Influência das condições fitossanitárias da uva no teor de ocratoxina A em vinhos brancos

Abstract

The ochratoxin A (OTA) is a mycotoxin with nephrotoxic, nephrocarcinogenic, teratogenic and immunossupresive properties that can be found in grape juice and wine, as well as other food groups, like cereals and oil seeds. Its occurrence in grapes and afterwards in musts and wines is due mainly to the phytosanitary conditions of grapes, besides their variety, the degree of berry maturity, physical damage, viticulture practices and climatic conditions; once the ochratoxin A is produced by strains of Penicillium and Aspergillus species. The objective of this study was to determine the relationship between the phytosanitary conditions of grape and the level of ochratoxin A in white vitis vinifera musts and wines. The grapes were collected at Cooperativa Vinícola Aurora Ltda., localized in Pinto Bandeira, a district of Bento Gonçalves, RS from three varieties of white vitis vinifera (Gewürztraminer, Chardonnay and Sauvignon Blanc). The grapes were collected four (4)days apart from the harvest day stablished by the vineyard (day zero) up to the eighth (8) (to Gewürztraminer and Sauvignon Blanc wines) and fifteenth (15) days (Chardonnay). The maturation criteria were the º Brix and total acidity determinations. The collected amount of grape in each sample was approximately 6 Kg and three repetitions of each sampling (to each grape variety), were made. The plant s selection was randomized, by the collection of a small amount of bunches in each sample. The grape microvinification was made after the harvest. In the musts was realized the determination of pH, soluble solids (º Brix) and total acidity. In all the wine samples these physic-chemical parameters were analyzed: alcohol content, density, pH, total acidity, volatile acidity; total sugar and reduced dry stratum. The determination of ochartoxin A in musts and wines was done by High-Performance Liquid Chromatography (HPLC) with fluorescence detection accordingly to the of Office International de La Vigne et Du Vin (OIV) (2001), with the use of immunoaffinity columns. Statistical analysis was performed using the program SAS for Windows 2000, version 6.11. Even presenting different conditions of sanity, neither the musts nor the wines had detectable levels of ochratoxin A. The physic-chemical analysis was in the range accepted by the legislation of wines production for beverage.