In-vitro and in-vivo flavour release from intact and fresh-cut apple in relation with genetic, textural and physicochemical parameters

The flavour release /intensity of volatile organic compounds (VOC) from six commercial apple cultivars (Fuji, Golden Delicious, Granny Smith, Jonagold, Morgen Dallago and Red Delicious) was measured under static in-vitro (head space of intact and cut fruit) and dynamic in-vivo conditions (nose space analysis) using Proton Transfer Reaction Quadrupole Mass Spectrometry (PTR-QUAD-MS). Textural (firmness, fracturability, flesh elasticity and rupture) and physicochemical (pH, acidity and water content) properties of the apples were also measured. Fuji and Granny Smith apples had the lowest total concentration of VOC (esters, aldehydes, alcohols and terpenes) whereas Red Delicious had the highest concentration. Cut fruit generally had a significantly higher overall VOC concentration than intact fruit with acetaldehyde being the most abundant VOC. Dynamic in-vivo nose space analysis allowed cultivars to be characterized based on mastication time, and the in-nose concentration and relative proportion of the four VOC measured (esters m/z 43, 61; acetaldehyde m/z 45; ethanol m/z 47). Softer varieties (Golden Delicious, Morgen Dallago) were consumed faster releasing more VOCs (particularly esters) and reached a maximum VOC intensity (tmax: 20.5s) faster. Firm varieties (Fuji, Granny Smith) had a longer consumption time, a higher tmax (27.7s) and a lower VOC concentration. Balanced cultivars (Jonagold, Red Delicious) had a tmax of 21.5s and a higher VOC concentration compared to firmer varieties. The diffusion of VOC within the nasal cavity was dependent on particle breakdown during mastication i.e. faster for mealy apples; slower for firm apples. Texture was shown to play an integral role in apple flavour release.