Nutritional composition and bioactive components of selected indigenous fruits from the Lake Victoria Basin Districts in Uganda and Rwanda

Abstract

Indigenous fruits (IFs) play a significant role in food security, nutrition, health and income of rural households, particularly during times of famine and drought when food is scarce. This study investigated the nutritional and bioactive components of selected indigenous fruits (IFs) namely; Canarium schweinfurthii Engl. (family, Burseraceae), Vangueria apiculata K. Schum (Rubiaceae), Carissa edulis (Apocyanaceae) Garcinia buchananii Baker (Crusiaceae) and Saba comorensis Bojor (Pichon) (Apocyanaceae) in Uganda and Garcinia buchananii Baker (Crusiaceae) and Myrianthus holstii Engl. (Cecropiaceae) in Rwanda. The local uses of these IFs were assessed and ripe fruits evaluated for phenotypic and chemical characteristics: proximate and mineral composition, and bioactive components. The fruits were valued for food (consumed as snack, juice and wine) and medicine (treating 31 health conditions) with various uses varying from species to species. Cough was claimed to have been managed mostly by these IFs (Informed Consent Factor = 0.75), with G. buchananii being the most useful (Fidelity Level= 23.8%). S. comorensis registered the highest medicinal value (User Value = 0.39). The chemical properties of the fruit pulp showed that C. schweinfurthii registered the highest fat content (37.5±0.71%) and caloric value (522.70±3.53Kcal). V. apiculata had the highest content of sucrose (30.47±0.91mg/100g), dietary fibre (32.80±1.03%), ascorbic acid (687.93±8.64mg/100g), potassium (1368.25±16.26mg/100g), and antioxidant activity (2.85 IC50mg/g Ascorbic Acid Equivalent). S.comorensis had the highest contents of β-carotene (1.271±0.008mg/g) and phenolic compounds (1018.51±322.54mg/100g). M.holstii was the richest in iron (16.262±0.576 mg/100g) and zinc (2.327±0.034mg/100g). G.buchananii had the highest amounts of total flavonoids (66.50±2.09mg/100g as Rutin) while C. edulis had the highest amounts of total anthocyanins (53.92mg/100g pigment). The flavonoids identified included; apigenin, quercetin, rutin, kaempferol, myricetin and chrysoeriol. The seed oil of M.holstii (90.71%), V.apiculata (79.79%) and C.schweinfurthii (72.81%) were rich in UFA, G.buchananii in MUFA (58.12%), and V. apiculata seed oil in PUFA (78.92%). Analysis of variance showed significant variation in phenotypic and chemical composition (p≤0.05). Spearman correlation analysis showed strong correlation between total phenolic compounds and antioxidant activity (R=0.661). and Vitamin C and antioxidant activity (R=-0.968). Therefore, it is clear that indigenous fruits are rich in nutrients and bioactive components that could contribute significantly to better human nutrition and health. There is thus a need to promote the management, use and consumption of edible fruit in our communities. Development of suitable propagation techniques for IFs as well as markets for fruits and related products would promote their retention or planting on farms.