Influence of refrigeration or freezing on human milk macronutrients and energy content in early lactation: Results from a tertiary centre survey

Abstract

Background: Neonates with severe conditions that cannot be breastfed should receive fresh or preserved expressed human milk in addition to parenteral nutrition. Objective: To identify the time during lactation when the macronutrients provide maximum energy and evaluate the effect of refrigeration and freezing. Methods: We analyzed the composition of fresh milk, refrigerated at +4°C and frozen at −20°C, expressed by mothers of 60 preterm and 30 term infants from a level III maternity, in colostrum, transitional, and mature milk. Results: In fresh milk, the protein level constantly decreases during lactation, with a significant difference after 3 weeks of lactation. Preterm milk of day 21 and day 30 had significantly lower protein than term milk (1.27 versus 1.43 g/dL, P=0.015 and 1.13 versus 1.28 g/dL, P=0.001). Refrigeration for 72 hours of term milk decreased protein content less than freezing. Preterm colostrum has significantly less protein after 48 hours of refrigeration or freezing. Preterm milk from day 60 lost carbohydrates if refrigerated 72 hours or frozen for 2 months. Lipids in preterm colostrum decrease after 8 weeks of freezing. Refrigeration for up to 72 hours did not change significantly the energy value of colostrum or transitional milk. Freezing preterm milk more than 2 weeks leads to significant loss of energy. Conclusions: Milk frozen for more than 2 weeks contains less protein and energy than milk refrigerated for up to 72 hours. In the absence of milk bank access, in common settings, short-term refrigeration is preferable to long-term freezing.

Effects of freezing as a post-harvest storage technique on quality of Friesian crossbred cattle milk

“…The decrease in milk constituents was attributed to coagulation and degradation when frozen milk is thawed. Specifically, the protein decrease was in agreement with a previous study by Păduraru et al (2019) on the influence of refrigeration or freezing on human milk macronutrients. Another study by Vieira et al (2011) reported up to 13.6% decrease in protein content when human milk was frozen and thawed.…”

Freezing Effect as a Post-Harvest Storage Technique: Quality of Buffalo Milk

“…Buffalo milk is ideal for making butter, cream, and yoghurt because of its high protein and fat content, which gives it a rich and delicate texture. In particular, the trend towards lower protein concentration is consistent with a prior study on the effects of freezing or refrigeration on the macronutrients in human milk reported by Pȃduraru et al [33]. The decrease in protein has been attributed to several factors.…”

The Effect of Prolonged Freezing and Holder Pasteurization on the Macronutrient and Bioactive Protein Compositions of Human Milk

“…A summary of 44 articles 15 demonstrated that Holder pasteurization has the highest effect on the composition of bioactive components in human milk. Inconsistent findings from previous studies could be explained by the duration and temperature at which milk samples are stored before pasteurization, 16,17 method of thawing, 18 by the quantities of milk being pasteurized, by the choice of equipment for Holder pasteurization, 15,19 and finally by the method used to prepare the milk samples for testing. 20 Our study has demonstrated that the storage of frozen human milk at -40°C up to 10 months, followed by thawing and pasteurization, has no significant effect on macronutrient (protein, fat, and carbohydrate) or energy content of human milk.…”