## 1 Introduction  
Parmigiano Reggiano (PR) cheese is one of the oldest traditional cheeses produced in Europe (XII century) and it is still one of the most esteemed Protected Designation of Origin (PDO) Italian cheeses [1]. PR Cheese originates in Northern Italy, in the countryside area that touches five different cities (Parma, Reggio Emilia, Modena, and portions of the provinces of Mantua and Bologna). PR is a hard curd cheese obtained through a peculiar technology based on the use of unheated raw cow's milk. For a cheese to gain the Protected Designation of Origin (PDO) title, the bond with its own traditional characteristics is dramatically important because, as stated in the Council Regulation European Union (EC) No. 510, 2006 on the protection of geographical indications and designations of origin for agricultural products and foodstuffs, the link between \"authentic and unvarying local methods\" and \"tradition\" is essential. This indication implies that PDO products also have distinctive sensory characteristics, which are strongly connected to the traditional production methods, thus guaranteeing the consumer a sensory quality that lasts over time. The PR cheese Consortium (CFPR), located in the PR production area (Italy), is the institutional system that covers all cheese dairy factories and controls cheese production in terms of cow feeding, cheese manufacturing, and ripening processes. CFPR production guidelines are based on the secular experience, the regional habits and practices, and the technological innovations that could leave the uniqueness of the product unchanged (EC, 510/2006) [2]. Research on aroma chemistry have attracted a lot of attention, as well. The grating operation must take place in the defined geographical area of cheese production and packaging must start immediately, without any processing or addition of substances that could change its preservation and its original organoleptic characteristics. Grated cheese has to be characterized by the absence of additives, no more than 18% crust in its moisture, a non-crumbly aspect and homogeneous particles with less than 0.5 mm diameter, not exceeding 25% (Decreto del Presidente del Consiglio dei ministri della Repubblica Italiana, D.P.C.M., 4/11/1991). Therefore, it is essential to find a method to determine the rind and pulp percentage of grated PR cheese, based not only on the classical expensive and slow chemical techniques. Classical techniques like High Performance Liquid Chromatography (HPLC), GC-MS, or microbiological analysis need a few hours to achieve results. The possibility of detecting the addition of extra rind to grated cheese (addition made with a large range of different seasoned cheeses) and the ripening time of PR cheese has been studied by means of destructive chemical methods. The fight against counterfeiting is a priority for PDO of protection. The globalization of markets has been providing both new opportunities and risks: the possibility to package the product worldwide makes carrying out document checks increasingly difficult and this is why the Consortium is working to change the rules of production of Parmigiano Reggiano requiring conditioning in the area, and developing sophisticated solutions for product traceability. The aim of this work is to provide a rapid, non-destructive, and compact device able to determine the authenticity of PR and the respect of its regulations (grated percentage). Aroma (fingerprint) is one of the most significant food parameters from a sensory point of view and it may offer information about safety and quality, sometimes being an indicator for processing mistakes, as well [3]. The use of an S3 device to determine the specific volatile organic compounds (VOCs) of grated PR is a promising approach offering, at the same time, a simpler, faster, and easier to handle (no specialized technicians are required) solution if compared to other analytical techniques (GC-MS, HPLC). From a commercial point-of-view, low cost and reduced power consumption are fundamental features.