Assessment of Nitrate Content in Lettuce Marketed in Serbia: Influence of Cultivation Method, Season, and Production System

Abstract Intensive agricultural production and the excessive use of nitrogen fertilizers have led to increased nitrate accumulation in vegetables, particularly leafy greens, which may exert negative effects on human health. The objective of this study was to assess the nitrate content in lettuce marketed in Serbia, considering the influence of cultivation method, season, and production system. A total of 20 lettuce samples were collected from various sources (including supermarkets, independent shops, and farmers’ markets), cultivated either in greenhouses or open fields during winter and spring. Nitrate content was determined using the steam distillation method after a 30-minute extraction in hot 1 M NaCl solution. The results were statistically analyzed using the one-way ANOVA, followed by the Tukey HSD test.The results showed that none of the samples exceeded the maximum permissible nitrate concentrations according to the current regulations. The nitrate content ranged from 28 to 663 mg/kg. No statistically significant differences were found between the greenhouse and open-field lettuce or between the winter and spring samples. However, the organically grown lettuce exhibited significantly lower nitrate levels compared to the conventionally produced lettuce.It was concluded that the lettuce marketed in Serbia complies with the food safety standards regarding nitrate content. Nevertheless, variations in nitrate concentration indicate the need for continuous monitoring.