Sensory profile of port wines: Categorical principal component analysis, an approach for sensory data treatment

Abstract

Port wine is a fortified wine. After the grape spirit addition the fermentation stops and the wine retains some of the natural sweetness of the grape. Port wine exhibits a variety of different styles, each with its own characteristic flavours: White Ports, Ruby Ports and Tawny Ports. Information about the wines sensory characteristics is critical for the successful development and marketing of each new wine brand. This type of information can be obtained using descriptive sensory tests with trained panels that can recognize different sensory descriptors in wines. Given that the collected variables are measured on an ordinal scale a Categorical Principal Component Analysis (CATPCA) can be performed. However, for many years, multivariate analysis has been used for wine characteristic evaluation and Principal Component Analysis (PCA) has long been applied to sensory data treatment. The two main purposes of this study were to describe a specific sensory method, used by a trained sensory panel including chemical compounds reference development, to establish the most important descriptive and discriminative sensory attributes of different Port wine styles and brands and to compare the results of PCA with the results of CATPCA, in order to assess the feasibility of both techniques. At the end of the work we have demonstrated that the CATPCA data analysis seems to be more robust and explained 15% more of the total amount of initial variance than PCA. Moreover, the CATPCA model did not highlight differences among wines from winery brands while, in PCA, Port Wines are grouped according to wine style and there are some discrimination between brands.