RT Journal Article T1 Effect of Freezing Time on Macronutrients and Energy Content of Breastmilk A1 García-Lara, Nadia Raquel A1 Escuder Vieco, Diana A1 García Algar, Oscar A1 De la Cruz, Javier A1 Lora Pablos, David A1 Pallas Alonso, Carmen Rosa AB Background: In neonatal units and human milk banks freezing breastmilk at less than -20 °C is the choice for preserving it. Scientific evidence in relation to the loss of nutritional quality during freezing is rare. Our main aim in this study is to determine the effect of freezing time up to 3 months on the content of fat, total nitrogen, lactose, and energy. Our secondary aim is to assess whether ultrasonic homogenization of samples enables a more suitable reading of breastmilk macronutrients with a human milk analyzer (HMA) (MIRIS, Uppsala, Sweden).Methods: Refrigerated breastmilk samples were collected. Each sample was divided into six pairs of aliquots. One pair was analyzed on day 0, and the remaining pairs were frozen and analyzed, one each at 7, 15, 30, 60, and 90 days later. For each pair, one aliquot was homogenized by stirring, and the other by applying ultrasound. Samples were analyzed with the HMA.Results: By 3 months from freezing with the two homogenization methods, we observed a relevant and significant decline in the concentration of fat and energy content. The modification of total nitrogen and lactose was not constant and of lower magnitude. The absolute concentration of all macronutrients and calories was greater with ultrasonic homogenization.Conclusions: After 3 months from freezing at -20 °C, an important decrease in fat and caloric content is observed. Correct homogenization is fundamental for correct nutritional analysis. PB Mary Ann Liebert Inc SN 1556-8253 SN 1556-8342 YR 2012 FD 2012-08 LK https://hdl.handle.net/20.500.14352/116126 UL https://hdl.handle.net/20.500.14352/116126 LA eng NO García-Lara NR, Escuder-Vieco D, García-Algar O, De la Cruz J, Lora D, Pallás-Alonso C. Effect of freezing time on macronutrients and energy content of breastmilk. Breastfeed Med. 2012 Aug;7(4):295-301. doi: 10.1089/bfm.2011.0079. Epub 2011 Nov 2. PMID: 22047109; PMCID: PMC3411345 NO Instituto de Salud Carlos III (ISCIII) DS Docta Complutense RD 10 abr 2025