animals Article Optimization of UV-C Processing of Donkey Milk: An Alternative to Pasteurization? Photis Papademas * , Panagiotis Mousikos and Maria Aspri   Citation: Papademas, P.; Mousikos, P.; Aspri, M. Optimization of UV-C Processing of Donkey Milk: An Alternative to Pasteurization? Animals 2021, 11, 42. https://doi.org/ 10.3390/ani11010042 Received: 16 October 2020 Accepted: 17 December 2020 Published: 28 December 2020 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2020 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). Dairy Science and Technology, Department of Agricultural Sciences Biotechnology and Food Science, Cyprus University of Technology, 3036 Limassol, Cyprus; panagiotis.mousikos@cut.ac.cy (P.M.); maria.aspri@cut.ac.cy (M.A.) * Correspondence: photis.papademas@cut.ac.cy Simple Summary: Donkey milk has received much interest lately due to its chemical composition, which is very close to human milk as well as to its unique functional properties (antibacterial, antioxidant, immunomodulatory, and antitumor activities). Furthermore, donkey milk is considered a valid alternative milk for infants and adults suffering from cow milk protein allergy. However, it is recommended by pediatricians and clinicians that raw donkey milk must be thermally processed to render it safe for sensitive population (i.e., infants and immunocompromised). On the other hand, thermal processing is known to reduce the bioactivity of milk. Consequently, the objective of this study is to determine the feasibility of the UV-C system to inactivate or reduce foodborne pathogens in raw donkey milk in order to produce a safe, non-thermally processed donkey milk that can be consumed by special population groups (infants, elderly, immunocompromised). Results obtained from this study indicate that UV-C has the potential to be used as a non-thermal treatment to reduce food borne pathogens present in raw donkey milk. Abstract: The effect of UV-C light technology on the inactivation of six foodborne pathogens in- oculated in raw donkey milk was evaluated. Fresh raw donkey milk was artificially inoculated with the following foodborne pathogens—L. inoccua (NCTC 11288), S. aureus (NCTC 6571), B. cereus (NCTC 7464), Cronobacter sakazakii (NCTC 11467), E. coli (NCTC 9001), Salmonella enteritidis (NCTC 6676)—and then treated with UV-C doses of up to 1300 J/L. L. innocua was the most UV-C-resistant of the bacteria tested, requiring 1100 J/L for complete inactivation, while the rest of the bacteria tested was destructed in the range of 200–600 J/L. Results obtained from this study indicate that UV-C light technology has the potential to be used as a non-thermal processing method for the reduction of spoilage bacteria and foodborne pathogens that can be present in raw donkey milk. Keywords: donkey milk; UV-C technology; non-thermal methods; microbial inactivation; milk pathogens 1. Introduction In recent years, there has been a growing interest for donkey milk production and commercialization due to its similar composition with human milk, making it ideal for consumption by sensitive population groups such as infants with cow milk protein allergy (CMPA), the immunocompromised, and the elderly [1]. According to the literature, raw donkey milk has a low total bacterial count; nevertheless, the presence of foodborne pathogens such as E. coli 0157, S. aureus, Campylobacter spp., and Cronobacter sakazaki was also detected [2–5]. Therefore, raw donkey milk is subjected to thermal pasteurization in order to ensure its microbiological safety and to comply with the European Community Regulation 853/2004. However, the method has many drawbacks such as high energy cost, and it may influence protein denaturation, deterioration of the technological properties of milk (e.g., prolong enzymatic milk protein coagulation) and loss of nutrients, which is associated with flavor degradation. Thus, there is an interest for alternative methods that Animals 2021, 11, 42. https://doi.org/10.3390/ani11010042 https://www.mdpi.com/journal/animals