Anti-nutritional factors, zinc, iron and calcium in some Caribbean tuber crops and the effect of boiling or roasting

Purpose - This study aims to investigate the levels of some anti-nutritional factors and minerals and the effect of boiling or roasting on selected commonly consumed Caribbean tuber crops.Design methodology approach - Three commonly consumed tuber crops in the Caribbean namely: Yellow yam (Dioscorea cayenensis), Cocoyam (Xanthosoma sp.) and Sweet potato (Ipomea batatas) were harvested from farmers' field in the Parish of Manchester, Jamaica and assessed in their boiled, raw and roasted forms for levels of some anti-nutritional factors and minerals.Findings - Zinc and iron levels were highest in raw Yellow yam, while the highest levels of calcium were observed in Sweet potato. The phytic acid to zinc molar ratio was higher than 15 in all the tuber crops in their raw and roasted forms. Boiling reduced this ratio to below 15 for Yellow yam and Cocoyam but still remained above 15 for Sweet potato. Cyanoglucoside level was highest in raw Sweet potato followed by Yellow yam and Cocoyam. Boiling or roasting reduced the levels of cyanoglucosides. Roasting greatly lowered the level of trypsin inhibitor activity compared to boiling. The highest level of trypsin inhibitor activity was recorded in the raw tubers, and slight reductions were observed upon processing.Practical implications - Trypsin inhibitor was more stable to heat treatment compared to similar tubers grown in Africa. It may be beneficial to isolate and characterize trypsin inhibitor in these Caribbean tuber crops for utilization in nutraceutics.Originality value - This study shows that the two traditional processing methods were effective in lowering the levels of anti-nutritional factors.