Organoleptic validation of a color masking system specified for green and black tea (Camellia sinensis L.) brews

Abstract

Numerous studies focusing on organoleptic tests have shown that the visual characteristics of the product under study cause a preconception (expectation error) in the judge, which distorts the perception of the other sensory characteristics to varying degrees. In cases where the rating is not based on visual judgment, it is advisable to ensure test conditions where it can be ruled out that the color stimulus of the product does not influence the decision of the judges [1]. Consequently, it is necessary to reduce the intensity of color sensation or the quality of the sensation, but most of all to mask them. The methods widely used in practice (blindfolding, colored vessels, colored lenses, etc.) are subject to distortions, therefore, a spectrally adjustable lighting system specified for the types of the given product can provide a solution to eliminate these by optimizing the parameters of the observation and by the sensory validation of them. The said spectrally adjustable LED measuring system with a homogeneous light distribution is controlled by arduino (an open-source electronic prototyping platform enabling users to create interactive electronic objects - ed.). In our study, the organoleptic validation of a color masking system specified for green and black tea (Camellia sinensis L.) brews is presented. Participants of the experiment were tested according to international standards [2, 3]; based on our test results, they had normal vision in all respects. The results showed that, by color masking the smallest detectable threshold value and by determining the spectral characteristics, differences in visual perception between sample pairs with a certain difference in color stimulus can be partially or completely masked. As a result, under perfectly masking illumination, expectation errors due to perception do not distort the judgment of the other organoleptic characteristics (such as smell, taste, texture and mouth coating) of tea brews. Partial masking eliminates color differences in many cases, increases judgment time 4 to 8-fold, however, differences due to brightness remain observable.