Sensory interpretation of instrumental measurements 1: texture of apple fruit

Abstract

The relationship between instrumental and sensory measurements of apple texture was investigated. The aim was to determine the instrumental tests that were best correlated with sensory measurements, and then to identify the minimum instrumental difference that was required before a trained sensory panelist could detect a difference in apple texture. Instrumental tests included puncture, tensile, twist, and Kramer shear tests, as well as the recording of chewing sounds, and a non-destructive test based on impact responses of fruit (SoftSense). Sensory panelists were trained to assess a wide range of texture attributes including crispness, crunchiness, hardness, juiciness, ease of breakdown, and mealiness. The three instrumental tests that best predicted a sensory response were puncture, twist and chewing sounds. In general, puncture tests were better at predicting sensory texture attributes than either tensile measurements or chewing sounds, which were not significantly different from each other. Calculations of minimum instrumental difference evoking a sensory response in a trained panelist focused on the puncture test. A firmness difference of 6 N (obtained using an 11 mm diameter Effegi probe) was required before the average trained panelist could detect a difference in fruit texture ( P =0.90). This 6 N value represents the firmness above which there is high certainty that a trained panel will detect a texture difference. However, the study demonstrated that some textural differences between apples were not always adequately predicted by instrumental test. Thus, we recommend that assessment of fruit by trained and/or consumer panels remain a critical part of fruit quality assessment.