A multivariate approach into physicochemical, biochemical and aromatic quality changes of purée based on Hayward kiwifruit during the final phase of ripening

The current work monitored a wide range of quality attributes of purée based on kiwifruit (Actinidia deliciosa, 'Hayward') during the final phase of ripening. A targeted approach was used to analyze texture, color, sugar, acidity and activity of specific enzymes. A headspace gas-chromatography mass-spectrometry analysis was used as an untargeted approach to fingerprint the volatile fractions. A multivariate data analysis approach was used combining all quality parameters (targeted and untargeted) in order to determine the most important attributes changing during late ripening. This work demonstrated that hardness, color, sugars, acids (malic and ascorbic acid) and esters and aldehyde headspace compounds were the quality indicators, changing most during kiwifruit late ripening. During late ripening, hardness decreased significantly and soluble solids content increased. The color of kiwifruit purée turned dark and less green. Sucrose decreased significantly with glucose and fructose increasing accordingly. Titratable acidity and major organic acids (quinic and citric acid) showed a similar trend increasing at start of late ripening stage and then decreasing, however malic and ascorbic acid consistently decreased during ripening. Pectin methylesterase and β-galactosidase increased and then declined, whereas peroxidase consistently increased. The formation of esters, such as methyl hexanoate and ethyl hexanoate, and a decrease of aldehydes, like hexanal, heptanal and (E)-2-hexenal, was observed. Therefore, the present work clearly demonstrated the potential of the multivariate approach to zoom into important quality indicators for the final phase of kiwifruit ripening. The outcome can provide useful information for ripening stage evaluation of kiwifruits in the processing industry.