Instrumental and sensory methods to evaluate texture of wheat flour tortillas during storage

Abstract

Subjective reliability, sensory evaluation, and objective rheological techniques characterized wheat flour tortillas on 0, 1, 4, 7, 10 and 13 days of storage. Subjective reliability scores increased during storage (r = 0.80). The 5-member expert sensory panel determined that subjective hardness, reliability, and cohesiveness increased during storage. The 35-member consumer panel failed to detect differences in tortillas stored from 4 to 17 days. Major rheological parameters from extensibility, bending, two-dimensional extensibility, puncture, reliability, and stress relaxation techniques were determined. Force and modulus of deformation (extensibility, puncture, two-dimensional extensibility techniques) and stiffness (stress relaxation technique) were grouped together, had high factor loadings, low CV, and significantly correlated (r = 0.72 -0.98) with subjective reliability score. Rheological parameters within the cluster could predict textural changes during storage. Sensory measures correlated with rheological parameters (r = 0.50 - 0.88) but were not clustered with any objective nor subjective rheological parameter. Rheological characteristics of tortillas (laboratory and commercial) prepared from widely varying dough systems were evaluated during storage. Age of tortillas significantly affected rheological pentameters from extensibility, two-dimensional extensibility, and puncture techniques. Rheological parameters differentiated control, T-1, T-2 and commercial tortillas. Commercial tortillas did not change through the first week of storage as did laboratory made tortillas. Acceptable techniques to measure wheat tortilla texture are extensibility, puncture, two-dimensional extensibility, and stress relaxation techniques. The recommended technique is stress relaxation in tension because it provides information about viscous and elastic properties.