Progressive Freeze-concentration of 'Ruby Roman' Grape (Vitis Labruscana Bailey) Juice and its Application to Wine Production

'Ruby Roman' grape (Vitis Labruscana Bailey) juice was concentrated from 14.6 to 23.0 Brix by progressive freeze-concentration (PFC) with a closed circulation flow system. The distribution of organic acids and flavors was measured, and no substantial changes were observed in the component profiles before and after PFC concentration. The PFC-concentrated 'Ruby Roman' grape juice was fermented to produce Ruby Roman wine, in which the obtained ethanol concentration was as high as 14.5 vol%. Thus, a sufficient alcohol level can be obtained without chaptalisation by using PFC concentration. Following fermentation, acetic and succinic acids increased in the organic acid distribution. In the flavor distribution, some components in the original juice disappeared, while fermentation products such as ethanol, isoamyl acetate, isoamyl alcohol, ethyl octanoate, phenethyl alcohol, octanoic acid, and decanoic acid newly appeared. Overall, the Ruby Roman wine retained sufficient amounts of flavors from the original juice. The present results suggest the possibility of producing a new-type of Ruby Roman wine, not presently available on the market.