Aroma quality of Gravenstein apples influenced by regular and controlled atmosphere storage

Abstract

Gravenstein apples were stored at 2°C in regular atmosphere for 21/2 mo and in controlled atmosphere for 31/2 mo. Firmness, soluble solids, titratable acids, sensory quality and volatile compounds were measured both in newly harvested and stored apples. Firmness, soluble solids and titratable acids decreased during storage, but only the soluble solids/titratable acids ratio was affected by the storage treatment, controlled-atmosphere apples having lower ratio than the regular-atmosphere apples. Stored apples were sensory characterised by apple, acidic and fresh odour. Apples at harvest were described as more grassy. The most abundant volatile compounds in Gravenstein were 1-butanol, 2-methyl-1-butanol, 1-hexanol, ethyl butanoate, butyl butanoate, hexyl butanoate, hexyl hexanoate and α-farnesene. The compounds having the highest aroma values (concentration/odour threshold) were ethyl butanoate, ethyl 2-methylbutanoate and ethyl hexanoate. Ethyl butanoate could be an appropriate ripeness-indicator compound in Gravenstein due to its increasing concentration during storage, and its high aroma value. Levels of volatile compounds, especially compounds contributing to the overall aroma, increased during storage. Total aroma value increased 16 times in the regular-atmosphere apples and 12 times in the controlled-atmosphere apples compared to the apples at harvest. © 2002 Published by Elsevier Science Ltd.