Impact of plant age and harvest season on nutritional profiles of Podocarpus usambarensis oils: Insights from Kahuzi-Biega National Park

Introduction The rising consumption of edible vegetable oils underscores the importance of understanding their nutritional value, particularly in terms of fatty acid composition and vitamin E content. Podocarpus usambarensis is a plant that grows in Kahuzi-Biega National Park in the Democratic Republic of the Congo. It produces oils used by the indigenous population for cooking and medicinal purposes. Purpose This study examines the impact of plant age and harvest season on the fatty acid and tocopherol content of Podocarpus usambarensis oil, highlighting significant differences based on these variables and their implications for public health nutrition. Methods Three samples of approximately 500 g of oilseeds were collected from young and old plants in the dry season, and from young plants in both the dry and rainy seasons. After drying, crushing, and powdering the collected seeds, oil was extracted using Soxhlet's procedure. A drop of oil was methylated, and aliquots were injected into a Varian 5890 gas chromatograph for fatty acid and tocopherol analysis. Results The fatty acids found in the oil were monounsaturated, including oleic and palmitoleic acids; polyunsaturated, including eicosadienoic, eicosatetraenoic, linoelaidic, linoleic, and linolenic acids; and saturated, principally behenic, cerotic, palmitic, and stearic acids. Total saturated fatty acids varied between 10 and 13%. Young trees were significantly (p = 0.043) richer in monounsaturated fatty acids than polyunsaturated ones (53.14% vs. 31.46%), while in old trees, there was no significant difference between polyunsaturated and monounsaturated fatty acids (40.68% vs. 40.59%). Conclusion The plant is an essential source of healthier nutrients, i.e., oleic acid, linoleic acid, and tocopherols. Plant age and seasonal climate impact the yields and composition of these nutrients in Podocarpus usambarensis.