A New High Hydrostatic Pressure Process to Assure the Microbial Safety of Human Milk While Preserving the Biological Activity of Its Main Components

Abstract

Background: The main process used to pasteurize human milk is the low-temperature, long-time Holder method. More recently, the high-temperature, short-time method has been investigated. Both processes lead to the appropriate inactivation of vegetative bacterial forms but are ineffective against bacterial spores.Research Aims/Questions: We aimed to accomplish two main objectives: inactivation of all pathogens, including spores; and preservation of the activity of milk components.Design/Methods: Recently, a novel high-hydrostatic pressure process has been developed by HPBioTECH. Using the same raw human milk samples, we compared the effects of this method with those of the Holder method on vegetative and spore forms of pathogens and on bioactive components (lipase activity, immunoproteins).Results: Two main microbial strains were selected: Staphylococcus aureus (as a reference for vegetative forms) and Bacillus cereus (as a reference for spores). Use of the high-hydrostatic pressure process led to microbial decontamination of 6 log for both S. aureus and B. cereus. Additionally, the bioactivity of the main components of human milk was preserved, with activities of lipase, α-lactalbumin, casein, lysozyme, lactoferrin, and sIgA of ~80, 96–99, 98–100, 95–100, 93–97, and 63–64%, respectively.Conclusions: Use of this novel high-hydrostatic pressure process to generate microbiologically safe human milk may provide important benefits for preterm infants, including improved assimilation of human milk (leading increased weight gain) and improved resistance to infections. Because 10% of all human milk collected is contaminated by B. cereus, use of this method will also prevent waste.

Processing of Donor Human Milk: Update and Recommendations From the European Milk Bank Association (EMBA)

“…Under these conditions, the activity of certain important human milk biological components, such as lipase activity and immune proteins, is maintained. These results were obtained with a pressure of 350 MPa (40).…”

Innovative Techniques of Processing Human Milk to Preserve Key Components

“…HPP was shown to be even more effective in comparison to holder pasteurization in the elimination of inoculated microbiological flora (total viable count microorganisms, S. aureus ) of raw milk [12]. A recent study showed that high pressure processing can be an effective method of eliminating bacteria which produce spores, like Bacillus cereus [13]. Foods pasteurized by means of the HPP method are freer of microbes than products of thermal processing.…”

Bile Salt-Stimulated Lipase Activity in Donor Breast Milk Influenced by Pasteurization Techniques

“…The HPP conditions used in our study (550 MPa, 5 min) best preserved BSSL activity compared with IR, UV-C, and LTLT. Moreover, HPP has been previously shown to improve the retention of other bioactive milk proteins such as lactoferrin, lysozyme and immunological components compared with LTLT (6,9,14). Additionally, HPP minimized changes in the free fatty acid content and oxidative stability of human milk compared to Holder pasteurization (7).…”

“…Non-profit milk banks pasteurize [heating at 62.5 • C for 30 min, also known as low-temperature long-time pasteurization (LTLT)] donor milk to inactivate bacteria and viruses. However, BSSL is completely degraded by Holder pasteurization (5)(6)(7). The degradation of BSSL by pasteurization further reduces overall fat absorption from human milk 17-30%, decreasing weight gain and linear growth of preterm infants over time (1,5,8).…”

“…High-pressure processing (HPP), or high-hydrostatic pressure processing, applies pressure without heat, which inactivates bacteria and viruses in food by inhibiting their enzyme activity, damaging cell membranes, and inhibiting genetic transcription and translation (9). HPP treatment of human milk was able to maintain the bioactivity of BSSL, lysozyme and lactoferrin and minimize changes in the lipid profile compared with Holder pasteurization (6,7). Gamma-cell irradiation (IR) can inactivate bacterial and viral pathogens by damaging their DNA (among other mechanisms) (10).…”