Mineral composition and the content of phenolic compounds of ten broccoli cultivars

Our objective was to determine the content of macro- and micronutrients, toxic heavy metals as well as total phenols in 10 broccoli (Brassica oleracea var. italica) cultivars. The experiment was designed at the Poznań University of Life Sciences, Poland, and completed during two plant growing seasons. Broccoli seedlings were planted in a field in early July and the plants were harvested between September and October. The content of general forms of nitrogen was measured by distillation with the Kjeldahl method. The content of potassium, calcium and sodium was assessed by flame photometry, and the content of magnesium, cadmium, lead, nickel, copper, zinc, manganese and iron was determined by flame atomic absorption spectroscopy (FAAS). The content of heavy metals, macronutrients and sodium in the broccoli heads depended on a cultivar. Having analyzed the levels of macronutrients in ten broccoli cultivars, it was concluded that cv. Agassi and Tradition had the highest content of nitrogen and phosphorus. A very high amount of phosphorus was also found in cv. Beaumont. The highest concentrations of calcium and potassium were found in cv. Monte Carlo. The cultivars Agassi, Beaumont, Tiburon and Tradition were characterized by the highest content of magnesium. The highest content of sodium occurred in the cultivars Beaumont and Monopoly. With respect to micronutrients, the highest content of iron, copper, zinc and manganese was revealed in cv. Agassi. The highest content of nickel was determined in the cultivars Beaumont and Monte Carlo. In addition, the cultivar Monte Carlo was characterized by the highest content of lead, and Beaumont had the highest content of cadmium. However, the maximum permissible levels of cadmium and lead were not exceeded in the heads of the ten broccoli cultivars. In both years of the study, the highest content of phenols was found in cv. Steel and the lowest one appeared in cv. Agassi.