Development of cocoa physical reference samples for training and calibration of sensory evaluation panels: perspectives from a range of food products

There is an urgent need to build capacity in cocoa producing countries of sensory panels and quality laboratories for the assessment of cocoa quality and flavour, for a better understanding of potential for increased value and profitable production. Cocoa of Excellence is leading the way in partnership with key sensory experts and organisations in the development of International Standards on the Assessment of Cocoa Quality and Flavour (ISCQF).

Physical reference samples are critical for supporting training sensory evaluation and generating a commonly agreed understanding through a common language and glossary of terms. Therefore, establishing physical references for cocoa products are essential to ensure sensory evaluation panel members' performance in terms of repeatability, discrimination and alignment.

Several food products such as olive oil, wine and coffee have developed standard procedures for sensory evaluation. These include glossaries of terms, physical reference samples for odours and flavours, and evaluation forms. These provide useful models to promote science-based approaches to assessing cocoa quality.

The objective of this research was to review the use of physical reference samples of different food products, to guide the development of such references for training and calibration of sensory evaluation panels for cocoa products.

A review of literature of 149 articles was carried out. The main references were grouped by product and analysed on what type of sensory analysis method was used, for which purpose, and the type of reference samples used. The analysis resulted in recommendations for the development of cocoa-specific physical references.

Additionally, this paper shows preliminary results of pilot trainings carried out using the Cocoa of Excellence set of physical reference of different types including chemical, food-based, non-food-based and matrix based. The results show improvements at individual and panel level and show the potential of these to strengthen the capacity of national cocoa liquor sensory evaluation panels.

Keywords: physical reference samples, sensory evaluation, quality assessment, training, calibration.