Internal and External Quality Mapping as a New Approach to the Evaluation of Sensory Quality – a Case Study with Olive Oil
Article first published online: 5 OCT 2012
© 2012 Wiley Periodicals, Inc.
Journal of Sensory Studies
Volume 27, Issue 5, pages 332–343, October 2012
How to Cite
Delgado, C. and Guinard, J.-X. (2012), Internal and External Quality Mapping as a New Approach to the Evaluation of Sensory Quality – a Case Study with Olive Oil. Journal of Sensory Studies, 27: 332–343. doi: 10.1111/joss.12000
- Issue published online: 5 OCT 2012
- Article first published online: 5 OCT 2012
- Manuscript Accepted: 30 JUL 2012
The preference mapping approach was extended to the investigation of sensory quality in extra virgin olive oil (EVOO), and this article describes a new methodology – internal and external quality mapping – which can be used to uncover and measure the positive and negative drivers of sensory quality as perceived by experts. A panel of 23 olive oil experts evaluated 22 EVOOs for the intensity of the sensory attributes in the International Olive Council scorecard on a 10-cm scale, and then rated their overall sensory quality on a 100-point scale. In parallel, a descriptive analysis panel rated the intensity of 22 sensory attributes. The quality ratings by the experts were analyzed by principal component analysis (e.g., internal quality mapping), and were then related to the descriptive analysis ratings using regression methods (e.g., external quality mapping). No significant segmentation was found in the quality ratings of the experts, indicating that the experts' concept of quality was homogeneous. Through a regression of the quality ratings into a factor analysis, biplots of the sensory attributes showed that ripe and green fruit, nutty, grassy, bitter and pungent flavors were positive drivers of quality for the experts, whereas rancidity and fustiness were negative drivers.
Internal and external quality mapping is proposed as a validation tool for the assessment of sensory quality by experts. It uncovers potential segmentation among the experts and it identifies the sensory drivers of their concept of sensory quality.
Understanding how experts interpret quality in extra virgin olive oil will also be beneficial for producers and marketers because they often bridge between them and the consumers, similar to the wine industry, where experts play a fundamental role in guiding consumers' purchase decisions.