Effect of long-term freezing storage on the phytochemical and nutritional composition of Ximenia americana L. fruit

Abstract

This study investigates changes on the proximate composition and phytochemical profile of the non-polar fraction of Ximenia americana fruit parts at the storage period of 6 months at − 4 °C. Additionally, changes on the mineral elements and anti-nutritive compounds content were analyzed. Proximate analysis refers to the content of 6 components: moisture, ash, carbohydrates, proteins, fats and dietary fiber. In this investigation, only three components were analyzed: fats, moisture and ash. Non-polar fractions of fruit parts were also analyzed by GC-MS. Ximenia americana L. is an indigenous edible wild plant widely used across Southern Africa. The results showed that mineral elements such as Mg, K, Ca, Cu, Mn, Ni, and Fe were well preserved during the entire frozen storage period, with K and Ca being the most retained across the fruit parts. The proximate and antinutrient (oxalates, alkaloids and tannins) components also showed varying degrees of preservation. Although the antinutrients showed a certain degree of retention, their recorded values in the kernels of X. americana fruit are below the permissible toxic levels, except tannins in the pulp after harvest (post-harvest) relative to the previous limit by FAO/WHO. The phytochemicals showed significant variations except for alkane hydrocarbons. Losses in nutritional quality mostly occurred in the first month after freezing. Taking into consideration some essential nutrient losses: Na, Mg, Zn and Mn, to effectively contribute to nutritional needs and food security, it would be necessary to preserve X. americana fruits by frozen storage and use it within a period not exceeding 6 months.