6533b86efe1ef96bd12cb012

RESEARCH PRODUCT

Sensory analysis with consumers using Free-Comment : analyses, performances and extensions

subject

description

Free-Comment (FC) consists in panelists describing the products using their own terms. Despite its benefits, notably the circumvention of limitations inherent to pre-established lists of sensory descriptors, FC remains rarely used because its performances are not well documented and its analyses and range of application remain limited. This thesis aims to overpass these limitations, highlighting the benefits and the potency of FC and thus put it in the spotlight for sensory analysis with consumers.For the pretreatment of FC data, a semi-automatized procedure is proposed. It enables the practitioners to extract an a posteriori list of sensory descriptors with a compromise between minimizing the loss of information and maximizing the quickness of the pretreatment. For the statistical analysis of FC data, operating in the significant subspace of product by sensory descriptor dependences is proposed together with the multiple-response chi-square framework that better takes into account the structure of the pretreated data than the usual chi-square framework. These analyses have been implemented into a R-package downloadable from GitHub.The performances of FC have been compared to those of Check-All-That-Apply (CATA), the most popular method for descriptive sensory analysis with consumers. Two performance criteria have been investigated: the discrimination power and the stability of the product characterization. Regarding both criteria, FC turned out to perform as well as CATA, if not better.Two extensions of FC are proposed. The first one, Free-Comment Attack-Evolution-Finish (FC-AEF), directs the descriptions towards the temporal aspect of the sensory perception. The second one, Ideal-Free-Comment (IFC) paired with liking scoring, identifies the drivers of liking and characterizes the ideal product thanks to FC. An application of these two methods was carried out, demonstrating their ability to fulfill their aims.Overall, this work demonstrated the potency and the versatility of the FC method. It opens new perspectives for sensory analysis with consumers and it should promote a larger use of FC in that field.