Taste sensitivity and multisensory interactions in relation to the nutritional status

INTRODUCTION Obesity is considered a disease with a multifactorial etiology. Although it is well known that taste plays a crucial role in eating behavior literature data about the relationship between taste and nutritional status are controversial [1-3]. Among the causes involved in the development of this pathology, high availability of high-density energy products has created a favorable environment for the development of overweight. Consumers, however, are becoming more aware of what they eat and looking for low-energy products but which are palatable. Creating new formulations is not an easy task, considering that food perception is the result of multiple sensory modalities, including visual, taste, olfactory, and somatosensory inputs [4]. Some studies have been conducted on sensory interactions between taste and odor [5,6] although these mechanisms have not been considered in relation to the nutritional status of subjects. Our research group recently conducted studies aimed at the evaluation of: taste sensitivity, in normal-weight (NW) and obese (OB) subjects and multisensory interactions and liking in model foods according to nutritional status. MATERIALS AND METHODS Taste sensitivity was assessed in 51 OB (recruited from ICANS) and 52 NW subjects by evaluating the taste thresholds for the basic tastes and fat stimulus (3-AFC, ASTM E679-04) and the fungiform papillae number (FP) [7]. 51 OB (recruited from Istituto Auxologico Italiano) and 41 NW women evaluated liking and intensity of sensory properties of custard desserts prepared by adding different concentrations of two flavoring compounds (either vanilla or butter) or a thickener (xanthan gum) to a standard formulation. Three terns of custards desserts were obtained by adding increasing concentrations of vanilla (V1, V2) or butter aroma (B1, B2) or a thickening agent (xanthan, XG1, XG2) to a standard formulation (ST). RESULTS AND DISCUSSION The results showed that OB subjects differed in terms of taste sensitivity from NW subjects. More specifically, OB subjects involved were less sensitive to taste stimuli compared to the lean subjects (sweet p<0.001; savory p<0.01; bitter p<0.01; fat p<0.001; sour p<0.05; PF p<0.001).These differences may lead subjects with higher BMI to prefer foods rich, for example, in sugar and fat in order to compensate their reduced sensitivity [8]. Moreover, the multisensory interactions (odor-taste-texture) occurred differently in relation to BMI. Indeed, a model food (custard dessert) modified with aromas and thickener agents produced strongest sensory interactions (odor-taste, odor-flavor and odor-texture) in subjects with higher BMI compared to the control group. The addition of a stimulus signaling high-calorie products, such as butter aroma, modified the perception of different sensory characteristics in a more effective way in obese subjects compared to the normal-weight. For example, obese subjects perceived the modified samples with butter aroma, as significantly sweater (p <0.01) and creamier (p <0.05) than the standard formulation. Significant differences (p<0.05) in liking scores were found in the samples modified with the addition of butter aroma, with higher scores provided by OB compared to NW women. In both groups liking decreased with increasing concentration of thickener agent (p<0.05). No differences in liking scores were found considering samples with different amount of vanilla aroma [9]. CONCLUSIONS It is evident that investigate the phenomenon of obesity applying an innovative sensory approach is interesting in order to better understand and stem the complex issue of overeating. How the mechanism of brain integration occurs in subjects with different nutritional status might be taken into account in order to develop new food products with a reduced caloric intake but which are still satisfying for the consumer. ACKNOWLEDGMENTS We would like to thank the team at the Department of Medical Sciences and Rehabilitation, IRCCS Istituto Auxologico Italiano (Milan, Italy) and the International Center for the Assessment of Nutritional Status (ICANS, Università degli Studi di Milano, Italy), who provided help in recruiting obese subjects. REFERENCES [1] De Graaf, C. (2005). D. Mela (Ed.), Food, diet and obesity, Wood head Publishing Limited, Cambridge, England, pp 137-159. [2]Simchen, U., et al. (2006). Eur J Clin Nutr. 60:698–705. [3]Bertoli, S., et al. (2014). World J Diabetes. 5(5): 717-723. [4]Small, D.M. & Prescott, J. (2005). Exp. Brain Res, 166, 345–357. [5]Lavin, J.G. & Lawless, H.T. (1998). Food Qual Prefer, 9(4), 283–289. [6]Maga, J.A. (1974). Chem Senses, 1(1),115-119. [7]Nachtsheim, R, & Schlich, E, (2013). Food Qual Prefer. 29, 137–145. [8]Proserpio, C., et al. (2016a). Chem Senses, 41, 169–176. [9]Proserpio, C., et al. (2016b). Appetite, 100, 203-209.