Freeze-drying donor human milk allows compositional stability for 12 months at ambient temperatures

Breastfeeding, which is recognised as the optimum nutrition for infants, offers numerous benefits. However, circumstances can arise when infants are unable to be breastfed from birth. In such cases, the World Health Organisation (WHO) recommends donor human milk (DHM) as the safest alternative. Current practices freeze DHM and transport it under a cold supply chain, which can create logistical challenges. Here, we investigated the efficacy of freeze-drying as a method for determining the compositional stability of DHM. The samples were freeze-dried and stored at −20°C, 4°C and ambient temperature, with sampling at 1, 3, 6, 9, and 12 months. The macronutrient composition was assessed before and after freeze-drying, protein and lipid profiles were studied using MALDI-TOF MS, and the metabolite profile was analysed through LA-REIMS. The findings revealed that freeze-drying did not significantly alter the macronutrient composition and that microbiological safety was preserved. Lipid, protein, and metabolite fingerprints remained consistent across storage conditions over 12 months. This work provides a broad insight into the compositional stability of DHM after freeze-drying. It suggests the applicability of freeze-drying for long-term preservation without a cold supply chain. The use of freeze-dried DHM may broaden its use in emergency situations and resource-limited settings.