New Approach to Investigate the Quality of Parmigiano Reggiano Cheese: Multi-Scale Virtualization of the Structure and Analysis of Fundamental Rheological Properties

The aim of this PhD research project is to investigate the quality of Parmigiano Reggiano cheese (PR) through an innovative approach, which is based on virtualization and analysis of the physical structure in large dimensional scale as well as on the determination of fundamental rheological properties. New physical markers were proposed as objective descriptors of the so called “frattura a scaglie”, a quality requirement of the official production disciplinary as well as for better understanding of the role of cheese making and ripening processes on the final quality To achieve this target we will investigate the cause-effect relationships between structure, mechanical properties and some key variables of the making process. The quality of Parmigiano Reggiano (PR) cheese is regulated by an official production disciplinary of origin (PDO) which imposes accomplishment of requirements both about making technology and product properties. It is widely known among producers and widely documented in the scientific literature that the sensory quality of the PR cheese is closely related to both the surface and inner structure, which originates during milk clotting operation units evolving throughout the entire ripening process due to the continuous mass transport phenomena between the cheese and environment. An expert panel evaluates the way the cheese propagates sound and mechanical fracture throughout own bulk under non standardized empirical test conditions, in order to classify the PR cheeses into four commercial categories. A plethora of subjective and experimental conditions, the latter including sample size and geometry, the rate and temperature dependence of stress-related deformation (Imbeni et al., 2013) or relaxation times distribution under mechanical solicitations of semi-hard cheeses (Del Nobile et al., 2007) may affect both the repeatability and accuracy of sensory analysis of the cheese mechanical behavior. Moreover, the high variability of the milk composition, the prohibition to standardize it as well as the yet artisanal and empirical management of technological variables in cheese making contribute to the high variability in the final quality as well as into the classification of the cheese. The available literature shows that PR cheese has been investigated extensively for cheese composition and biochemical markers, but very little works have been successfully carried out to get useful theoretical and experimental information about the inner structure (Delphine et al., 2013, Tansman et al., 2013), rheological properties. Empirical approaches have been followed aiming to investigate PR cheese rheology (Noel et al., 1996) and relationships between technological and ripening conditions (Mucchetti et al., 2014; Foeding et al., 2003, Noel et al., 1996). In this research work PR cheese will be analyzed on a multi-scale length by coupling non destructive imaging to fundamental rheological techniques under the perspective to get new basic insight about the inner structure, on how its related both to the technological and ripening conditions. A feasibility study will be also conducted for evaluating the development of a micro-structured model able to predict the cheese rheological properties and behavior under controlled conditions.