Beta-carotene is one of phytochemicals which play role as natural antioxidant related to the reduction of oxidative stress that is linked to Non-communicable diseases (NCDs). Sweet leaf (Sauropus androgynous), one of the indigineous plants in Asia, contains high contents of beta-carotene. However, the bioaccessibility of beta-carotene in sweet leaf might be altered among the different cooking methods. Therefore, the effects of different cooking methods (raw, boiling, and microwave cooking) and addition of palm oil on the bioaccessibility of beta-carotene of sweet leaf were investigated before and during in vitro simulated gastrointestinal digestion. We found that the boiling and microwave cooking methods caused the lower beta-carotene contents in cooked sweet leaf compared to raw leaf. However, the addition of 10% (v/w) palm oil during cooking helped increasing the bioaccessible beta-carotene contents after digestion in all cooking methods, compared to those without palm oil addition (p<0.05). In addition, the bioaccessibility of beta-carotenes was found to increase about 20% when the palm oil was added into the microwaved sweet leaf. The findings of this study suggested that the addition of 10% (v/w) palm oil during cooking could improve the bioaccessible beta-carotene contents in the sweet leaf, especially when the sweet leaf was cooked by microwave.
Keywords: Beta-carotene; Sauropus androgynous; bioaccessibility; cooking methods; palm oil.