Phenolic assessment of white musts: Varietal differences in free-run juices and pressings

Authors

  • T. C. Somers
  • K. F. Pocock

DOI:

https://doi.org/10.5073/vitis.1991.30.189-201

Keywords:

white variety of vine, must, wine, flavonoid, polyphenol, analysis, berry skin, temperature, press, draining, fining

Abstract

Direct spectrophotometry over the range 250-400 nm enables rapid assessment of juice fractions from commercial juice preparation systems. Attention is focused on spectral estimates of the total flavonoids which increase during skin contact, with increasing must temperature, and particularly during recovery of heavy pressings.
Spectral data from many sets of commercial juice fractions, concerning eight grape varieties in several districts, were collated over three seasons, 1987-88-89. Such observations have indicated the prime importance of grape variety in relation to phenolic extract in the juice fractions. The data have suggested the notion of 'spectral recognition profiles' arising from intrinsic varietal differences in the distribution of phenolic constituents within wine grapes.
Thus the flavonoid concentration appears to be a significant variable of varietal dry white wine style. Qualitative differences in phenolic composition have also been demonstrated by differential spectrophotometry of model skin extracts at 250-300 nm.
Fining treatments with various commercial fining agents had only minor effect on flavonoid levels in juice pressings and in press wines.

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Published

2015-10-22

Issue

Vol. 30 No. 3 (1991): Vitis

Section

Article

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