Proximate composition, fatty acid and mineral profiles of Trichadenia zeylanica Thwaites nuts: from traditional use to scientific validation

Abstract

Trichadenia zeylanica Thwaites is a plant endemic to Sri Lanka, belongs to the family Achariaceae. It’s commonly known as “Tholol” among the rural communities, and nuts are traditionally consumed as a delicacy. Despite its ethnobotanical uses, this species remains underexplored, and studies evaluating its nutritional potential have not yet been conducted. This study aimed to assess the nutritional composition of T. zeylanica nuts by analysing their proximate composition, fatty acid profile and mineral content. Samples were collected from Weddagala, Kalawana, Sri Lanka (6.4387719 °N, 80.4082348 °E), and subjected to proximate analysis with standard protocols. Fatty acid methyl esters (FAME) were prepared and analysed through gas chromatography-mass spectrometry (GC-MS). Inductively coupled plasma–mass spectrometry (ICP-MS) was utilized to evaluate mineral composition. Proximate analysis showed, nuts are rich in lipids, with a high crude fat content of 56.66±1.36%. These nuts also accounted for 17.53±0.12% of crude protein in their dry weight, serving as a notable plant-based protein source. The carbohydrate content was relatively low at 5.26±1.62%, complemented by a crude fibre content of 5.31±0.09%. The moisture content was 15.12±4.27% and the ash content was 2.55±0.28%. The fatty acid profile showed a composition dominated by saturated fatty acids (SFAs), which constituted over 62% of the total fat content. Palmitic acid was the most prominent SFA. Nuts also consisted 37% of unsaturated fatty acids, most abundantly with linoleic acid. The complex lipid profile warrants further investigation into its health implications. The mineral composition revealed a distinctive and complex profile. The seeds were rich in certain trace elements, such as Rubidium (31.5±0.339 µg/g) and Vanadium (27.4±0.189 µg/g), which are rarely reported in common edible nuts. Essential minerals such as Zinc (7.83±0.574 µg/g) and Copper (3.54±0.135 µg/g) were present at moderate levels. However, the analysis detected presence of heavy metals, including Arsenic, Cadmium, and Lead at trace levels which are below the recommended values. In conclusion, T. zeylanica seeds represent a promising, nutrient-dense wild food source, characterized by high levels of fat and protein, a unique mineral profile, and a complex fatty acid composition. The study scientifically validates nutritional composition and emphasizes the potential for developing of T. zeylanica seeds into a functional food or nutritional supplement through further studies including toxicity assessments.

Keywords: Fatty acid profile, Mineral analysis, Nutritional potential, Proximate composition, Trichadenia zeylanica.