Pasteurization of human milk by a benchtop High-Temperature Short-Time device

Abstract

A new small-scale continuous-flow High-Temperature Short-Time (HTST) pasteurizer has been designed for treating human milk. The efficacy of the new HTST device was assessed on inoculated Listeria monocytogenes, Staphylococcus aureus and Chronobacter sakazakii, as well as on raw human milk bacteria. The milk biochemical quality after HTST pasteurization was assessed in comparison to a standard Holder pasteurization, by determining the secretory IgAs (sIgAs) content, the protein profile, lysozyme and the Bile Salt Stimulated Lipase (BSSL) activities. No pathogen or bacterial growth was detected after HTST pasteurization with the new instrument. Changes in the protein profile were observed in the milk pasteurized according to both processes. The sIgAs content and BSSL activity were significantly higher in the milk pasteurized with the new device than in the same milk treated by the standard Holder pasteurization. In conclusion, the new HTST apparatus: (i) can effectively pasteurize human milk with a better retention of sIgAs content and BSSL activity; (ii) comply to human milk banking safety requirements. Currently, 210 active human milk banks are located in Europe (and 17 more are planned). The majority of the European banks still use Holder-based pasteurizers, which, despite efficacy in ensuring microbiological safety, are known to reduce/disrupt important nutritional and non-nutritional biological factors. Although already widely established in food industry, the advantages of HTST technology were tested only at small laboratory scale for human milk. The device tested in the present research was specifically designed to provide human milk banks with the technology they need to ensure a safe and lower-impact pasteurization process, that is suitable for processing different volumes of donations. The device can pasteurize up to 10 L of milk per hour, with a minimum volume of 100 mL. The system is designed to be cleaned-in-place (CIP) after each pasteurization run and sanitized immediately prior to the next use, being thus more suitable for treating pools of milk from different donors than milk from single donations. Italian and EU patents have been filed for the device, within a partnership between public research institutions, stakeholders (Italian association of donor milk banks), and a private company in the sector of dairy processing equipment. The device has achieved a Technology Readiness Level (TRL) 6 (Prototype demonstration in a relevant environment). The cost of the new device will be comparable to that of a typical human milk Holder pasteurizer.