The study has been performed to analyze the content of nitrates V and III as well as lead and cadmium in Brassica vegetables, both fresh and after 5-month storage in a cool storeroom. The experimental material consisted of Chinese cabbage, red and white cabbage, savoy cabbage and Brussels sprouts. The content of nitrates in the plant material was determined with the spectrophotometric method based on Griess reaction, whereas concentrations of heavy metals were assayed with the AAS method after dry mineralization. The 5-month storage period was found to decrease (by ca 65±5%) the content of nitrates V in savoy cabbage and Brussels sprouts. In turn, a ca 2-fold increase in the concentration of these compounds was determined in Chinese cabbage, and a similar tendency was observed in white cabbage. Chinese cabbage turned out to be the richest in the analyzed, undesirable elements and compounds, e.g. after storage it was characterized by an exceeded permissible level of nitrates V (750 mg kg–1 f.w.) and by the biggest, ca 10-fold, increase in concentrations of lead and cadmium. Besides, storage was observed to cause a significant increase in the content of nitrates III in the analyzed vegetables, except red cabbage, in which their content was shown to decrease by about 40%. Concentrations of nitrates III and V, Pb2+ and Cd2+ in tissues of the cabbage plants should be monitored regularly in order to prevent their excessive accumulation in the food chain of man.

17.2.2012