Free and glycosidically bound volatiles in the mammee apple (Mammea americana) fruit

Abstract.

The volatile constituents of mammee apple (Mammea americana) fruit pulp obtained by liquid-liquid extraction were analyzed by capillary GC and capillary GC-MS. In total, 51 components (40 of which are identified for the first time in mammee apple) were identified with methyl 3-hydroxy-2(S)-methyl propanoate pure enantiomer and 2-methyl butanoic acid with ee 98.5% S being the major components. Glycosidically bound aroma compounds were identified by capillary GC and capillary GC-MS after isolation of the glycosidic fraction obtained by Amberlite XAD-2 adsorption and methanol elution followed by hydrolysis with a commercial pectinase enzyme. In total 19 bound aroma compounds (aglycones) were identified. These aglycones mainly consisted of carboxylic acids and C₁₃-norisoprenoids of which 2-methyl butanoic acid, 4-hydroxy-β-ionone and 4-oxo-β-ionol are the most representative. Additionally, with the aid of capillary GC-MS (EI and NCI) of trifluoroacetylated derivatives we identified eight glucosides: glucopyranosyl methylbutanoate (two isomers), glucopyranosyl methylbutenoate (two isomers), methyl 3-O-β-D-glucopyranosyl 2-methylpropanoate, methyl 3-O-β-D-glucopyranosyl 2-methylbutanoate, 4-oxo-β-ionyl 9-O-β-D-glucopyranoside and 4-oxo-7,8-dihydro-β-ionyl 9-O-β-D-glucopyranoside.