###### 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(r) 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-ethylguaiocal, 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 monoterpenses, 34 ester compounds, and 24 wood flavours. Sensory analyses were carried out by means of expert panels. The Fibrafix(r) 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-ethylguaiocal, 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 monoterpenses. The wines obtained after filtration (in case of contamination with geosmin or TCA) were sensory faultless, but for some of theasters, the overall quality of these wines did not correspond to the quality wine classification. wine faults; depth filtration; volatile compounds; GC-MS; geosmin; TCA; 4-ethylphenol; esters; free monoterpenses +
Footnote †: journal: Accepted: 23 April 2022  
with other mould aromas [5; 6; 7]. A new paper summarised a number of possibilities for the reduction in already existing mould aromas in wine and tested in a practice trial the depth filtration using filter sheets with embedded zeolites. In the process, an approximately 85% reduction in geosmin could be achieved [8]. The use of such filter layers with zeolite Y faujasites was already approved by resolution OIV-OENO 444-2016 in 2016 [9]; the principle behind this technique is a molecular sieve and zeolite Y faujasites synthesised minerals for flexible and stable design [10]. The patent-pending depth filter sheet FIBRAFIX(r) TX-R and has been developed by the company Filtrox group (Zwingen, Switzerland) for the adsorption of haloanisoles. The effectiveness of the product Fibrafix TX-R in the removal of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole from wine has been clarified for some time [11; 12], but recent results show that, in addition to the findings regarding the activated carbon, which is damaging to the wine quality [13; 14], these layers are also a good alternative for the reduction in mould aromas [8; 15]. Some unconfirmed practical reports even attest to a certain reduction power of these layers against the leading substances of the wine defect \"animal\" phenolic character. The authors are not aware of any experiments in this regard. Even though the nasal and retronasal perception of wine faults is very complex and, above all, depends essentially on the aroma buffer of the wines [16], sensory threshold values can help assess the effectiveness of methods for reducing wine faults. The determination of sensory and olfactory thresholds is not a trivial task from many points of view, as they depend on very many partly subjective parameters. Accordingly, there is a respective range of threshold values in the current literature. The range of threshold values for mould aroma (impact substance: geosmin) [17] in the literature is 17.0 to 90.0 ng geosmin/L [17; 18; 19].