Researchers develop innovative method for preservation of human milk | Gdańsk University of Technology

Breast milk is perfectly suited to the needs of infants. When taken early in life, it has a huge impact not only on the physical condition and development, but also on mental and neurological development. Breast milk is particularly important for newborns who must be hospitalized, yet not all small patients can be fed by their mothers. Milk Banks were established for optimal nutrition of patients in neonatal care units. These are professional laboratories that collect milk from voluntary donors, test it, store it safely and deliver it to infants in hospitals. Currently, there are 16 milk banks operating in Poland , which also support health care units in the region that do not have such laboratories.

Prof. Edyta Malinowska-Pańczyk from the Faculty of Chemistry cooperates with the Milk Bank at the University Clinical Center in Gdańsk. She conducts research on optimizing safe storage of breast milk. The research is conducted as part of the project “Storage of human milk in unfrozen state under high pressure-subzero temperature conditions - new method of preservation”, funded from Small Grant Scheme 2020 by the National Centre for Research and Development.

Multiple freezing and pasteurization

Milk obtained from donors goes a long way before it reaches the newborn. First, it is frozen and stored for up to 3 months at a temperature of -20°C. The milk is then thawed, portioned, pasteurized and re-frozen. It can be stored in this condition for up to 6 months (from the moment of expressing the milk).

– Unfortunately, this process strongly affects the quality of milk. – explains Prof. Edyta Malinowska-Pańczyk, project manager. – Pasteurization involves heating it for 30 minutes at a temperature of 62.5°C and this manipulation causes the loss of many bioactive ingredients. They are unique and cannot be reproduced in any artificial formula. Moreover, there is also a risk of secondary contamination with spore-forming bacteria that survive the pasteurization process.

High pressure instead of high temperature

The researcher’s idea is to replace the multi-stage freezing and thawing of milk and pasteurization with storage under increased pressure at temperatures below 0°C. In this method, water does not crystallize and milk can be stored unfrozen for a long time.

– High pressure also has a bactericidal effect, yet allows the preservation of bioactive ingredients. Therefore, this process is less harmful to milk than pasteurization - emphasizes the researcher. - As part of our project, a prototype of a device for generating pressure at a temperature below 0°C and storing it in these conditions was designed and built for samples with a volume of up to 100-150 ml. We are also constantly conducting research on changes in the content of selected nutrients and biologically active ingredients and the degree of inactivation of microbiota in milk during storage in high-pressure and low-temperature conditions.

The research team also includes Prof. Dorota Martysiak-Żurowska, who has been examining breast milk for many years, Prof. Barbara Kusznierewicz and Katarzyna Mazur, M.A.

The final research results will be published early 2024, but the researchers already admit they are optimistic and  think that replacing pasteurization with high pressure and low temperature may be used as a milk storage method in Milk Banks in the future.

 – This method allows to eliminate bacteria in milk fed to infants, while maintaining its composition similar to that offered by the mother. Additionally, this method is less energy-consuming than the milk storage procedure currently used in milk banks - emphasizes Prof. Malinowska-Pańczyk.

The project ends in January, but the research will continue.

– We need to complete the results which will allow us to determine whether virus particles are also eliminated under these conditions. We are currently investigating the milk for survival of pathogenic bacteria. However, it must also be free of active virus particles, especially cytomegalovirus, which is dangerous for prematurely born babies. Moreover, we will check changes in the milk metabolone that occur during storage, explains the researcher.