High-Temperature Short-Time Preserves Human Milk's Bioactive Proteins and Their Function Better Than Pasteurization Techniques With Long Processing Times.

Eva Kontopodi,Kasper Hettinga,Johannes B Van Goudoever,Ruurd M Van Elburg,Sjef Boeren,Bernd Stahl

doi:10.3389/fped.2021.798609

Abstract

Donor human milk is generally processed by holder pasteurization (HoP) at 62. 5°C for 30 min. This temperature-time combination is sufficient for eliminating pathogens in donor milk, but also negatively affects several bioactive milk components. Long heating up times may further affect the bioactive properties of pasteurized milk. High-Temperature-Short-Time (HTST), a treatment with shorter processing times (72°C for 15 sec), was investigated as a suitable alternative to HoP. In addition, pasteurization methods that follow the same temperature regime but with varying heating up times were compared. Human milk samples from four different donors were combined into one pool, which was then used to perform all analyses. The effects of these methods on the levels and functionality of immunoglobulin A, lactoferrin, lysozyme and bile salt-stimulated lipase, were evaluated with LC-MS/MS-based proteomics and activity assays, while the pasteurization efficacy was evaluated with an alkaline phosphatase test. HoP, a treatment with long processing times, times, caused the highest reduction in all proteins studied (reduced by 50–98%). Compounds such as lactoferrin and bile salt-stimulated lipase that are more sensitive to heat treatments were better retained with HTST, but their levels and functionality were still significantly lower than those of untreated donor milk (52 and 81% reduction of lactoferrin and bile salt-stimulated lipase activity, respectively). Our findings showed that a treatment with considerably shorter processing times, such as HTST, may reduce the thermal damage caused to the bioactive proteins compared to HoP, without affecting pasteurization efficacy. Since the vast majority of the donor human milk banks that are currently operating on a global level apply HoP to donor milk, our findings may provide relevant information for the optimization of donor milk processing.

Highlights

Tailored to each infant’s need, mother’s own milk represents the optimal source of neonatal nutrition
In order to assess the effect of the different methods on the functionality of the three major human milk (HM) antimicrobial proteins (IgA, LTF, LYZ), we evaluated the growth rate of two bacterial strains known to be inhibited by these proteins
The temperature profiles of the different treatments were broken down into three sections: the heating up time to the pasteurization temperature, the time that donor human milk (DHM) was held at this temperature, and the time required for DHM to cool down to 4◦C (Table 1)

Summary

Introduction

Tailored to each infant’s need, mother’s own milk represents the optimal source of neonatal nutrition. The unique composition of human milk (HM) promotes healthy infant development and growth, while the numerous bioactive factors it contains, protect infants against infections and various diseases [1, 2]. LTF, amongst others, limits the availability of the iron required for the growth of iron-dependent pathogens, LYZ disrupts cell walls in gram-positive bacteria, and secretory IgA is generally considered as the main antibody system in HM. Synergistic effects of these proteins have been reported [3,4,5]. For premature infants, when mother’s own milk is not available, donor human milk (DHM) represents the best alternative form of nutrition. DHM should be provided though established human milk banks (HMBs) that can ensure its safety [7]

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