Comparative mineral composition among canola cultivars and other cruciferous leafy greens

The potential of canola (Brassica napus L.) leafy greens as a food source for human consumption is being considered to increase the variety of nutritious vegetables available to consumers. Scientific evidence supports that the consumption of cruciferous vegetables may reduce individual risk factors for some diseases. Five canola cultivars were grown at Alabama A & M University, Winfred Thomas Agricultural Research Station, in Hazel Green, AL, USA, and were analyzed to determine mineral composition of raw canola leafy greens for comparison to those of collard greens (Brassica oleraceae var. viridis), kale (Brassica oleraceae L. acephala) and cabbage (Brassica oleraceae L. var. capitata). Results showed that collard greens were significantly higher in potassium (K) than the other crops tested; however, canola was significantly higher in K than cabbage and kale. The essential micronutrient, iron (Fe), (24.77 mg/100 g dry weight), was significantly higher in canola and lowest in cabbage (7.65 mg/100 g dry weight). Zinc (Zn) and manganese (Mn) contents of canola (3.00 and 16.40 g/100 g dry weight, respectively) were greater than cabbage and collard. Among the three canola harvest stages (rosette, budding and blooming), K content increased with growth, while Fe and aluminum (Al) decreased; sodium (Na) was lowest at the budding stage compared to the other two stages. The results of this research indicate that canola greens can be an acceptable substitute for traditional leafy green vegetables.