[Impact of pasteurization/freeze-drying on available immunoglobulin content of the mature human milk. Use in human milk banking of hospitals].

INTRODUCTION

This study analyzes the effect on the content of immunoglobulins and C3 complement of freeze drying after pasteurization by three different methods in mature human milk (MHM).

OBJECTIVE

Freeze drying is proposed as a complementary method for the maintenance of MHM therapeutic properties with greater validity.

METHODS

This was a descriptive study in which MHM samples were obtained. Next, aliquots of the samples obtained were pasteurized by three methods: 62.5 centigrades degrees/30 minutes, 72 centigrades degrees/15 minutes, 85 centigrades degrees/5 minutes, followed by a rapid cooling at 5 ºC. Then, 30 ml volumes of pasteurized sample were freeze-dried over a period of 36 hours. Total protein determination was performed by the Lowry method. The concentrations of immunoglobulins A, G and M, and complement C3, were determined by conventional nephelometric technique following the manufacturer's instructions. Statistical significance was defined as p < 0.05.

RESULTS

The method of pasteurization of MHM with increased protein and immunoglobulin retention was at 62.5 centigrades degrees, however, pasteurization at 72 centigrades degrees before freeze-drying showed better retention of immunoglobulins.

CONCLUSIONS

Our results suggest that the freeze-drying of pasteurized MHM is a suitable method for the conservation in human milk banks. Both the nutritional composition and the extension of its validity and the application of the two processes together provide the advantage of maintaining the therapeutic properties of human milk to improve the health of the newborn in a vulnerable, impaired or immunosuppressed state.