Sensory metabolites profiling in Myristica fragrans (Nutmeg) organs and in response to roasting as analyzed via chemometric tools

Abstract

Nutmeg is a plant grown in tropical region for its seeds distinct flavor, nutritive value and health benefits. Despite extensive studies on nutmeg seed metabolites composition, much less is known regarding volatiles composition in the seed outgrowth mace and fruit and or roasting impact on its flavor. A volatile extraction method was applied for the first time to reveal for nutmeg distinct aroma using headspace solid-phase microextraction (SPME) coupled to mass spectrometry. A total of 53 volatiles were identified belonging to various classes viz., aromatic ethers, monoterpenes and sesquiterpenes. Compared to seeds and mace tissue, fruit was found more enriched in the key flavor “myristicin” 40%. In contrast, monoterpene hydrocarbons amounted as major volatile forms in seeds. Compared to nutmeg fruit, roasted seeds showed a distinct aroma composed of (E)-isoeugenol 16% and methoxyeugenol 11% not detected in fresh seed concurrent with lower anti-nutrient alkaloid levels. GC–MS was further utilized to localize primary metabolites (i.e., sugars and organic acids) and revealing for free sugars abundance in seeds at 47% versus enrichment of organic acids 58% viz. malic acid in fruit, and accounting for the later less palatable taste. This study provides the most comprehensive map for sensory metabolites distribution in nutmeg.