Correlation analysis between chemical or texture attributes and stress relaxation properties of ‘Fuji’ apple

Rheological properties of fresh apple have been studied extensively, but the available information concerning the correlation between the rheological properties and quality characteristics is still limited. This study mainly aimed to investigate the feasibility of predicting physicochemical attributes of ‘Fuji’ apple using stress relaxation parameters. Relaxation tests were performed on the intact ‘Fuji’ apple to define the proper relaxation model and parameters through multi-exponential regression. The same sample was described by simultaneous instrumental profiling analyses including texture profile analysis, chemical measurements and stress relaxation test. Models for quality prediction of ‘Fuji’ apples were established and verified based on the variables of relaxation property. A three-term Maxwell model was used to satisfactorily describe the relaxation behaviors of intact ‘Fuji’ apples, and its coefficients of determination were over 0.9995. Significant relationships (p < 0.01) were found between elastic or viscous components and chemical or texture attributes, while the correlations was not significant (p > 0.05) between relaxation time (Ti) and chemical or texture parameters. In regression analyses, effective predictive models were established for all chemical and texture attributes (R2 > 0.80), except for adhesiveness, springiness and cohesiveness, which were less effective (R2 > 0.60). All these results indicate that the measurement of relaxation properties can be deemed as an innovative, reliable and simple method to predict the chemical composition and texture characteristics of ‘Fuji’ apple.