Neutrons and Food 8 at MLZ

Acid- and rennet-induced gelation are key processing steps for dairy products such as cheese and yoghurt. Milk gelation is often affected by heat treatment, which is critical for ensuring microbial safety. Understanding how heat treatment modifies gelation behavior, is essential for optimizing dairy product processing. However, the structural changes induced by heat treatment during gelation was not completely understood, and milk from different animal origins may respond differently to heat treatment. Therefore, the aim of this study is to investigate the impact of heat treatment on acid- and rennet-induced gel in goat and cow milk. SESANS was used to probe heat-induced structural changes. A fractal model was used to identify differences in structural parameters, including fractal dimension and correlation length. These parameters correlate with the packing compactness and average aggregate size of casein micelles in gels. Heat treatment exhibited opposite effects on the fractal dimension of acid and rennet gels, with an increase observed in acid gels and a decrease in rennet gels. Compared to cow casein micelles, goat casein micelles exhibited a different sensitivity to heat treatment. In particular, rennet gels from goat milk showed fewer structural changes than those from cow milk. Overall, the results demonstrate the capability of SESANS to study structure in complex dairy systems and contribute to characterization of dairy products from different animal species.