Relationships between the instrumental and sensory characteristics of four peach and nectarine cultivars under air and CA atmospheres
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"Big Top" and"Venus" nectarines and"Early Rich" and"Sweet Dream" peaches were picked at commercial maturity and stored for 20 and 40 d at −0.5 °C and 92% RH under either air or one of the three different controlled atmosphere regimes (2 kPa O2/5 kPa CO2, 3 kPa O2/10 kPa CO2 and 6 kPa O2/17 kPa CO2). Physicochemical parameters and volatile compounds emission were instrumentally measured after cold storage plus 0 or 3 d at 20 °C. Eight sensory attributes were assessed after cold storage plus 3 d at 20 °C by a panel of 9 trained judges, in order to determine the relationship between sensory and instrumental parameters and the influence of storage period and cold storage atmosphere composition on this relationship. A principal component analysis (PCA) was undertaken to characterize the samples according to their sensory attributes. PCA results reflected the main characteristics of the cultivars:"Big Top" was the nectarine cultivar with the highest values for sweetness, juiciness and flavor;"Sweet Dream" was the sweetest peach and was characterized by high values for crispness and firmness, while"Venus" and"Early Rich" were characterized by their sourness. To assess the influence of storage period and CA composition on sensory properties, a PLS model of the flavor of the different samples was constructed using standard quality attributes and volatile concentrations as the X-variables. The model with 2 factors accounted for more than 80% of flavor variance. PLS results indicated that the main influence on flavor perception was storage period. Atmosphere composition also had an influence on flavor perception: flavor perception decreased from samples stored in a 2/5 O2/CO2 atmosphere composition to those of 3/10 and 6/17. These results can be qualitatively extended to juiciness and sweetness since all these sensory properties were strongly correlated.