## 1 Introduction  
The pigmented oranges belonging to the varieties \"Tarocco\", \"Sanguinello\", and \"Moro\", are currently processed by the Italian citrus juice industry, producing a pigmented (blood) orange juice which is very peculiar in respect of its sensory and nutritional properties. The blood orange juice is an acidic aqueous solution (pH-3.3) with a cloudy appearance due to the presence of pectins in suspension in the colloidal state, with a bright red color, a pleasant sweet-acid flavor, and a characteristic fresh and delicate aroma [1]. The soluble components are represented in higher concentrations by simple sugars (sucrose, glucose, and fructose) and organic acids (citric, malic, and isocitric), while various bioactivecompounds such as hydroxycinnamic acids, flavanone glycosides, and vitamin C are well represented, playing a very relevant role in the biochemistry of the fruit and giving the juice a high nutritional value [2]. Specifically, blood orange juice is characterized by the presence of water-soluble pigments belonging to the anthocyanin class, which are responsible for its red brilliant color, being also responsible for the higher healthy value of blood orange juice compared to that reported for blond or common orange juice [3,4]. Once blood orange juice is extracted, after pulp reduction processes through refining, a stabilization phase is necessary for the prevention of chemical, physical, and microbiological alterations. Indeed, the NFC (not from concentrate) juice can undergo enzymatic alterations, such as the loss of the characteristic turbidity, or the incidence of oxidative and microbiologically detrimental phenomena, such as the development of spoilage microorganisms responsible for unwanted fermentation processes. At present, HTST (High Temperature Short Time) thermal pasteurization is currently employed for the stabilization of citrus juices as it is effective in counteracting the onset of enzymatic and biological degradation alterations. This pasteurization is generally carried out in heat exchangers in which the heating fluid, consisting of hot water or circulating steam, flows in countercurrent mode with respect to the flow of the juice to be pasteurized. In this way, the juice is brought to temperatures between 80 and 95 \({}^{\circ}\)C for 15-60 s. At the end of the thermal stabilization, the juice is cooled and sent for ultra-clean packaging in multilayer containers, PET, or glass bottles or, alternatively, used for concentration [5]. The pasteurized juice is marketed in the refrigerated supply chain (T = 4 \({}^{\circ}\)C) with a shelf-life of approximately 45-60 days or, alternatively, sent to concentration and further stored in 240 kg drums as frozen concentrated orange juice. It must be also noted that, in Italy, almost all citrus companies carry out a re-pasteurization heat treatment when the stabilized frozen blood orange juice is thawed to be sent to both national and international client companies. This re-pasteurization has the main aim of providing customers with a juice that is certainly microbiologically \"cleaner\" and therefore \"safer\", but it causes further thermal damage to the juice. Nonetheless, it has been widely demonstrated that thermal pasteurization negatively affects the intrinsic quality of the juice, specifically with respect to its nutritional and sensory value [6]. Indeed, it is known that sugars can react with some free amino acids contained in the juice according to the Maillard reaction, generating reaction products responsible for the non-enzymatic browning of the juice. Furthermore, sugary substances can also undergo caramelization. Other non-enzymatic browning can also take place with a color impact, including browning from ascorbic acid and the degradation and/or polymerization of the pigments present in the juice [7]. Finally, significant reductions in highly thermolabile water-soluble vitamins levels have also been highlighted [8].