The Cryopolitics of Human Milk: Thermal Assemblages of Breast Milk in Donation, Banking, and Bioindustrial Research

Cold is indispensable when preserving breast milk for later use in ordinary breastfeeding practices and, in addition to other devices such as the breast pump, fridges and freezers have been essential in making human milk a mobile biosubstance. Cryotechnologies become even more important when donated milk has to be preserved for the feeding of hospitalized babies or when, in the form of milk probiotics, it enters the realms of scientific research and industrial production. However, attention to cold only offers one side of the picture, as thawing and heating are essential processes in human milk circulation too. Drawing on research on milk banking practices in Spain, we present three instances where technologies of cold and heat are applied to human milk or its components: hospital banks that collect milk from donors; the practices of lactating women who donate part of their milk to hospital banks, share it informally with other women, or participate in clinical research; and biopharmaceutical companies developing cutting-edge nutritional products employing microbial strains obtained from breast milk. Each of these scenarios resorts to different technological manipulations of cold and heat, generating distinct thermal assemblages where technical questions and sociocultural logics are simultaneously at stake.