Spray and freeze drying of human milk on the retention of immunoglobulins (IgA, IgG, IgM)

ABSTRACT

Several freeze-drying and spray-drying methods were investigated in relation to the retention of immunoglobulins (Ig) A, IgG, and IgM. Spray drying produced human milk powders with 2% humidity and a good retention of IgG (>88%) and IgM (∼70%). However, only 38% of IgA remained after spray drying. For freeze drying, only the highest heating plate temperature used in this study (40°C) brought IgA content down to 55% in powder with 1.75% residual humidity, whereas milk samples undergoing lower temperatures had higher preservation rates (75% for IgA and 80% for IgG and IgM) and higher residual moisture contents. From these results, it can be concluded that IgA is the most sensitive Ig lost during drying processing of human milk. The best method to generate human milk powders without a significant loss of Ig was thus freeze drying at 30°C heating plate temperature, which accelerated the process compared to lower processing temperatures, but still had good overall Ig retention.

KEYWORDS:

• Freeze drying
• human milk
• immunological properties
• spray drying

Acknowledgments

We would like to acknowledge the fruitful discussions and moral support to this project from nutritionists Marie-Ève Paradis (INAF, Université Laval) and Julie Lauzière and Huguette Turgeon-O’Brien (School of Nutrition, Université Laval).