Physicochemical, Phytochemical, and Antinutritional Characterization of Seed Shells from Five Hevea brasiliensis Clones Cultivated in Côte d’Ivoire

Abstract

In the context of diversifying the incomes of rubber tree growers and promoting a circular bioeconomy, the valorisation of by-products from Hevea brasiliensis cultivation represents a promising pathway toward the sustainable development of the sector. In Côte d’Ivoire, the National Agricultural Research Centre (CNRA) has developed processes for extracting oil and meal from rubber seeds, which generate abundant shell residues that remain underutilised. This study aimed to characterise the physicochemical, phytochemical and antinutritional properties of seed shells from five Hevea brasiliensis clones commonly cultivated in Côte d’Ivoire (GT1, PB217, IRCA230, IRCA331 and IRCA41) in order to assess their potential for agro-industrial valorisation. The analyses revealed significant inter-clonal variability. Clones IRCA230 and IRCA41 exhibited higher levels of lipids (up to 9.84%), tannins (3.43 mg EAT/100 g) and polyphenols (5.20 mg EAG/100 g), indicating strong antioxidant potential suitable for cosmetic, pharmaceutical and food applications. In contrast, GT1, PB217 and IRCA331 showed higher fibre contents (up to 83%) and total sugars (23 mg/100 g), suggesting potential for energy recovery and biomaterial production. Antinutritional factors such as phytates (30–186 mg/100 g), oxalates (55–81 mg/100 g) and hydrocyanic acid (16–21 mg/100 g) were present at moderate, non-toxic levels. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) clearly differentiated two groups of clones according to their biochemical profiles. Overall, the results demonstrate that rubber seed shells often considered waste constitute a valuable lignocellulosic resource for the extraction of bioactive compounds and the development of eco-materials, thereby contributing to the sustainability and competitiveness of the Ivorian rubber sector.