Crossover starter yeast strains for the production of Italian Grape Ale (IGA), a fruit beer brewed after grape must adding.

A new beer type known as Italian Grape Ale (IGA), a kind of link beverage between wine and beer nowadays represents a popular and trendy production choice among brewers in Italy. In this investigation, three autochthonous Saccharomyces cerevisiae strains (denoted CHE-3, P4, TA4-10), formerly isolated from different food niches, were evaluated for brewing in comparison with the commercial strain US-05. Fermentations were carried out at a laboratory scale on malt extract added with 15% or 25% grape must and on malt wort alone (control). During fermentation, CHE-3, P4, TA4-10 strains produced CO2 amounts significantly higher than US-05. The adding of the grape must improved the CO2 production, particularly when the wort was supplement with 25% of grape must. Both the grape must addition to the fermentation medium and the used strains intensely influenced several analytical parameters such as the profile of volatile compounds, they being related to the organoleptic quality of the produced beers. The highest aromatic was detected in the IGA with 15% grape must addition. To the best of our knowledge, this investigation is the first one concerning the employment of the microbial cross-over for the production of IGA craft beer in Southern Italy. The results obtained showed that both the yeast strain and the fermentation substrate determined the process dynamics and physico-chemical features of IGA beers. We showed that yeast starter strains originating from other traditional food chains could brew high quality IGA beer, thus endorsing the potential of cross-over fermentation for the development of novel beverages. Moreover, these findings confirm that wild microorganisms, isolated from diverse niches and preserved in microbial collections, are a fundamental pool of novel starter cultures able to produce enhance foods and beverages differentiation.