During lipolysis of triglyceride by lipase, monoglyceride and fatty acids are produced which combine with gastrointestinal fluids to form self-assembled structures. These solubilize hydrophobic food components to promote their absorption. The aim of this study was a detailed understanding of structure formation from triglyceride digestion products with saturated short-, medium- and long chain fatty acids. Complementary characterization methods have been applied comprising small angle X-ray and neutron scattering - the latter involving the contrast matching technique using fully deuterated fatty acids polarized and depolarized dynamic light scattering and cryogenic-transmission electron microscopy. Shape, size and solubilization capacity of the self-assembled structures was dependent on composition and lipid chain length. Crystallization of fatty acid was observed when the solubility limit in the mixed bile salt micelles was exceeded; however, increasing pH and temperature increased the fatty acid solubility. The results provide insight into structure formation and crystallization of incorporated lipolysis products; this is important for a detailed understanding of food structure and nutrition, as well as the rational design of lipid based drug delivery systems. (C) 2014 Elsevier Inc. All rights reserved.