Nutritional content and antioxidant properties of edible indigenous wild fruits from miombo woodlands in Tanzania

Abstract

Edible fruits of four indigenous plants (Uapaca kirkiana, Strychnos cocculoides, Syzygium guineense and Ximenia caffra) from miombo woodlands of Ruvuma Region in Tanzania were evaluated for nutritional composition and antioxidant properties. Fruits from the four plants were collected for extraction of the edible portion that was subsequently subjected to laboratory analysis using standard procedures. Soluble carbohydrates dominated among macronutrients evaluated (16.326 to 56.001%) and potassium was the most abundant mineral nutrient among those studied with the concentration ranging from 429.4 to 671.73 mg/100 g. The total phenolic contents, flavonoids and vitamin C in X. caffra were 1915.88 mg GAE/100 g, 178.46 mg RE /100 g and 359.90 mg/100 g respectively which are significantly higher than those in other species studied. Similarly, X. caffra showed significantly higher free radical scavenging activity with lower EC₅₀ (effective concentration for free radical reduction by 50%) achieved at 0.08 μg/ml than other fruit species studied. A strong positive correlation was observed between free radical scavenging activities with vitamin C (r = 0.973), total phenolics (r = 0.866) and flavonoids (r = 0.858). These observations imply that indigenous fruits studied could be used as valuable sources of nutrients and vital natural antioxidant to human diets.

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Keywords: Macronutrients, minerals, phenolics, flavanoids, vitamin C, Free radical scavenging