# Natural Appetite Control: Consumer Perception of Food-Based Appetite Regulating Aromas
## 1 Introduction  
In light of recent and up-coming changes in societies, health and demographical structure, appetite control is one of the crucial factors affecting the well-being. Unfortunately, according to the World Health Organisation (WHO), the numbers of overweight (BMI \(\geq\) 25) and obese (BMI \(\geq\) 30) individuals are constantly growing. In 2016, those numbers have reached 1.9 billion (38% of the worldwide population) and 650 million (13% of the worldwide population), respectively [1]. On the other hand, the number of elderly people (\(\geq\)60 years old) in 2020 reached 1.4 billion [2]. Among this figure of elderly people, approximately 25-30% will be affected with anorexia of aging, which may be caused by appetite loss [3]. Therefore, both mentioned groups demonstrate their individual and characteristic appetite disorders.  
Hunger and appetite are closely related terms, which are often confused. While hunger is an organism response for its homeostasis distraction (e.g., calories deficit), appetite, also named hedonic hunger, is a psychological need for food consumption, thus often a food craving stimulated by a constant food-fulfilled environment, even without an organism-calories deficient state [4; 5]. The problem of craving may be caused by a disturbed activityof AGPR neurones, which are responsible for signalling the calories needed, and what activity can be suppressed by food delivery. However, in addition, sensory stimulus related with food intake should be able to induce a similar suppression of neurone activity [6].  
Sensory stimulants, which may reduce the activity of APGR neurones, are food, texture, taste, visual aspects and smell, among which, the last two could be used without actual food intake, which is crucial for both appetite stimulation and reduction [7; 8]. Of course, the presence of food in front of the consumer has the predominant role in appetite changes, however, smell may be underrated regarding public health, in light of malnutrition or, in the contrary, the epidemic of overweight and obesity [9]. Recent studies on food odours, which are representative of high carbohydrate or protein or lipid content, showed that it is possible to stimulate an odour-specific (protein-related) appetite, however, overall food intake was not significantly affected [10]. Furthermore, it has been well documented that the odour of particular foods, such as sweet and savoury foods, may increase the appetite for food with a similar taste and/or calorie density, regardless of hunger levels [11]. Meanwhile, by in-depth food chemical analysis it was also determined that some food aromas, namely curry, nutmeg, or vanilla, due to the presence of particular chemical structures within their volatile organic compounds, may possess appetite-enhancing effects, which were examined in a mice model [12; 13; 14]. These chemical structures are mainly phenylpropanoloid compounds, phenylpropanoloid compounds with carbonyl group on the aliphatic chain, and compounds containing the vanillyl group.  
Therefore, a study was designed to deeper explore the possible relations between the perception of food smell that enhances appetite or reduces appetite, and the actual volatile constituents of the food. For this purpose, the survey was carried out, dividing participants into two groups that both exhibit appetite dysfunctions--(i) overweight or obese individuals and (ii) elderly people (\(\geq\)60 years old). Thereafter, the survey results were used to select a group of food products and meals, which were subjected ti the analysis of volatile organic compounds emitted from the food by the HS-SPME Arrow-GC/MS technique. Finally, 26 appetite regulating prototypes were designed and subjected to the sensory panel assessment.