## 1 Introduction  
The analysis of the volatile fraction of food is essential for understanding, planning, and improving the sensory characteristics of new products [1]. The aroma of fruits and vegetables strictly depends on their chemical composition, as well as on any possible constitutive variation [2, 3]. Furthermore, it is determined by unique combinations of Volatile Organic Compounds (VOCs) with different physicochemical properties and perceptual thresholds [4]. These VOCs confer specific quality characteristics and represent valuable and interesting sensory parameters, particularly for the food industry. The aroma of a food product is directly related to its acceptability by consumers, nutritional and qualitative characteristics, health, and safety [3]. The measurement and identification of VOCs, in the specific case of fruits, allow to highlight any differences between different cultivars of the same species [5]. These variations are linked to geographical origin, cultivation site, production methods, harvesting technologies, degree of ripeness, and aging [2, 3, 6]. Monitoring VOCs over time allows the achievement of different goals. For example, it is possible to establish authenticity and traceability of food products. These controls are more effective when targeting specific molecules that act as unique quality markers. Some analytes may develop over time, which reflects the age of the product. In addition, they could result from the manipulations to which the material is subjected (i.e., prolonged thermal stress, sterilization, cooking, drying, etc.). These studies are important because, among the countless VOCs, some are not particularly desirable because they impart unpleasant aromas (the \"off-flavors\"), compromising the acceptability of the product by the final consumers [7, 8, 9, 10]. The VOC fraction also persists in the dietary fiber (DF) that can be obtained from fruits or vegetables. Consumption of DF in human nutrition plays a functional role in maintaining good health. Therefore, nutritionists have largely encouraged an increase in its consumption [11, 12] as the modern diet of Western countries is particularly devoid of it. In addition, animals also benefit from a high-fiber diet [13]. According to the Food and Agriculture Organization of the United Nations (FAO), one of the Sustainable Development Goals is the transformation and conversion of poor and waste materials into value-added resources. A significant amount of food is wasted directly in the field, and approximately one-third of the agri-products for food supply are wasted [14]. The recovery of these materials allows their conversion into new opportunities to obtain functional foods. In fact, agri-food waste is often rich in nutrients such as dietary fibers, polyphenols, vitamins, and minerals [15]. The recovery of this edible waste perfectly follows the circular economy principles, aimed at achieving a \"zero-waste society\" [16]. In addition, it can help mitigate the low nutrient intake that is typical of modern diets. Pursuing our previous works regarding the recovery of dietary fiber from agri-food waste [5, 17, 18], in this study, we obtained and examined the whole dietary fiber (WDF) from watermelon pomace. Pomace is the pulp residue remaining after the fruit has been crushed to extract its juice. Watermelon (_Cirullus Lantus_ L.), belonging to the Cucurbitaceae family, is widely consumed and is the second most common fruit crop worldwide [19]. According to statistics from the Food and Agriculture Organization, global watermelon production reached approximately 104 million tons in 2019 [20]. The Italian Institute of Statistics (ISTAT) estimated that 8.5% of the total production was not harvested during the 2020 cultivation cycle, corresponding to approximately 55 Ktors/year [21]. These data are impressive considering the worldwide production of watermelons.