Evaluating temporal multiple sip approaches to characterise product experience : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North Campus, New Zealand

Abstract

As consumers become ever more demanding, methods that capture detailed insights into consumer product experiences are much needed. Adapting temporal sensory and affective measures to cater this demand beyond single time points and small sample sizes is one such approach, and of a recent interest in the sensory and consumer science research area. Firstly, this research compared single and multiple sip sensory approaches using static and time-dependent sensory methodologies with an expert panel. Multiple sip evaluations were designed to represent the consumption of a whole product serving, in this case vanilla milkshakes. Generalised linear models with Analysis of Deviance were employed as a novel approach to analyse naturally correlated temporal data. Additionally, the impact of milkshake sipping method and panel type on multiple sip temporal profiles of the milkshakes was investigated. In addition, temporal methods were adapted to investigate consumer affective responses, both hedonic and emotional response, over multiple sips. Temporal drivers of product acceptance and rejection were identified in analyses combining sensory and affective data. Finally, the impact of individual differences in sweet liker and PROP (6-n-propylthiouracil) taste phenotypes across multiple sip temporal emotion profiles of the milkshakes was investigated. Multiple sip evaluation of both static and temporal methods (Temporal check all that apply (TCATA) and Temporal dominance of sensation (TDS)) provided further discrimination of products than on a single sip of milkshakes. The use of static and temporal methods as complementary approaches, rather than as alternatives, was valuable in obtaining holistic temporal profiles of products. Specifically, the use of generalised linear models and Analysis of Deviance allowed to investigate the dynamics of within-sip and between sip which was a novel addition to the knowledge of temporal data analysis. However, temporal sensory product profiles varied depending by sipping method and emphasised the importance of adapting product evaluation protocols based on intended consumption methods of the beverages. Moreover, temporal sensory profiles were affected by panel type, i.e. experts or consumers, and the insights obtained from the two panel types were not interchangeable. Using expert panels, even on multiple sip evaluations did not provide closer insights into actual consumer product experience. The research highlighted that choice of panel type needs to be aligned with any respective project objectives. Temporal sensory responses of consumers were associated with temporal liking and emotions over multiple sips. Furthermore, dominant emotions reported depended on sweet liker status and PROP taster status. The research findings highlighted the importance of investigating temporal affective responses, i.e. both liking and emotions, and individual differences alongside temporal sensory responses in consumer research to obtain closer insight into actual product experience. Generally, findings were attribute and product specific and hence wider research using additional products and different food matrices are required to validate the findings. Overall, the research outcomes emphasised the importance of multiple sip sensory evaluations to represent the consumption of whole product servings, using appropriate sipping methods, and panels. Investigating the affective responses and individual differences were important to capture different insights according to respective project objectives.