Improving donor human milk by novel processing technologies

Human milk (HM) reduces the risk of necrotizing enterocolitis in high–risk infants and is essential for optimal infant growth. When mother’s own milk is unavailable, donor human milk (DHM) represents the best alternative. Human milk banks subject DHM to holder pasteurization (HoP) to ensure its safety and although most nutritional components remain unaffected, many bioactive components are significantly decreased. For this reason, this thesis investigated the impact of thermal and non–thermal alternatives to HoP, on DHM safety and functionality. First, the analytical techniques that could be used for such analyses are described (chapter 2). The large variation in European milk banking practices is discussed in chapter 3, specifically in pasteurization practices, storage and milk screening. When the thermal treatment was optimized (chapter 4), immunoglobulin A (IgA) and lysozyme levels and functionality were comparable to that of untreated DHM. However, lactoferrin and bile salt–stimulated lipase (BSSL) were significantly affected. High–pressure processing (HPP), ultraviolet–C irradiation (UV–C) and thermoultrasonication preserved IgA lactoferrin, lysozyme and BSSL better than HoP, with less intense HPP and UV–C treatments preserving these proteins in comparable levels to untreated DHM (chapter 5). These methods also preserved DHM insulin better than HoP (chapter 6). HPP preserved HM’s neutralizing capacity against SARS–CoV–2 (chapter 7), a function eliminated after HoP. HoP destroyed HM’s procoagulant activity, but UV–C preserved it (chapter 8). In summary, non–thermal methods such as HPP and UV–C may be regarded as the most promising alternatives to HoP.