From dairy to plant products: Understanding their structural fingerprints with X-rays.

Global interest in milk alternatives increases rapidly due to health awareness, their allergen-friendliness, and concerns about sustainability. While dairy product microstructure and rheology are widely studied, plant-based alternatives remain less understood, with limited comparative studies of different plant sources and brands. This study uses ultra-small, small and wide-angle X-ray scattering (USAXS, SAXS, WAXS) to analyse structural fingerprints of commercial plant-based milk, yoghurt and cream alternatives versus dairy products. These techniques allow characterization across multiple length scales from large oil droplets and aggregated structures to carbohydrate/protein networks and glyceride crystalline phases. Correlations between intensity and fat (USAXS) and carbohydrate content (SAXS) provide structural insights, while SAXS and WAXS data correlated with solid fat and crystal packing are important for melting behaviour and viscosity perception. Light scattering confirmed fat-content-related size trends and revealed larger structures of non-lipid materials in plant-based samples. The study provides a basis for understanding scattering data where structural fingerprint plots, using colour scales to compare intensity and intensity gradient, allow ready data interpretation that will be beneficial for analysis with artificial intelligence (AI) tools. This approach helps optimize plant-based formulations by connecting structure and functionality and demonstrates the potential of scattering techniques in food structure research and design.