## 2 The NMR-Based Metabolomics in Food Science and the Foodomics Approach
Target analysis, or metabolic profiling, is the identification and quantification of given and predefined metabolites [26]. It can be a specific metabolite or a selected number of metabolites. In the first case, a selective extraction is necessary before the NMR analysis to concentrate the selected metabolite. The latter case is used when the attention is focused on the specific role of a selected metabolic pathway; this approach is called metabolic profiling [27]. The pattern analysis is metabolic profiling obtained by identifying and quantifying all metabolites. This operation is led by using specific software, such as Chenomx [28; 29], and it is called'metabolomics.' On the other hand, metabolic profiling is used when sample classification without quantification of individual-specific metabolites is required [27]. In this case, the NMR spectrum becomes a fingerprint of the product, and all the NMR resonances/signals are measured without any identification [30], and it is called 'fingerprinting'. Due to the above-all-mentioned characteristics, it appears clear why in the last 15 years academic researchers have employed NMR-based metabolomics in food science more and more. With this technology, academics meet the consumers' requests in one shot: a green approach that both pays attention to the environment in sample preparation and can assess and guarantee the quality of foodstuff. It is not a coincidence that with the opening of the food markets at a worldwide level, the number of research papers on the evaluation of food quality by using an NMR-metabolomics approach increased. [PERSON] and [PERSON] [31] explain that the globalization phenomenon changes the definition of  
Figure 2: An outline of the four most important omics fields, ranging from genomics to metabolomics. food quality that have to include also other aspects like geographical origin, sophisticated frauds, and adulteration practices, etc. The expansion of the food quality concept is also determined nowadays by the introduction on the market of new foods formulated to be much more sustainable and green [32]. These innovative foods are designed considering unconventional sources of nutrients, such as insects [33; 34; 35], for example, but also converting waste products into second-life products [36; 37; 38]. For this reason, consumers have to be reassured about food safety and from a nutritional value point of view. As these new aspects overcome the official analytical determination focused on specific compounds investigation, the role of metabolomics in this new quality assessment has become very important [31]. The importance is proved by the tremendous number of papers dealing with metabolomics and NMR that appear in the bibliography. Among them, geographical origin plays a key role as food quality is strongly affected by the particular conditions of production areas, which give unrepeatable organoleptic and nutritional properties to agricultural food products [39]. Extensive studies have been performed on several different foods to find out biomarkers able to classify them concerning their geographic origin: extra virgin olive oil (EVOO) [40; 41; 42; 43], cheese [44; 45; 46], tomato [47; 48; 49], saffron [50; 51], fruits and vegetables [52; 53; 54; 55; 56], honey [57; 58; 59; 60] and wine [61; 62; 63; 64; 65], etc. Food frauds and adulteration have been largely taken in consideration in NMR-based metabolomics studies as well [66; 67; 68; 69; 70; 71; 72; 73; 74; 75]. The application of NMR-based metabolomics in a food quality context can be included in the so-called foodomics, and we can talk about NMR-based foodomics. The first definition of this omics approach appeared in 2009 by [PERSON] [76], and it put attention on the investigation of all the possible connections among food, diet, and the individual, including health and ill impact [16]. These connections are included in the suffix \"omics\", which comes from the Latin word \"omne\" and it means everything, totality, wholeness, and entirety [77].