Plant Fibers in Comparison with Other Fining Agents for the Reduction of Pesticide Residues and the Effect on the Volatile Profile of Austrian White and Red Wines  
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[PERSON]. few, were already well documented in the early 2000s. More recently, studies on residues in wines with different subjects have also been published [13; 14; 15; 16; 17; 18; 19]. Ref [20] summarized in a review the reported levels of residues found in wine grapes, must, and wine in recent years and discussed the impact of these residues on wine quality, in particular on alcoholic fermentation. Simplified, all these studies clearly show that individual pesticide residues of different groups can be detected in sometimes high concentrations (in some cases far above 0.1 mg/L) and that both wine quality and fermentation dynamics of wines can be affected by them. However, many authors [5; 21; 22; 23; 24] have shown that when pesticides are used correctly, and the mandatory waiting periods are respected, the levels of pesticide residues do not exceed the legal maximum concentrations (Maximum Residues Limits (MRL's)) for wine grapes. No specific limits for wine have been defined in Austria so far [5], but the concentrations of residues gradually decrease during destemming, pressing, must fining, alcoholic fermentation, wine treatment, filtration and storage [24]. However, since these natural reductions of pesticides are often not enough, some authors [24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35] conducted experiments with different fining agents to investigate their reducing capacity. In summary, these studies have shown that different fining agents can be used to reduce a variety of undesirable compounds. Results using activated carbon to reduce 13 different fungicides (boscalid, cyprodinil, fluidoxonil, fenhexamid, pyrimethanil, cyazofamid, dimethomorph, fluopicolide, iprovalcirarb, metrafenone, penconazole, spiroamine, and trifoxystrobin) in grape must showed an average reduction of 30% in must contents [41]. Ref [25; 26; 28; 37; 38] also showed a significant reduction when activated carbon was used in must or wine. Ref [46] concluded that fining with bentonite promoted the elimination of about 93% of cyprodinil and 73% of famoxadone, while other pesticides were not significantly reduced by bentonite [38]. Ref [44] showed that 17.3% of the studied pesticides were reduced by the use of polyvinylpolypyrilidone (PVPP). Ref [39] documented the reduction of fungicides by activated carbon and PVPP. Other fining agents have also been studied for their effectiveness at reducing various substances from wines [44; 45]. For example, egg albumin significantly reduced the levels of pyrethroids (>50%) and procymidone (about 30%), while casein showed a 35% reduction in the concentration of hexaconazole in wines. In addition, it is reported that a combined fining agent consisting of bentonite, PVPP, potassium caseinate, and diatomaceous earth was more effective than isolated bentonite in reducing concentrations of boscalid in wine [20]. All these studies focus exclusively on the reduction of pesticides but do not really investigate the effect of fining on wine quality and, in particular, on the aroma profiles of the wines. Only [47] studied the combined effect of small amounts of activated charcoal in must on the reduction of pesticides and volatile compounds. The treatment with different activated charcoal significantly reduced the levels of fungicides while the aroma of the wines was not significantly affected. However, this study was limited to some higher alcohols, C6 alcohols, carboxylic acids, and few ester compounds. A general principle of winemaking asserts that any treatment should only be carried out if it is actually necessary and that using treatments in larger quantities does not automatically lead to better wine quality [48]. Following these guiding principles, wine researchers and, in particular, manufacturers of wine treatment agents, are permanently searching for new products to subtly improve the quality of the wines.