Carotenoids content of Corchorus olitorius and Solanum macrocarpon - commonly used Ghanaian vegetables

Green leafy vegetables are rich in carotenoids. The study investigated the effect of duration of storage and cooking time on the carotenoids in Corchorus olitorius and Solanum macrocarpon, locally known as ‘adeimey’ and ‘gboma’ respectively. The storage conditions were: overnight at room temperature (25°C), refrigeration for one day and a week, and cooking at 100oC for thirty minutes. The three individual carotenoids and total carotenoid content (TCC) were quantified using HPLC and by measuring absorbance at 450 nm, respectively. The TCC varied from 17.1 mg/100 g to 670.2 mg/100 g. The β-carotene content ranged from 7.5 mg/100 g to 196.3 mg/100 g while lutein ranged from 1.4 mg/100 g to 112.8 mg/100 g. The zeaxanthin content ranged from 0.7 mg/100 g to 16.3 mg/100 g. These results show that the two green leafy vegetables are good sources of carotenoids. There were variations in the concentrations of carotenoids in Solanum macrocarpon and Corchorus olitorius with the latter having a higher carotenoids content than the former. β-carotene was the most predominant carotenoid whilst zeaxanthin was the lowest in the vegetables studied. It was observed that the β-carotene, lutein, zeaxanthin and the total carotenoid contents decreased drastically when the vegetables were left to stand overnight at room temperature, refrigerated for one day and a week and then cooked for thirty minutes. These findings suggest modification in the storage and cooking practices of these green leafy vegetables to ensure retention of the carotenoids for the best nutritional value and health benefit; hence the need for policy towards nutrition education on vegetable processing and storage.