Genetically engineered East African highland bananas – proximate analysis and effect of cooking on the enhanced provitamin A levels

Abstract

Micronutrient deficiency is a major challenge in the developing world. This is mainly attributed to over-reliance on starchy staples foods such as cassava, rice and banana among others, which are deficient in micronutrients such as vitamin A and iron. Strategies put in place to provide a solution to micronutrient deficiencies such as dietary supplementation of vitamin A and food fortification have not been successful in the developing world due to high costs and unreliable supply chains (food and medical). Biofortification of the easily accessible staple foods could help reduce this problem associated with micronutrient deficiency. On this account, the Biofortification project in Uganda under the National Banana Program developed transgenic East African Highland Bananas (EAHBs) (M9 and Nakitembe) with enhanced levels of provitamin A (PVA) using the Fe’i banana-derived phytoene synthase 2a (MtPsy2a) gene. To determine the nutritional quality of the transgenic bananas, an analysis of the proximate composition of the biofortified East African Highland Bananas was carried out. The effect of cooking on retention of provitamin A carotenoids (pVAC), was assessed using two cooking methods; boiling and steaming (most common methods of preparing cooking banana meals in Uganda). It was observed that there were no significant (P≤0.05) differences in moisture content (P=0.4287), carbohydrate (P=0.3966), crude fat (P=0.4051), crude fiber (P=0.3214), protein (P=0.0858) and ash content P=0.1336) between transgenic and non-transformed bananas. It was found that steaming, as a cooking method allowed for retention of more provitamin A carotenoids compared to boiling. Comparison of the cultivars on their retention of provitamin A carotenoids, results indicated that Nakitembe was superior to M9. Genetic engineering of bananas by biofortification has no effect on major food components in EAHBs (M9 and Nakitembe) and, therefore, genetically modified M9 and Nakitembe are substantially equivalent to the non-transgenic controls and the biofortified bananas can provide the necessary nutrients even after cooking. This data will inform subsequent steps for the commercialization of biofortified EAHBs.