Antioxidant Properties and Proximate Composition of Sri Lankan Nutmeg (Myristica fragrans Houtt.)

Nutmeg is a high-value spice whose biochemical and nutraceutical properties vary with geographical origin and germplasm. Although the antioxidant properties of Sri Lankan nutmeg have been studied previously, the findings are not representative of the broader germplasm, and the proximate composition of Sri Lankan nutmeg remains unknown. Hence, in the present study, the proximate composition, antioxidant content, and antioxidant activity of the mace, kernel, and pericarp of Sri Lankan nutmeg were assessed using samples collected from Kandy, Matale, and Kegalle districts. Proximate analysis indicated a significant (p < 0.05) variation in moisture, crude fat, crude fiber, and ash content among the mace, kernel, and pericarp. Interestingly, the crude fat content of the kernel was two-fold and 21-fold higher compared to the mace and pericarp, respectively. Furthermore, the crude protein content in the mace and kernel was significantly (p < 0.05) higher than in the pericarp, showing nearly a two-fold difference. The antioxidant assays revealed that the mace had the highest total phenolic content (TPC: 24.50 mg GAE/g), total flavonoid content (TFC: 93.20 mg RE/g), and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH-RSA: 33.09 mg TE/g). The ferric ion reducing ability, assessed by the FRAP assay, showed no significant (p > 0.05) differences among the mace, kernel, and pericarp. Overall, the mace was superior in terms of antioxidant properties, followed by the kernel. Although the pericarp did not contain as high TPC, TFC, and DPPH-RSA levels as the mace and kernel, its electron-donating ability in the FRAP assay indicates the potential value of these otherwise discarded nutmeg by-products. This study highlights the potential applications of nutmeg in industries beyond its traditional use as a spice.