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New peer-reviewed study finds vat pasteurization retains molecular structure of naturally occurring bioactive proteins in human donor milk, similar to raw breast milk

Vat pasteurization preserved more of the bioactive proteins than ultra-high-temperature or retort sterilization, especially immunoglobulins, lactoferrin, and caseins

DUARTE, Calif., Oct., 4, 2022 – Prolacta Bioscience®, the world’s leading hospital provider of 100% human milk-based nutritional products for critically ill, premature infants, announced today the publication of a journal article that compares the effects of various manufacturing methods on bioactive proteins in donor human milk.

The naturally occurring bioactive proteins in human milk play a vital role in infant nutrition. In addition to providing key nutrients like amino acids, calcium, and phosphorus,1 bioactive proteins also protect against bacterial and viral infections and contain anti-inflammatory properties.2

The peer-reviewed article, which focuses on structural and functional changes of bioactive proteins, found that the molecular structure of bioactive proteins in donor human milk that had been vat pasteurized most closely resembled those in raw milk controls, compared with other human milk processing methods, including ultra-high-temperature (UHT) sterilization and retort sterilization.2

Authored by Ningjian Liang, PhD; David C. Dallas, PhD; and colleagues at Oregon State University and the University of California, Davis, “Structural and Functional Changes of Bioactive Proteins in Donor Human Milk Treated by Vat-Pasteurization, Retort Sterilization, Ultra-High-Temperature Sterilization, Freeze-Thawing and Homogenization” was published in September in the peer-reviewed journal Frontiers in Nutrition.2 The study compared the effects on human milk when treated by commonly used processing methods.

The researchers concluded that different bioactive proteins have different sensitivity to the treatments tested. Overall, vat pasteurization preserved more of the bioactive proteins than UHT sterilization or retort sterilization did. This was especially true of three bioactive proteins: immunoglobulins, lactoferrin, and caseins.2

Intake of human milk is especially critical for babies born prematurely, with mother’s own milk (MOM) being the best feeding option. When an adequate amount of MOM is not available, the American Academy of Pediatrics recommends the use of donor human milk.3

Donor human milk must be processed to eliminate the possibility of pathogen contamination before being given to infants in the neonatal intensive care unit (NICU).4,5 Once the milk is processed and/or pasteurized to ensure safety, bioactivity is impacted.6,7 But prior to this study, the extent of those changes based on each processing method were unknown.

“Currently, donor milk processors lack information about the extent to which different processing techniques degrade or preserve bioactive milk proteins. Our study addresses this critical research gap as we examined the extent to which various treatments can preserve bioactive proteins,” wrote Liang, a postdoctoral researcher in the laboratory of David Dallas, an assistant professor in the College of Public Health and Human Sciences at Oregon State University. “This information will support milk processors in determining how to optimally process donor milk to preserve specific milk proteins.”

Liang et al. tested processed milk samples using the SDS-PAGE method, which separates proteins based on their molecular weight. They then tested the milk samples using the enzyme-linked immunoabsorbent assay (ELISA), a widely used laboratory technique that measures proteins and other substances.

“The more we learn about the importance of bioactivity in human milk, the more important it is that we understand how processing affects the milk we rely on to provide optimal nutrition to our patients,” said Melinda Elliott, chief medical officer of Prolacta and a practicing neonatologist. “This study reinforces that how human milk is processed matters. Prolacta’s human milk-based products are vat pasteurized to preserve as much of the natural bioactivity of the milk as possible.”

Human donor milk providers use several methods to process human milk, including:

  • Vat and Holder pasteurization: Heating milk to a set temperature to inactivate contaminants including bacteria and viruses. The process may reduce the activity and concentration of milk enzymes and some bioactive proteins.6
  • Retort sterilization: Commercial canning method that exposes milk to high temperature and pressure. This method inactivates bacteria and viruses and is shown to result in greater damage to bioactive proteins when compared to vat and Holder pasteurization.2,6
  • Ultra-high temperature (UHT) processing, with or without homogenization: Heating milk to high temperatures and homogenization, a process that evenly disperses two liquids to create a single uniform mixture, cause structural and compositional changes to the milk fat globule membrane (MFGM). Separately or in combination, these processes may play an important role in the decrease of MFGM bioactivity.8,9

About Human Milk-Based Nutritional Products

The major difference between cow milk-based and human milk-based nutritional products is the composition — notably, the bioactive components that are unique to human milk. These include immunoglobulins, lactoferrin, milk fat globule membrane, and the wide spectrum of prebiotics known as human milk oligosaccharides (HMOs), which are not easily manufactured and thus are greatly decreased or missing from cow milk-based nutritional products.10 Bioactivity is thought to support infants’ immunity, development, growth, and long-term health.11

Prolacta’s 100% human milk-based nutritional products have the highest bioactivity in the human milk industry.12 Prolacta’s nutritional products are vat pasteurized using temperature profiles defined by the U.S. Food and Drug Administration (FDA) to ensure pathogen inactivation and the highest level of safety while retaining as much of the natural bioactivity of the milk as possible.12 Prolacta’s vat pasteurized products retain higher bioactivity than products processed using other methods, including retort sterilization and UHT processing.2,6,7

About Prolacta Bioscience

Prolacta Bioscience® Inc. is a privately held, global life sciences company dedicated to Advancing the Science of Human Milk® to improve the health of critically ill, premature infants. Prolacta’s 100% human milk-based nutritional products have been evaluated in more than 20 clinical studies published in peer-reviewed journals. More than 80,000 premature infants have benefited from Prolacta’s nutritional products worldwide to date.13 Established in 1999, Prolacta is the world’s leading provider of human milk-based nutritional products for hospital use and is also exploring the therapeutic potential of human milk across a wide spectrum of diseases. Prolacta maintains the industry’s strictest quality and safety standards for screening, testing, and processing donor human milk. Operating the world’s first pharmaceutical-grade human milk processing facilities, Prolacta uses vat pasteurization and a patented, FDA-reviewed manufacturing process to ensure pathogen inactivation while protecting the nutritional composition and bioactivity of its human milk-based products. Prolacta is a global company with headquarters in Duarte, California, and can be found online at Twitter, Instagram, Facebook, and LinkedIn.

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Media Contact:
Loren Kosmont


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  11. Gila-Diaz A, Arribas SM, Algara A, Martín-Cabrejas MA, López de Pablo ÁL, Sáenz de Pipaón M, Ramiro-Cortijo D. A review of bioactive factors in human breastmilk: a focus on prematurity. Nutrients. 2019;11(6):1307. doi:10.3390/nu11061307
  12. Data on file.
  13. Estimated number of premature infants fed Prolacta’s products from January 2007 to May 2021; data on file.