Influence of several fungicides on the antioxidant activity of red wines (var. Monastrell)

Influence of fungicide residues and in vitro gastrointestinal digestion on total antioxidant capacity and phenolic fraction of Graciano and Tempranillo red wines

The effect of fenhexamid, mepanipyrim and cyazofamid fungicides on in vitro bioavailability of antioxidant activity and phenolic compounds of Tempranillo and Graciano red wine was studied by simulating the digestive process by dialysis in semipermeable membranes. Determination of antioxidant activity was through reaction with the DPPH • radical and the measurement of phenolic compounds was made with liquid chromatography with diode detector (HPLC-DAD). Fenhexamid, mepanipyrim and cyazofamid reduce the total polyphenol content in both wines. During dialysis there was a large loss of total polyphenols (80-90%) and of antioxidant activity (> 90%). The bioavailability of the phenolic compounds is lower than that for non-treated wines and the highest dialization percentages were found for stilbenes > 50%. While for the remaining phenolic fraction the order is the following hydroxycinnamic derivatives > anthocyanins > flavonols.

Determination of fungicide pyrimethanil in grapes, must, fermenting must and wine

BACKGROUND

This study determined the evolution of pyrimethanil, a fungicide commonly used to control Botrytis cinerea, throughout the winemaking process in grapes, must, fermenting must and wine. Tempranillo grapevines were treated with pyrimethanil according to both good Agricultural Practices (GAP) and Critical Agricultural Practices (CAP). Fermentation was carried out in an experimental winery. Grape analysis was based on an ethyl acetate extraction method. Samples from fermentation were analysed by solid phase extraction. The determination was carried out by gas chromatography with nitrogen-phosphorus detection (GC-NPD) and additionally confirmed by gas chromatography/mass spectrometry (GC/MS).

RESULTS

Pyrimethanil residues were at least ten times greater in grapes treated 7 days before harvest than in those treated respecting the safety period (21 days). The amount of pyrimethanil in grapes treated under GAP was below the maximum residue limit (5 mg kg(-1)). The level of pyrimethanil decreased during fermentation in both treatments. In the fermentation of grapes treated according to CAP, the pyrimethanil concentration was reduced by over 50% on the first day and then remained constant until the end of the fermentation process. For grapes treated in compliance with GAP, the amount of pyrimethanil decreased to a level below the limit of detection in the bottled wine.

CONCLUSION

The described methods for grapes, must, fermenting must and wine gave good recoveries, linearity, precision and accuracy. They were also highly sensitive in avoiding matrix effects. Pyrimethanil residues found in treated grapes were higher in skin than in pulp. The amount of pyrimethanil decreased during fermentation by degradation and/or adsorption. For grapes treated according to GAP, residues disappeared in the final bottled wine. The decrease observed in the final bottled wine may be caused by diverse oenological practices and technologies such us malolactic fermentation, racking and settling.

Chromatographic determination of fungicides in biological and environmental matrices. New achievements

The newest results in the chromatographic analysis of synthetic and natural fungicides present in biological and environmental matrices are collected and critically evaluated. Examples of the employment of gas chromatography, liquid chromatographic technologies, such as thin-layer chromatography and high-performance liquid chromatographic methods as well as electrically driven systems are presented. The advantages and disasdvantages of the various chromatographic technologies are briefly discussed and the efficacies of the methodologies are compared.

Characterization of phenolic content, in vitro biological activity, and pesticide loads of extracts from white grape skins from organic and conventional cultivars

Grape skin extracts of Riesling Vitis vinifera L. grapes from conventionally or organically managed cultivars were compared on the basis of their phenolic content, antioxidant capacity, antimicrobial and antimutagenic properties and pesticide loads. Promising results on their biological properties suggest that those extracts would be valuable as food preservatives. The antioxidant capacity of conventional extracts was significantly higher, according to the higher content in catechin, epicatechin and procyanidin B. Pesticide loads did not affect the antimutagenic or antimicrobial properties of the extracts. Both extracts inhibited the growth of Gram-positive foodborne pathogens such as Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium to similar extents. Possibly as a result of higher amounts of quercetin and its derivatives, higher antimicrobial effects against Listeria monocytogenes and Salmonella typhimurium were observed for the organic white grape skin extracts. Conventional or organic extracts did not show remarkable antimutagenic effects when tested against the mutagen IQ by means of the Ames test. Due to the presence of fungicides, the conidial germination of Penicillium expansum, Penicillium chrysogenum and Aspergillus niger, were inhibited by 95% by conventional GSE, while negligible effects were observed with organic grape extracts. The latter, however, showed inhibitory effects against Trichoderma viridie and Aspergillus versicolor.