Inadequate intake of vitamin D is a global health issue related to severe diseases, mainly involving subjects with dark skin pigmentation, patients affected by malnutrition, malabsorption syndromes, or obesity, and elderly people. Some foods fortified with vitamin D have been tested in vivo, but fortification strategies with a global outreach are still lacking. This review is focused on food fortification with vitamin D, with the aim to collect information on (a) formulation strategies; (b) stability during processing and storage; and (c) in vitro bioaccessibility. Approaches to add vitamin D to various foods were analyzed, including the use of free vitamin D, vitamin D loaded in simple and double nanoemulsions, liposomes, casein micelles, and protein nanocapsules. Numerous studies were reviewed to elucidate the impact of food technologies on vitamin D’s stability, and mechanisms that lead to degradation were identified—namely, acid-catalyzed isomerization, radical-induced oxidation, and photo-oxidation. There is, however, a lack of kinetic data that allow for the prediction of vitamin D’s stability under industrial processing conditions. The roles that lipids, proteins, fibers, and antioxidants play in vitamin bioaccessibility have been clarified in various studies, while future needs include the design of specific food matrices that simultaneously achieve a balance between the long-term stability, bioaccessibility and, ultimately, in vivo functionality of vitamin D.

Extending ripening of hard cheeses well beyond the traditional ripening period is becoming increasingly popular, although little is known about the actual evolution of their characteristics. The present work aimed at investigating selected traits of Parmigiano Reggiano cheese ripened for 12, 18, 24, 30, 40 and 50 months. Two cheeses per each ripening period were sampled. Although moisture constantly decreased and was close to 25% in 50-month cheeses, with a parallel increase in cheese hardness, several biochemical changes occurred involving the activity of both native and microbial enzymes. Capillary electrophoresis demonstrated degradation of α_s1- and β-casein, indicating residual activity of both chymosin and plasmin. Similarly, continuous release of free amino acids supported the activity of peptidases deriving from lysed bacterial cells. Volatile flavor compounds, such as short-chain fatty acids and some derived ketones, alcohols and esters, evaluated by gas chromatography with solid-phase micro-extraction, accumulated as well. Cheese microstructure was characterized by free fat trapped in irregularly shaped areas within a protein network, with native fat globules being no longer visible. This study showed for the first time that numerous biochemical and structural variations still occur in a hard cheese at up to 50 months of aging, proving that the ripening extension deserves to be highlighted to the consumer and may justify a premium price.