Hot or not? Modulating the functionality of artificial casein micelles with the preparation temperature

Abstract

Identifying optimal conditions for the efficient future production of artificial casein micelles (ACM) with precision fermentation-derived caseins is essential for their application in future foods. However, casein micelles naturally form under physiological conditions with little variation, rendering it difficult to study how temperature and other factors affect their assembly. This study evaluated whether the temperature during the artificial assembly of caseins into casein micelles has a lasting impact on ACM properties and functionality. ACM were prepared at temperatures between 5 and 65 °C and stored and analysed at a fixed temperature. Micelle formation was most efficient at 37 °C, yielding the highest level of micellar casein. Casein aggregation occurred at both lower and higher temperatures, with the fraction of serum casein increasing at higher temperatures, leading to reduced micellar casein levels. Additionally, the fraction of micellar calcium phosphate and magnesium, as well as the size of calcium phosphate nanoclusters, increased with higher preparation temperatures, while micellar size and hydration decreased, resulting in denser structures. These structural and compositional changes impacted functionality, with ACM prepared at intermediate temperatures (25 and 37 °C) producing the firmest curds upon rennet coagulation, while foam stability improved for ACM prepared at lower and especially higher (65 °C) temperatures. The preparation temperature thus had irreversible effects on the ACM properties, offering a means to tailor ACM to specific applications in future foods.