Synthesis of aroma compounds by apples supplied with alcohols and methyl esters of fatty acids

Ester synthesis by apples supplied with alcohols (C2–C8) and methyl esters of short chain fatty acids (C4–C8) was studied using gas chromatographic analysis of the products. The substrates were supplied as vapours to whole fruits stored in 2% O₂ at 3°C. The alcohols were converted to the corresponding acetate ester; butanol, pentanol and hexanol were converted most rapidly. The methyl esters of short chain fatty acids (C_n) were converted to esters with an alkyl group (C_n-2, C_n-4) confirming the presence in whole fruits of an active β-oxidation pathway for fatty acids. Ester synthesis was stimulated when apples were supplied with methyl octanoate at different periods during long term storage in 2% O₂. Treatment of the fruit immediately postharvest did not enhance ethylene synthesis.