In vitro accessibility of carotenes from green leafy vegetables cooked with sunflower oil or red palm oil

Abstract

Although vegetables and fruits are readily available and consumed in most areas of Tanzania, vitamin A deficiency is still prevalent. The objective of the present study was to measure the in vitro accessibility (available for absorption) of _α-carotene and _β-carotene in vegetable relishes prepared with or without oil. Derived results were used to calculate the contribution of vegetable relish to recommended daily intake of retinol. Five sundried green leafy vegetables from Tanzania were cooked without oil, with sunflower oil or with red palm oil. The total amount and in vitro accessibility of _α-carotene and _β-carotene from a portion (100 g) of vegetable relish was determined. The in vitro method used simulated the digestion process in the gastrointestinal tract. Carotenoids released after digestion were quantified using high-performance liquid chromatography. The total amount of _β-carotene varied between 1211 and 3659 μ g/100 g among the five vegetable sources studied. From green leaves cooked without oil, 8-29% of the _β-carotene content became accessible after in vitro digestion and 39-94% from leaves cooked with sunflower oil or red palm oil. Adding red palm oil instead of sunflower oil resulted in about twice as much accessible _β-carotene, due to the high accessibility of its _β-carotene content. The red palm oil contributed also a considerable amount of _α-carotene. The results showed that by eating vegetable relishes with added oil daily, it should be possible to provide the recommended intake level of vitamin A.