Can high pressure processing (HPP) and ultraviolet-C irradiation (UV-C) treatment preserve donor milk bioactive protein structure and function better than holder pasteurization?

Human milk bioactive proteins are degraded during commonly used Holder pasteurization of donor milk. Alternative processing techniques that ensure biosafety while preserving bioactive proteins are needed, particularly for at-risk preterm infants. High pressure processing (HPP) and ultraviolet-C irradiation (UV-C) treatment are known to preserve a few bioactive milk proteins, but no systematic research has identified the minimum processing parameters and their effects on the entire array of milk proteins’ structure and function. There is a critical need to perform this research. Our long-term goal is to optimize feeding practices for preterm infants to improve their health outcomes. The objectives of this research are to identify the minimum HPP and UV-C treatment conditions that achieve equivalent microbiological safety to Holder pasteurization while optimally preserving bioactive protein structure and function. Our central hypothesis is that minimal HPP and UV-C treatment conditions will better preserve donor milk bioactive proteins’ structure and function compared with Holder pasteurization. Our hypothesis is based on our work and that of others indicating that HPP and UV- C treatment preserve some bioactive proteins. The rationale for this work is that it can lead to changes in donor milk processing that can improve bioactive protein retention and possibly infant health outcomes. Aim 1. Determine treatment conditions for HPP and UV-C pasteurization that maximize bioactive protein preservation compared with Holder pasteurization. Minimal conditions for HPP and UV-C biosafety will be determined and retention of bioactive milk proteins will be compared between unpasteurized, Holder pasteurized, HPP-treated and UV-C-treated donor milk via ELISA and proteomics analyses. Our working hypothesis is that minimal-condition HPP and UV-C-treated donor milk will have higher retention of bioactive proteins than Holder pasteurized donor milk. Aim 2. Identify the extent to which preserved bioactive proteins maintain their bioactivities after treatment with HPP and UV-C pasteurization. Bioactivity will be examined in whole milk and fractionated protein extracts of unpasteurized and Holder, HPP and UV-C pasteurized donor milk. Our working hypothesis is that HPP and UV-C treated donor milk proteins will retain a higher degree of their bioactivities compared with Holder pasteurized donor milk as determined by in vitro antibacterial, anti-adhesive, antiviral and immunomodulatory assays, lipase and protease assays. We expect to have determined the extent to which minimally processed HPP and UV-C treatment preserves bioactive proteins’ structure and function compared with Holder pasteurization. The positive impact of this research will be guidance for donor milk processors on how to optimally process donor milk for feeding preterm infants and information for clinicians on how to evaluate available donor milk sources. Changes in milk processing to better preserve bioactive milk proteins could improve preterm infant health outcomes.