Does Fat Alter the Cortical Response to Flavor?

• Published in: Chemosensory perception 2012-12, Vol.5 (3-4), p.215-230
• Main Authors: Eldeghaidy, Sally, Hollowood, Tracey, Marciani, Luca, Head, Kay, Busch, Johanneke, Taylor, Andrew J., Foster, Tim J., Spiller, Robin C., Gowland, Penny A., Francis, Sue, Hort, Joanne
• Format: Article
• Language: English
• Subjects: Amygdala; Aroma; Brain; Brain mapping; Chemistry; Chemistry and Materials Science; Chemoreception; Clinical Nutrition; Cortex (cingulate); Cortex (somatosensory); Flavor; Flavors; Food Science; Functional magnetic resonance imaging; Information processing; Mouth; Neurosciences; NMR; Nuclear magnetic resonance; Oils & fats; Oral cavity; Perception; Reinforcement; Sensory evaluation; Sensory perception; Sensory properties; Taste; Thalamus; Viscosity; Volatiles
• ISSN: 1936-5802; 1936-5810
• DOI: 10.1007/s12078-012-9130-z

Understanding the impact of fat in the oral cavity on the cortical response to flavor may aid the design of healthier low fat products which are acceptable to the consumer. However, varying fat content affects physicochemical and sensory properties, making it difficult to isolate the impact of the fat itself. The objective of this study was to investigate the interaction between fat and the cortical response to flavor, using a model emulsion system that enabled confounding factors, such as changes in volatile release and viscosity, to be controlled. Initial sensory and volatile release studies were performed to formulate four fruity emulsion samples, all iso-sweet and iso-thick, for use in the functional magnetic resonance imaging study: an unflavored fat emulsion; a flavored no-fat stimulus; and two further flavored fat emulsions, one iso-volatile release and one iso-perceived in fruit flavor intensity compared with the no-fat stimulus (the former containing less volatile). Stimuli were found to activate a large network of brain areas including the somatosensory cortices (SI and SII); anterior, mid, and posterior insula; anterior cingulate cortex amygdala, and thalamus. Overall, the flavored, no-fat stimulus led to increased activation compared with flavored and unflavored fat emulsions in areas relating to reward, taste, aroma, and somatosensory processing. Sensory data indicated that the only perceivable difference between the no-fat stimulus and fat emulsions was in the level of the oily/greasy film/residue left in the mouth which the panel termed “oiliness,” indicating this to be an important stimulus for the presence of fat in the oral cavity in these samples. The dampening effect of fat on cortical activity was somewhat reduced by increasing the volatile component of the stimulus without changing the perceived flavor.