The bioactive compounds and all the necessary nutrients required by newborn babies are provided by breast milk. All these nutrients are important for development, growth, and protection by enforcing immunity. However, sometimes a mother is not able to produce enough milk to fulfill the baby’s requirements. In such a case, human milk banks provide breast milk for newborns .
Human milk banks usually pasteurize the donated breast milk. During pasteurization, milk is heated at a low temperature i.e., 65°C for a long duration. This guarantees safety against microorganisms but at the same time, many important bioactive nutrients degrade . A method that minimizes the loss of important nutrients from breast milk over longer durations is needed and one such method is freeze-drying.
WHAT IS THE TECHNIQUE OF FREEZE-DRYING?
Freeze-drying or lyophilization entails freezing along with the sublimation process and extraction of moisture. This results in minimal changes in the components of the product being frozen. This process decreases the water activity and the outcome is reduced bacterial growth. It also decelerates the unfavorable enzymatic processes [3–5].
BENEFITS OF FREEZE-DRYING BREAST MILK
With the process of freeze-drying, all the important nutrients are locked and the shelf life of the milk is increased in comparison to frozen liquid milk. Since milk is dehydrated, you do not have to worry about storing it in the fridge and a lack of moisture prevents bacterial growth and delays the oxidation of fat .
For antioxidants that are sensitive to heat such as ascorbic acid and tocopherols, the freeze-drying technique is particularly suitable for them. This technique also removes the limitations associated with traditional freezing by decreasing the space required for storage, and ease of transport while preserving the nutritional characteristics and flavor of milk [7,8].
IMPACT OF FREEZE DRYING ON THE MILK NUTRIENTS
A significant portion of a baby’s diet should consist of fats because it supports the healthy development of the brain, helps in the absorption of vitamin A, D, E, and K, that are fat-soluble and also provide protection to the nervous system. A 2014 study reported that the fat composition of freeze-dried breast milk remains unaltered along with antioxidant tocopherol .
Another study found that after freeze-drying breast milk, no substantial difference was observed in the enzymatic activity and the amount of proteins. Freeze-drying protects the functionality of protein in breast milk which is often lost when using heat treatments of preservation .
Glycoproteins present in human breast milk play an important role in the fight against disease-causing microorganisms . Lactoferrins are popular glycoproteins that decrease when human breast milk is frozen for three months or more . A 2020 study found that freeze-drying breast milk has no significant effect on the levels of lactoferrin .
THE BOTTOM LINE
Freeze-drying breast milk by human milk banks using commercial freeze dryers or even at home using small freeze dryers provides an opportunity to preserve the nutritional value of the breast milk for longer durations along with making storage easier and more convenient. Basically, the freeze-drying technique creates a win-win situation.
- WHO. Global strategy for infant and young child feeding [Internet]. 2003 [cited 2022 Sep 3]. Available from: https://www.who.int/publications-detail-redirect/9241562218
- Peila C, Moro GE, Bertino E, Cavallarin L, Giribaldi M, Giuliani F, et al. The Effect of Holder Pasteurization on Nutrients and Biologically-Active Components in Donor Human Milk: A Review. Nutrients. 2016 Aug 2;8(8):E477.
- Ciurzyńska A, Lenart A. Freeze-Drying - Application in Food Processing and Biotechnology - a Review. Pol J Food Nutr Sci. 2011 Sep 30;61(3):165–71.
- Moses JA, Norton T, Alagusundaram K, Tiwari BK. Novel Drying Techniques for the Food Industry. Food Eng Rev. 2014 Sep 1;6(3):43–55.
- Duan X, Yang X, Ren G, Pang Y, Liu L, Liu Y. Technical aspects in freeze-drying of foods. Dry Technol. 2016 Aug 17;34(11):1271–85.
- Shofian NM, Hamid AA, Osman A, Saari N, Anwar F, Dek MSP, et al. Effect of freeze-drying on the antioxidant compounds and antioxidant activity of selected tropical fruits. Int J Mol Sci. 2011;12(7):4678–92.
- Ratti C. Hot air and freeze-drying of high-value foods: a review. J Food Eng. 2001 Sep 1;49(4):311–9.
- Vega-Mercado H, Marcela Góngora-Nieto M, Barbosa-Cánovas GV. Advances in dehydration of foods. J Food Eng. 2001 Sep 1;49(4):271–89.
- Lozano B, Castellote AI, Montes R, López-Sabater MC. Vitamins, fatty acids, and antioxidant capacity stability during storage of freeze-dried human milk. Int J Food Sci Nutr. 2014 Sep 1;65(6):703–7.
- Valentina C, Andrés S. The Effect of Freeze-Drying on the Nutrient, Polyphenol, and Oxidant Levels of Breast Milk. Breastfeed Med [Internet]. 2016 Dec 1 [cited 2022 Sep 3]; Available from: https://www.liebertpub.com/doi/10.1089/bfm.2016.0102
- Liu B, Newburg DS. Human Milk Glycoproteins Protect Infants Against Human Pathogens. Breastfeed Med. 2013 Aug;8(4):354–62.
- Rollo DE, Radmacher PG, Turcu RM, Myers SR, Adamkin DH. Stability of lactoferrin in stored human milk. J Perinatol. 2014 Apr;34(4):284–6.
- Hahn WH, Bae SP, Lee H, Park JM, Park S, Lee J, et al. The impact of freeze-drying on the glycoproteomic profiles of human milk. Anal Sci Technol. 2020;33(4):177–85.