Reduction in Off-Flavors in Wine Using Special Filter Layers with Integrated Zeolites and the Effect on the Volatile Profile of Austrian Wines

Abstract

In the course of the present study, filter layers with embedded zeolites (patented layer of the company Filtrox (Zwingen, Switzerland) with the brand name Fibrafix® TX) were tested for the elimination of the wine defects, cork taint (2,4,6-trichloroanisole), mouldy aroma (geosmin), and strong “animal” phenolic aromas (4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol). The test design allowed a comparison with conventional filter layers (sterile filter layers) in a small-scale trial (25 L) as well as in a large-scale trial (125 L). By means of gas chromatography-mass spectroscopy, not only the impact compounds of the wine faults were analysed, but also the loss of volatile substances such as 15 free monoterpenes, 34 ester compounds, and 24 wood flavours. Sensory analyses were carried out by means of expert panels. The Fibrafix® TX layers were satisfactory with regard to the reduction in 2,4,6-trichloroanisole (the lead substance of cork flavour; reduction > 90%) and geosmin (the lead substance of mould flavour; reduction > 75%), but not with regard to the reduction in 4-ethylphenol, 4-ethylguaicol, and 4-ethylcatechol. However, the reduction in these off-flavours was generally not specific enough to prevent a loss of volatile compounds, especially various ester compounds and free monoterpenes. The wines obtained after filtration (in case of contamination with geosmin or TCA) were sensory faultless, but for some of the tasters, the overall quality of these wines did not correspond to the quality wine clasification.