Variations in Physical and Chemical Characteristics of Terminalia catappa Nuts

Abstract

Indigenous forest foods have great potential to diversify cropping systems and increase food security and the resilience of food systems to climate change. Underutilised indigenous tree nuts in particular can provide health benefits to local communities and improve livelihoods when commercialised. However, for many tree nut species, there is little knowledge of important kernel characteristics. Kernel size and oil composition are important factors for commercialisation and health benefits, respectively. We assessed kernel attributes of Terminalia catappa L. (Combretaceae), a traditional forest food in the Pacific, in the Solomon Islands, Vanuatu and Fiji. We assessed kernel mass and kernel-to-fruit mass ratio, explored the fatty acid profile of oil, and oil stability against oxidation using accelerated ageing at 45 °C for 21 days. The largest kernels were found in the Solomon Islands with an average mass of 1.66 g. Similarly, kernel-to-fruit mass ratios were higher in the Solomon Islands and Vanuatu than in Fiji. Terminalia catappa contained higher concentrations of unsaturated fatty acids than saturated fatty acids. Among the unsaturated fatty acids, oleic acid and linoleic acid were the two most abundant. Kernels incubated at 45 °C exhibited significantly higher hexanal concentrations on day 7 compared to those on day 0 of incubation. This rapid oil oxidation may be associated with high unsaturated fatty acid concentrations in kernels. These findings may have implications for oil shelf life. Our study suggests T. catappa trees from the Solomon Islands exhibit desirable kernel characteristics that make them suitable for selection and commercialization. The commercialization of an underutilised forest food tree like T. catappa will enhance food and nutrition security for local communities.