# FaceReader Insights into the Emotional Response of Douro Wines
## 1 Introduction  
Nowadays, the emotional state of consumers has become a widely applied marketing strategy to increase consumption, as emotions play a fundamental role in the process of purchasing a product [1, 2, 3]. Assessing wine extends beyond just sensory analysis; it includes an experience of an emotional response that is intrinsically linked to their sensory perception [4, 5]. This emotional response can significantly influence how products are evaluated and preferred by consumers [6, 7, 8]. Emotions are a systematic array of chemical and neuronal responses generated by the brain upon detecting an emotionally significant stimulus, such as an object or situation. These responses involve biochemical processes and neural activity that influence an individual's emotional state, affecting their behavior and perceptions [9, 10, 11]. Remarkably, the emotional evaluation of wine involves grasping the delicate intricacies of its flavor, texture, and bouquet, which together create a comprehensive experience. This experience can stir emotions such as pleasure, nostalgia, or even excitement, enhancing the overall pleasantness of the wine [12].  
The quantification of emotions through facial expressions has been extensively studied in psychology and has sparked interest in evaluating basic emotions during the consumption of food products [13]. In response to this premise, the FaceReader program (by [PERSON], Wageningen, The Netherlands) was developed, an innovative computational system thatallows the direct capture of facial expressions of an individual exposed to a stimulus and the quantification of basic emotions over a defined period. The organoleptic properties of beverages significantly influence consumer behavior, as they can trigger involuntary facial expressions [14; 15; 16; 17]. The FaceReader system is software that detects facial expressions within a short time frame and classifies them into seven categories: happy, sad, angry, surprised, scared, disgusted, and neutral, although it is possible to add more expressions to the system. It operates in three phases: discovering, modeling, and classifying the consumer's face. This evaluation has been recently applied in food and beverage tasting contexts due to the emotional, descriptive information detected and the real-time acceptance of products [18].  
However, while several studies use the advanced facial recognition software FaceReader to correlate emotions with other types of food and beverages [5; 19; 20; 21; 22], there is a notable gap in research explicitly examining the emotional reactions elicited by different types of wine, notably including one of the remarkable wines in the Douro region, Port wine. Although a study by [PERSON] et al. [5] investigated emotional responses to white and red wines, it did not explore Port wine, leaving a gap in understanding how this unique category of wine affects consumer emotions.  
This study aims to investigate the emotional responses elicited by different types of Douro wines (white, red, and Port wine) using the FaceReader software. By analyzing facial expressions during wine tasting, the study seeks to identify and quantify the emotions associated with the consumption of various wine categories, providing insights into how these emotional reactions correlate with the sensory characteristics of the wines.