New perspectives in HTST pasteurization of donated human milk

According to the existing literature (Peila et al., 2016, Picaud et al., 2017, Klotz et al., 2017), High-Temperature Short-Time (HTST) pasteurization of human milk (HM) seems to be a promising alternative to Holder pasteurization in ensuring HM microbiological safety, and in better preserving the HM antioxidant potential, lactoferrin content and structure, B and C vitamins, and some cytokines. In the past, the application of HTST to HM has been performed exclusively at a laboratory scale. Some authors used laboratory equipment, consisting of stainless steel tubing systems submerged in thermostated water baths, through which HM was pumped; others injected milk through a sterile water stream in a platetype industrial heat exchanger; some research studies were conducted by directly heating and rotating small aliquots of milk, to simulate the typical thin-layering of dairy industry HTST devices. Several studies involved simply heating small aliquots of HM in a bulk process. All the reported processes were substantially different from industrial HTST processes. A new small-scale continuous-flow 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 (Cavallarin et al., 2016). The new HTST apparatus can effectively pasteurize human milk with a better retention of sIgAs content and BSSL activity and it complies to human milk banking safety requirements