Lowering polyphenol concentrations in press juice so that the treated juice can be used for preparation of products other than distilling wine
Rebate wines were prepared over two harvests from free run juice, as well as juice from different press levels (1,5 bar, 2 bar and above 2 bar). The juices were subjected to phenol removing treatments before fermentation, e.g. flotation, hyper-oxidation and fining with gelatine and bentonite. Other treatments included settling with pectolytic enzyme after treatment with gelatine and the addition of sulphur dioxide. Controls were also prepared from the free run and press juices.
The rebate wines and brandies prepared from press juice were of acceptable quality and did not differ significantly from the free run controls. The juice obtained from the high (2 bar) and extra high (more than 2 bar) treatments were not significantly poorer in quality than the free run fraction. It seems that phenol removing treatments do not improve the quality of the products made form the press juice. The clarity of the juice has a positive influence on the quality of the products. The results were similar for both the 1997 and 1998 harvests.
Because of the excess white wine on the market and the resulting low prices of the wine, it is now less important to establish how high pressure press juice of white wine can be utilised. It is therefore decided to discontinue the rest of the project, but to complete the study on rebate wine.