Identification of aroma-active compounds of whole and macerated 'Honeycrisp' and 'Ambrosia' apples

'Honeycrisp' and 'Ambrosia' apples (Malus × domestica Borkh.) are two new popular cultivars with unique textural and flavour properties. However, flavour can be lost during storage or if fruit are not harvested at proper maturity. Identification of compounds responsible for desirable flavour is needed to aid in its optimization. Therefore, to identify and rank aroma-active compounds in 'Honeycrisp' and 'Ambrosia' apple fruit, volatiles were collected on adsorbent collection tubes from whole and macerated fruit of commercial maturity from three orchards. Aroma-active compounds were identified using gas chromatography with mass spectrometry and olfactory detection. A trained sensory panel of six evaluators identified, described and ranked the intensity of aroma-active compounds. In whole 'Honeycrisp' apples, 16 compounds were identified with intensity ratings > 0.1 by panellists representing 9 esters, 3 acids, 1 aldehyde, 1 phenylpropene and 2 unknowns. The most intense aromas were from the esters butyl acetate, ethyl 2-methylbutanoate, hexyl acetate, 2-methylbutyl acetate, and ethyl butanoate and were all described as fruity. In whole 'Ambrosia' apples 25 aroma-active compounds were identified representing 11 esters, 4 acids, 1 alcohol, 1 aldehyde, 1 terpene, 1 phenylpropene, and 6 unknowns. The most intense aromas were from hexyl acetate, 2-methyl butylacetate, butyl acetate, ethyl 2-methylbutanoate and 2-methyl propylacetate, which were also described as fruity. When fruit were macerated to mimic chewing, some compounds were no longer detected and new compounds were produced. Maceration induced substantial quantities of hexanal in both cultivars, which imparts a "green" odour and ranked among the top three compounds for intensity.