In-mouth mechanism leading to the perception of fat in humans: from detection to preferences. The particular role of saliva

In humans, the perception of fat in food is a complex process involving many sensory modalities (texture, aromaand flavour). Themouth is the first place in which the process of digestion begins. During this process, a bolus is formed in which saliva is significantly incorporated. For solids and semi-solid fatty matrices, saliva and the shear forces applied during mastication contribute to their breakdown and/or destabilisation in emulsified systems. These mechanisms are often dependent on the fat content of the food and thus play an important role in not only the perception of texture but also the release of compounds responsible for the flavour of “fat”. In addition, saliva is directly involved in the orosensory detection of triglycerides and their hydrolysis products, i.e., free fatty acids, which occurs at different detection levels, i.e., taste and multimodal. Concerning taste detection, it has been shown that the level of salivary lipolysis is related to the sensitivity of the subject to triolein and oleic acid. Regarding multimodal detection, the antioxidant power and protein composition variables are related to sensory characteristics, such as textural and olfactory perception, of the emulsion. Interestingly, the involvement of some of these salivary variables in the perceived intensity and preference towards model oil emulsions was also shown. In addition to detection, these mouth processes also contribute greatly to a preference for or rejection of fat. Preferences are related to not only the perception of texture but also gustatory and olfactory components of fat