Effects of agriculture production systems on nitrate and nitrite accumulation on baby-leaf salads

Authors

  • Alfredo Aires,

    Corresponding author
    • CITAB-Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro, 5001-801 Vila Real, Portugal
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  • Rosa Carvalho,

    1. Agronomy Department, University of Trás-os-Montes and Alto Douro, 5001-801 Vila Real, Portugal
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  • Eduardo A. S. Rosa,

    1. Agronomy Department, University of Trás-os-Montes and Alto Douro, 5001-801 Vila Real, Portugal
    2. CECAV-Veterinary and Animal Science Research Center, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
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  • Maria J. Saavedra

    1. CECAV-Veterinary and Animal Science Research Center, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
    2. Veterinary Science Department, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
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Correspondence

Alfredo Aires, CITAB-Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro, P.O. Box 1013, 5001-801 Vila Real, Portugal. Tel: +351 259350435; Fax: +351 259350327; E-mail: alfredoa@utad.pt

Abstract

Nitrate and nitrite are widespread contaminants of vegetables, fruits, and waters. The levels of these compounds are increased as a result of using organic wastes from chemical industries, domestic wastes, effluents, nitrogenous fertilizers, and herbicides in agriculture. Therefore, determining the nitrate and nitrite levels in biological, food, and environmental samples is important to protect human health and the environment. In this context, we set this study, in which we report the effect of production system (conventional and organic) on the accumulation of nitrates and nitrites in fresh baby-leaf samples. The average levels of the nitrate (NO3) and nitrite (NO2) contents in six different baby-leaf salads of a single species (green lettuce, red lettuce, watercress, rucola, chard, and corn salad) produced in organic and conventional agriculture system were evaluated. Spectrophotometric analytical method recently published was validated and used. Nitrates and nitrites were detected in all samples. The nitrates levels from organic production varied between 1.45 and 6.40 mg/kg fresh weight (FW), whereas those from conventional production ranged from 10.5 to 45.19 mg/kg FW. The nitrites content was lower than nitrates and ranged from 0.32 to 1.89 mg/kg FW in organic production system and between 0.14 and 1.41 mg/kg FW in conventional production system. Our results showed that the nitrate content was dependent on the agricultural production system, while for nitrites, this dependency was less pronounced.

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