NITRATE AND VITAMIN C CONTENT IN RADISH (RAPHANUS SATIVUS) FROM DIFFERENT PRODUCERS: INFLUENCE OF VARIETY, SOURCE, AND SEASONALITY

The aim of the study was to analyze the content of nitrates and vitamin C in radish (Raphanus sativus) from different producers and to evaluate the influence of variety, origin, and seasonality on these parameters. The red and white varieties of radish were purchased regularly each month over a 12-month period from the same two producers at a local marketplace and from a retail chain. The conventional Tillmans titration method was used to determine vitamin C content, while nitrate levels were measured using the direct potentiometric method with a nitrate ion-selective electrode (ISE). The results of the annual analyses monitoring nitrate content in the red and white varieties of radish from different producers showed that the average nitrate concentration was higher in the red variety, reaching 1308 mg/kg, while the white variety contained 1246 mg/kg. Regarding the origin, the highest nitrate content was found in red radishes purchased from the retail chain (1463 mg/kg). During the spring months, higher nitrate levels were detected in both radish varieties, though in the red variety, the difference was not statistically significant (p>0.05). Over the annual monitoring period, the red variety contained more vitamin C (18.5 mg/100g) compared to the white variety (14.6 mg/100g). Radishes sold in the retail chain had slightly higher vitamin C content (18.9 mg/100g) compared to those from the marketplace vendors. Additionally, it was confirmed that the summer months represent a significantly (p<0.05) greater source of vitamin C compared to the winter and autumn periods.