Statistical, chemometric and computational approaches to improve quality and increase market share of fresh and long-ripened Italian cheeses

Globalization of food markets and the increasing demand for some highly perishable and traditional Italian cheeses, forced the dairy sector to investigate in new methods to improve export and/or to control compliance with PDO regulations or internal quality schemes. Cheese quality characteristics should be improved by studying the strong relation between product’s properties and process parameters and efficiency, in order to understand the critical phenomena that are involved in food processing. In this context, chemometric and computational tools are statistical approaches that can be applied to study these complex relations, in particular when many process parameters and product’s characteristics are evaluated at the same time, or to model food processing. Despite its high energy consumption, freezing of fresh dairy products can be a sustainable solution for supply chains: because of the improved storability and convenience, frozen products can be characterized by a lower impact on the carbon footprint if compared to fresh, refrigerated product; cconsidering long-distance markets, freezing can help to lower the costs of transport, by preferring the maritime transport instead of air transport, and can help to decrease waste by decreasing the amount of expired products to be withdrawn from the market. The feasability of high moisture cheese freezing and frozen storage can be valuable, but attention should be payed about process efficiency in terms of energetic costs, and product’s sensitivity in relation with the freezing process and frozen storage. Concerning dairy products regulated by European Protected Designation of Origin (PDO), dairies need fast and reliable methods to control their processes and to verify compliance with both legal limits or more severe internal quality programs. In the case of Parmigiano-Reggiano (P-R) cheese, grated P-R cheese accounted for 13.5% of the overall market of P-R cheese in 2017 and this percentage continuously increased in the last years. Grated P-R PDO cheese must comply with the maximum percentage of rind and particles having a diameter lower than 0.5 mm (<18% w/w and <25%, respectively), because an excessive amount of rind can have a negative impact on the sensory characteristics and product’s quality. The present thesis enabled to improve the knowledge about factors and phenomena that rule the behavior and the modification of fresh and long ripened cheeses during freezing and grating processes. Mathematical models were created to study Mozzarella cheese freezing process; thanks to a developed photogrammetric technique, it was possible to accurately reproduce Mozzarella cheese non-regular geometry and to accurately estimate freezing time and temperature profiles. Models highlighted the presence of temperature-surface differences related to the irregular geometry of the cheese that can also cause modification of the characteristics in the external layer. Moreover, freezing times were found to be strongly influenced by cheese shape variations. Mathematical freezing models can be valuable in industrial applications to predict freezing times and can be used to control and improve efficiency of Mozzarella cheese freezing process. Different freezing and thawing rates, that were experimentally modulated as a function of applied air temperature and velocity, did not cause significant modifications of Mozzarella cheese characteristics, as the freezing time was sufficiently short. On the contrary, the presence of covering liquid during freezing and thawing processes caused an absorption of water of Mozzarella cheese, that was found to be more viscous-like and humid than the fresh-one. Thus, freezing in the presence of covering liquid was a less suitable method to freeze Mozzarella cheese. Frozen storage of Mozzarella cheese slowed down but did not stop proteolytic reactions that showed a higher rate after thawing; oxidative reactions were also present. Moreover, frozen-stored cheeses showed a modification of water status from a molecular and a mesoscopic point of view, as a consequence of casein degradation and conformational change, that caused protein’s dehydration. Milk quality and cheese composition should be accurately controlled in order to limit the presence of proteolytic and lipolytic enzymes in the cheese, and to obtain good results after prolonged frozen storage. Moreover, a shorter shelf life period should be proposed for frozen-thawed cheese than the fresh one. Concerning grated P-R cheese, the grating behavior of different cheeses was found to be related to the textural properties of different zones of the wheel; in particular rind’s particles showed different particle size properties and in general were characterized by lower dimensions if compared to particles of the inner part of the cheese. According to these differences, it was possible to successfully predict particle size and rind percentage variations thanks to NIRs and IA measurements. These techniques can be successfully applied by dairies as internal quality control measurements to comply with both PDO regulation and quality programs.