Maturity-driven shifts in physicochemical, phytochemical and mineral composition of marula [Sclerocarya birrea (a. rich.) Hochst] fruit: a multivariate perspective on nutritional functionality

Abstract

Approximately 50% of fruit is lost to postharvest spoilage due to the high metabolic rate of fresh produce. Reducing postharvest losses is crucial in eradicating hunger, reducing poverty and ensuring food security in line with Sustainable Development Goals 1 and 2. Understanding the optimal harvesting time for fruit is essential in maximizing its quality and extending shelf life. This study evaluated the effect of different maturity stages on the physicochemical, phytochemical and mineral profile of marula [Sclerocarya birrea (A. Rich.) Hochst] fruit. The fruit was harvested in the wild at Bushbuckridge-Lillydale (24.872°S 31.365°E) at different maturity stages (mature unripe, semi-ripe and fully ripe) during the summer season of 2025 and transported to the Eureka laboratory at Unisa for analysis. Upon arrival, the fruit were analyzed for physicochemical properties, including total soluble solids (TSS), titratable acidity (TA), pH, TSS/TA, phytochemical properties such as total phenolic content, flavonoids, carotenoids, vitamin C and mineral nutrients. The results revealed that green unripe fruit exhibited a superior total phenolic content of 14.5 GAE/100 g FW, followed by semi-ripe fruit at 10.6 GAE/100 g FW. The lowest total phenolic content was observed in fully ripe fruit at 6.9 GAE/100 g FW. A similar pattern was observed in total flavonoid content. In contrast, vitamin C was highest in fruit harvested at the semi-ripe stage. The findings from this study suggest that marula fruit exhibits varying phytochemical and nutritional contents at the different maturity stages. Therefore, it is essential to harvest it based on targeted phytochemicals or minerals.