Mother's own milk (MOM) is the first choice for the nutritional and biological requirements of all neonates, including tiny preterm and critically ill infants. When MOM is not available or is insufficient, donor human milk from a well-recognized human milk ban¹ (HMB) is the best alternative. Although some bioactive milk components are lost to varying degrees with the heat treatment methods widely used in HMBs, many other important bioactive compounds are completely or partially preserved, which are not found in preterm formula. The greatest advantage of donor human milk for preterm infants is protection against necrotizing enterocolitis when compared to formula. This is the reason why HMBs are becoming increasingly common around the world. 

To ensure safe operation of a HMB, a well-designed safety assurance plan should be put in place. Infectious and toxicological risks are the primary potential concerns that operators of HMBs must eliminate, and these concerns are of the same types as those related to both transfusions of blood products and food consumption. HMBs implement procedures that allow for the management and sanitization of donor milk without significantly altering the nutritional and biologically protective components of human milk, obtaining a product characterized by a balance between safety and biological quality.

The infectious risk is the most relevant for recipients born preterm; however, banked human milk has very low probabilities of causing an infection and even lower probabilities of causing significant harm.

The selection of donors is the first link in a chain of procedures implemented by banks, based on the principles of Hazard Analysis and Critical Control Points (HACCP), to obtain quality milk and reduce the infectious and toxicological risk for recipients. The donor selection and exclusion processes aim to identify specific conditions that contraindicate donation, either temporarily or permanently. Donor selection must be performed by medical personnel and must only allow enrollment of low-risk donors. Enrollment is based on the existing rules for blood donation, which have been adapted to the different degree of risk of human milk. 

To become donors, lactating women must be in good health, lead a healthy lifestyle, be negative in biological qualification tests, and produce milk in excess of their children's needs. The reliability of the donors is important, as are their training and the establishment of a relationship of trust. For example, donors must be informed of the correct ways to implement extraction and store milk at home. 

Before each collection, it is critical for donors to wash their hands thoroughly. The breasts, particularly the areolar zone and the nipple, should be cleaned, as well. To avoid harming the skin with frequent use of detergents, it is sufficient to wash only with running water or with gauze soaked in water. In the donors' homes, inadequate monitoring of refrigerator temperatures can cause microbiological multiplication with increased contamination. Most of the problems involving the quality of human milk result from inappropriate home collection and handling, with frequent contamination from the environment. For this reason, it is advisable to freeze the milk within 24 hours after its expression. 

Transporting the milk from home to the milk bank should be carried out in such a way that the milk arrives at the bank in a frozen state. The milk received by the HMBs must be stored, while maintaining the cold chain, with continuous temperature monitoring and subjected to checks that measure the quantity of bacteria present in it. If the milk is contaminated beyond a certain limit, then it must be discarded. However, it is also essential to periodically verify the reliability of the donors, the procedures, and the suitability of the environment and the equipment, according to HACCP principles. This can be done by means of routine bacteriological and quality checks on the milk, the environment, the equipment, and on the operators involved.

When donor milk is expressed and collected directly at the bank, it should be transferred immediately to the refrigerator and pasteurized as soon as possible, preferably within 24 to 72 hours. If a waiting time longer than 72 hours is foreseen for pasteurization, then the milk should be frozen as soon as possible.

Pasteurization is an effective means for sanitizing milk. All milk that arrives at a HMB must be pasteurized. Holder pasteurization is recommended, and it is performed using a lower temperature and longer time (62.5 °C/144.5 °F for 30 minutes). If performed correctly, pasteurization inactivates pathogenic bacteria, reduces the total microbial load, and inactivates several enzymes, thereby stabilizing the milk and making it more appropriate for storage. Compared to sterilization, which eliminates all microorganisms and spores but drastically alters the biological characteristics of the food, pasteurization preserves the bioactive and nutritional components of the milk while effecting a moderate and acceptable reduction of pathogens. 

After pasteurization, human milk should be stored in a freezer at a temperature of less than or equal to –20 °C/–4 °F and should be used within a maximum of six months from the date of expression. Donor human milk should be used within a maximum of three months when utilized for feeding preterm neonates. Pasteurization is essential for the safety and quality of donated milk, but it represents only a part of the chain of the entire process managed by HMBs. The precise meticulousness of the system is guaranteed only if there are no weak links; hence, the importance of managi­ng the milk by observing correct procedures throughout the supply chain. 

HMB operators must compulsorily implement self-monitoring, at whatever level they are involved in the food chain, to guarantee control of the hygiene and safety of the final product. HMBs must also document the methods of implementation of the procedures carried out, retaining the documentation for correct and secure human milk management. Only by following these precautions can HMBs produce and offer safe donor human milk of high nutritional quality.

Reference

1. Arslanoglu, S., G. E. Moro, P. Tonetto, et al. "Recommendations for the establishment and operation of a donor human milk bank." Nutrition Reviews 81, no. 1 (March 2023): 1–28. https://doi.org/10.1093/nutrit/nuad012.