Development of a consumer-driven chocolate milk sensory ballot for use in the dairy industry

Abstract

Chocolate milk is an important dairy product in the United States, but current sensory ballots used to assess product quality and defects lack relevance for consumer-identified attributes of importance. Therefore, the objective of this research was to describe commonly encountered variation in desirable and undesirable attributes in commercially processed chocolate milk products, and to develop and test an improved expert sensory assessment ballot for chocolate milk. Eighteen commercially processed chocolate milk samples were collected and evaluated instrumentally for color parameters, and with an expert panel and a consumer panel for sensory properties. Significant differences in color parameters, as determined instrumentally, were found between the samples. A 9-point chocolate milk color scale was created based on these variations and used in this study. A trained milk quality panel assessed the samples using a historic chocolate milk expert sensory assessment ballot that was largely focused on end of shelf-life defect identification based on American Dairy Science Association guidelines for unflavored milk. The panel found the chocolate milk samples to vary widely in color, chocolate character, and other sensory attributes. Panelists noted an increase in defect detection and a decrease in sweetness and chocolate character with shelf life, attributes not included in the historic ballot. A subset of 6 chocolate milk samples stored at 3°C (control condition) and at 8°C for 5 d (representing accelerated shelf life) was subsequently assessed by consumers. Overall liking and quality scores were highly correlated, with both significantly decreasing for the accelerated shelf-life samples compared with the control condition. Whereas no significant differences in color were found, chocolate aroma and flavor significantly weakened, and the presence of atypical aromas and flavors significantly increased in the products held under accelerated shelf-life conditions. Outcomes from these experiments were used to update the existing expert sensory assessment ballot to capture consumer-relevant product attributes consistently across shelf life, in addition to defect monitoring. Finally, we compared data on expert sensory assessment of commercially processed chocolate milk products collected using the original and the updated ballots. Whereas no significant differences in assigned overall quality mean scores were noted between the 2 ballots, the updated ballot facilitated tracking of chocolate milk character changes that were important to consumers over the shelf life of the product. This study provides guidance to the dairy industry, in particular, manufacturers of chocolate milk, to both improve chocolate milk characteristics that effect consumer liking, as well as methods for monitoring these characteristics over product shelf life.