Phenolics, organic acids and minerals in the fruit juice of the indigenous African sourplum (Ximenia caffra, Olacaceae)

Abstract

Wild-picked fruits of the indigenous African tree, Ximenia caffra, are widely consumed in Southern Africa when in season, yet compositional data on phytochemicals, organic acids and minerals are lacking. The study therefore aimed to characterize juice obtained from ripe X. caffra fruits, and to identify individual phenolic compounds using liquid chromatography, high-resolution mass spectrometry (LC-HRMS). The juice had high total phenolic (1030 mg 100 ml−1 gallic acid equivalents) and total flavonoid content (852 mg 100 ml−1 catechin equivalents), and LC-HRMS analysis identified procyanidin B1 (12.2 mg 100 ml−1), gallic acid (5.56 mg 100 ml−1) and catechin (2.66 mg 100 ml−1) as the most abundant phenolic compounds, while the dominant organic acid was citric acid (8.05 g 100 ml−1), with lesser levels of tartaric, L-malic and L-lactic acids. LC-HRMS further positively identified and quantified a number of other polyphenolic compounds from the juice. The most prevalent minerals were potassium (525 mg 100 ml−1) and phosphorous (24.6 mg 100 ml−1), while heavy metal content was low. Consumption of X. caffra fruits can significantly contribute toward dietary phytochemical and mineral intake, and consumption of this fruit should therefore be encouraged.