COMPARISON OF COMPOSITION OF KOSHU WHITE WINES FERMENTED IN OAK BARRELS AND PLASTIC TANKS

Koshu musts (six-experiment series) from grapes harvested over four ye ars (1988 to 1991) were fermented at 15-degrees-C under four different conditions: (A) fermentation entirely in a small plastic tank; (B) fe rmentation entirely in a small oak barrel; (C) fermentation to about 6 % alcohol in a plastic tank followed by fermentation to dryness (about 12%) in an oak barrel; and (D) fermentation entirely in a tank, follo wed by storage in an oak barrel for the same number of days as the tan k fermentation. The production rate of ethanol and duration of complet e fermentation to dryness were slowest and longest under condition B, in spite of the fact that the fermentation temperature was slightly hi gher (about 1-degrees-C) in a barrel than in a tank. There was little difference in the production rate of ethanol, the fermentation tempera ture, and the duration of fermentation to dryness among the fermentati ons under conditions A, C, and D. There were appreciable differences i n non-flavonoid phenol, total amino acids, proline, higher alcohols, a nd esters among the wines made under the four conditions. Storage in a barrel for 13 days of the wines fermented completely in a tank increa sed the non-flavonoid phenols, but did not influence the composition o f higher alcohols and esters. The results suggest that the difference in the composition of proline, higher alcohols, and esters was due to the degree of turbidity (suspended materials) of the fermenting must a nd the extent of aeration, which differed with the containers used.