Mechanical properties and sensory evaluation of selected apple cultivars

Abstract

Selected commercial apple cultivars (Golden Delicious, Stark Delicious, Renetta, Annurca, Granny Smith, Emperor) were studied to discriminate among the cultivars and the different levels of merceological quality for their mechanical and texture characteristics, by instrumental and sensory methods. Single compression, double compression and penetration tests were carried out to determine mechanical and texture properties of the apple flesh (failure stress and strain, modulus of deformability, juiciness, cohesiveness and firmness). Sensory responses were obtained by the descriptive technique of texture profile analysis and by the pairwise ranking test (paired comparisons of more than two samples) for the following parameters: fracturability, firmness, cohesiveness, mealiness and juiciness. Annurca and Granny Smith cultivars showed the highest values for almost all the instrumental and sensory parameters measured. The instrumental methods indicated that the internal variability of flesh structure influenced the differences among the cultivars, although some significant differences were clear. Results from the correlation study between instrumental and sensorial parameters were affected by the non-homogeneous distribution of the values in the correlation plots, probably due to the low number of samples considered. Principal component analysis applied to the instrumental results showed that the first two components described about 85% of the total variance. The first component was a linear combination of five variables, excluding the failure strain, while the second was a failure strain factor. It seems that only two parameters, the failure stress for instance and the failure strain, would be sufficient to point out differences among the cultivars and the merceological quality levels considered. © 1993 Academic Press. All rights reserved.