Role of free fatty acid signaling in oral detection of fat
Abstract
High fat foods are palatable and energy dense. They are often blamed for the epidemic of obesity. Recent data suggest that free fatty acid (FFA) signaling may act as a primary taste, “fat taste” that plays a crucial role in the oral detection of fat in addition to textural and olfactory cues. However, fats are predominantly present as triacylglycerol in the human diet. The possible in-vivo role of lipases to release FFAs into saliva from high fat foods during oral processing is not clear. This study identified and quantified salivary FFAs generated during oral processing of high fat foods. The role of lingual lipase was determined by contrasting salivary FFA concentrations achieved during oral processing of fatty foods in the presence and absence of a lipase inhibitor, Orlistat. Participants chewed (at the rate of one bite/sec for a minute) and expectorated high fat foods. The foods varied in physical state (solid, semi-solid and liquid) and fatty acid composition (saturated, monounsaturated and polyunsaturated). Qualitative and quantitative analyses of salivary FFAs obtained from expectorated samples were performed by GC-MS. Lauric, palmitic, oleic, linoleic, linolenic and stearic acids were the major salivary FFAs and their concentrations were in the range of 20 to 60 micromolar. Each food produced a signature salivary FFA profile that reflected its fatty acid composition. Orlistat did not suppress FFA concentrations except for foods that had a hard matrix and hence required more force during chewing. Orlistat did not alter sensory ratings of almond butter, a high fat food. Future electrophysiological studies are required to determine the threshold for excitation of human taste receptor cells by FFAs to determine whether the salivary FFA concentrations observed in this study are adequate to activate gustatory FFA signaling.
Degree
Ph.D.
Advisors
Mattes, Purdue University.
Subject Area
Nutrition
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