wine industry. Moreover, throughout the selection of useful yeasts that drive the alcoholic fermentation, the final products could be enriched in novel active bio-functional compounds not found in traditional wines. The research activity has involved the setup of fermentation trials using grape must and fruit juices of strawberry, peach, cherry and kiwi. Must fermentations were carried out inoculating Saccharomyces cerevisiae and Torulaspora delbruekii species in four musts obtained by blending grape must (Chardonnay and Cabernet Sauvignon) and juices at 80:20 and 60:40 grape:fruit juice proportion. The aromatic profile was determined by GC-MS. S. cerevisiae was able to exhaust the available sugars in all trials. In particular, based on the proportion used, alcohol was 3-5% less in wines prepared with red grape and 6-7% (v/v) less in case of white grape. T. delbruekii showed a good fermentation performance as well, suggesting its potential use as starter yeast. Only negligible difference was found for the pH, while the total acidity was higher for mixed-fruit wines obtained with must from white grape and at the 60:40 proportion. In particular, the high level of citric acid detected (up to 8 g/L) in some products could exert a beneficial effect by protecting the wine components, bio-functional compounds included, against oxidation.