A technological and physiological integrated approach for appetite control : from identification of novel biomarkers to development of new functional ingredients

A technological and physiological integrated approach for appetite control. From identification of novel biomarkers to development of new functional ingredients. Human dietary behaviour is driven by homeostatic, hedonic and environmental factors. Foods can influence these factors throughout extrinsic (marketing suggestions, portion sizes, form) and intrinsic characteristics (taste, flavour, smell, texture). In turn biochemical response and psychological traits influenced food taste, flavour, smell and texture perception determining the hedonic value of a meal. This interplay between the food and the subjective psychophysiological response determine the control of energy intake, therefore must be considered in developing food for appetite control. In the present thesis four human studies are described. Of these two were conducted to investigate the role of the saliva and the endocannabinoids system in the food preference and liking during the cephalic phase of digestion. We found out that salivary enzymes activity are influenced by nutritional status, food preference and food habits. Moreover, food palatability influenced some plasma endocannabinoid and N-acylethanolamine concentrations during the cephalic phase response and indicated that 2-arachidonoylglycerol and pancreatic polypeptide can be used as biomarkers of food liking in humans. These findings can have interesting implications in designing foods for appetite control: salivary enzymatic activity must be considered because it influence taste and texture perception and consequently food choice; the measure of 2-arachidonoylglycerol can offer the possibility to merge the sensory and biochemical approach to compare the satiating and rewarding capacity of foods. The other two studies investigated the potential satiating effect on the short term energy intake of specific food ingredients. As previous in animal studies shown, we demonstrated (chapter 4) that also in humans the circulating oleoylethanolamide levels can be modulated by the fatty acid composition of a meal and this can influence the short-term energy intake. Therefore, we highlighted the anorexigenic effect of the oleoylethanolamide that can be a target of specific food ingredients. In the study described in the chapter 5, we aimed in assessing the appetite control capability of bitter compounds. The ingredient was microencapsulated with the double aim to avoid the (not palatable) taste perception in the mouth and to deliver the compounds directly in the gastrointestinal tract and target the enteroendocrine bitter taste receptors. We showed that microencapsulated bitter compounds are effective to reduce daily energy intakes in humans. This study demonstrated that sense the taste receptors directly in the gastrointestinal tract may be a valid way to trigger satiety and control appetite. The general conclusions of the present thesis are that a fine design of ingredients for appetite control is necessary to develop novel foods for appetite control that has to take in account from one side the hedonic value from the other side the functionality.