Bioactive compounds and total antioxidant capacity of nuts of selected cashew (Anacardium occidentale L.) varieties in Sri Lanka

Abstract

Cashew (Anacardium occidentale L.), a tropical nut tree, produces nuts rich in bioactive compounds and antioxidants. The prospective health benefits of cashew nuts and their by products, particularly those associated with antioxidants and bioactive compounds, have garnered increasing attention. The research aimed to evaluate the total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant capacity (TAC) of whole nuts, kernels, and testa of thirteen high-yielding cashew varieties (i.e., WUCC 1, WUCC 2, WUCC 5, WUCC 7, WUCC 8, WUCC 9, WUCC 13, WUCC 16, WUCC 19, WUCC 21, WUCC 23, Shakthi and Wijanitha) in Sri Lanka. TPC, TFC, and TAC were determined using the modified Folin-Ciocalteu method, AlCl3 method, and ferric reducing antioxidant power (FRAP) assay, respectively. The study revealed that the testa of all thirteen high-yielding cashew varieties had significantly higher TPC, TFC, and TAC compared to whole nuts and kernels, with ranges of 55.83 ± 0.95 to 62.24 ± 0.99 mg GAE/g DW, 452.35 ± 19.29 to 642.10 ± 14.63 mg RE/g DW and 407.48 ± 7.02 to 620.13 ± 46.39 mg TE/g DW, respectively. The lowest values were recorded in the kernels of all the thirteen varieties. Strong positive correlations were found between TAC and TPC (R²= 0.9773, p<0.0001) and between TAC and TFC (R² = 0.974, p<0.0001) indicating that flavonoid and phenolic compounds are the primary contributors to antioxidant capacity. These findings highlight the potential for selecting cashew varieties with elevated phenolic and flavonoid content to improve overall antioxidant capacity. Moreover, the study suggests that the cashew testa, often discarded as a by product, is rich in bioactive compounds and antioxidants and can be utilize in developing value added products that promote health and longevity.