Efficacy of clarifying agents in the removal of pesticide residues in red wine


By Karien O'Kennedy

The aim of the study was to evaluate different clarifying agents for their efficacy to remove pesticide residues from red wine. Residues have been detected in both white and red wines due to pesticide use in viticulture for crop protection.

Experimental layout:

  • Certified reference standards of 23 pesticides were obtained and two mixtures prepared, one containing all 23 pesticides and one only nine pesticides, representing nine main chemical groups. 
  • 75 ml samples of red wine (Greek cultivar: Agiorgitiko) were treated with the pesticide mixtures as well as with single solutions of the different pesticides. 
  • Seven fining agents were used for the trial: food grade activated carbon, bentonite, PVPP, gelatin, egg white, isinglass and casein. With the exception of the activated carbon all fining agents were obtained from Laffort.
  • Two different dosages of each fining agent were used, the minimum and maximum dosages as suggested for winemaking. 
  • Pesticide residues were determined after fining using SPE and GC-ECD.

Results:  

  • All seven fining agents were used in the 23 pesticide mixture samples. The order of removal of pesticides was as follows: activated carbon (10 g/hl) 40% ﹥ gelatin (10 g/hl) 23% ﹥ egg white (10 g/hl) 21% ﹥ PVPP (20 g/hl) 18%﹥ casein (20 g/hl) 12%﹥ bentonite (25 g/hl) 7%. Isinglass removed 12% of pesticides at but was used at a much lower dosage than the other fining agents (3 g/hl). 
  • In the nine pesticide mixture samples three clarifying agents were tested. The order of removal was: activated carbon 52% ﹥ egg white 32% ﹥ PVPP 26%.
  • In the case of the single pesticide mixtures only two clarifying agents were used: activated carbon and egg white of which activated carbon generally was the most effective in removal. 
  • When comparing red wine pesticide removal with similar experiments on white wine activated carbon, isinglass and casein was less effective on red than on white at the same dosage. 

Significance of the study:

The use of pesticides is still widespread in viticulture. In order to control final concentrations in wines it is useful to know which fining agents work the best.

Reference:

Effect of clarification process on the removal of pesticide residues in red wine and comparison with white wine
Danae S. Doulia, Efstathios K. Anagnos, Konstantinos S. Liapis & Demetrios A. Klimentzos
Pages 534-545 | Received 13 Nov 2017, Accepted 20 Mar 2018, Published online: 30 Apr 2018
https://doi.org/10.1080/03601234.2018.1462937

Image: Shutterstock

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