Biosynthesis of 2-Methylbutyl, 2-Methyl-2-butenyl, and 2-Methylbutanoate Esters in Red Delicious and Granny Smith Apples Using Deuterium-Labeled Substrates

• Published in: Journal of agricultural and food chemistry 1996-10, Vol.44 (10), p.3276-3285
• Main Authors: Rowan, Daryl D, Lane, Heather P, Allen, John M, Fielder, Simon, Hunt, Martin B
• Format: Article
• Language: English
• Subjects: ACIDE GRAS VOLATIL; ACIDO GRASO VOLATIL; APPLES; AROMA; Biological and medical sciences; COMPOSE VOLATIL; COMPUESTO VOLATIL; CULTIVARS; ESTER; ESTERES; ESTERS; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; ISOTOPE LABELING; MANZANA; METABOLISM; METABOLISME; METABOLISMO; ODEUR; OLOR; POMME; SMELL; TECHNIQUE DES TRACEURS; TECNICAS DE TRAZADORES; TRACER TECHNIQUES; VARIEDADES; VARIETE; VARIETIES; VOLATILE COMPOUNDS; VOLATILE FATTY ACIDS
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf9508209

2-Methylbutanoate esters, especially ethyl 2-methylbutanoate, are key contributors to fruit aroma. The biosynthetic origins and interconversions of 2-methylbutyl and 2-methylbutanoate esters in Red Delicious and Granny Smith apples were determined by feeding deuterium-labeled substrates with GC−MS identification of the deuterated aroma volatiles produced. Deuterium-labeled isoleucine was fed to apple peel, and 2-methylbutanoic-d 3 acid, 2-methylbutanol-d 3, and ethyl 2-methylbutanoate-d 3 were fed as vapor to whole apples. An array of labeled 2-methylbutyl and 2-methylbutanoate esters was produced from each substrate with significant differences in products and product distributions between the two apple cultivars. Novel 2-methyl-(2E)-butenyl esters were identified as biosynthetic products in the aroma of Red Delicious but not Granny Smith apples. Keywords: Biosynthesis; apple; aroma volatiles; 2-methylbutyl; 2-methylbutanoate; 2-methyl-2-butenyl; deuterium