Microscopic characterization of fatty liver-based emulsions: Bridging microstructure and texture in foie gras and pâté

Abstract

An analysis of food materials often involves characterization of the molecular composition of the food matrix and measuring its mechanical properties. However, there is a gap in understanding how food materials organize at the microscopic level. This article shows the application of minimally invasive coherent anti-Stokes Raman scattering (CARS) microscopy to visualize the fat distribution in duck liver-based products. Further, in combination with quantitative image analysis, CARS provides a viable route for understanding how food texture is related to food microstructure. Strong correlations were found between microscopic structural descriptors of the fat particle (abundance, shape, and size) and rheological and textural parameters (hardness, storage modulus). Foie gras was found to have an irregular shaped fat network connected via relatively weak links that yield under stress correlating with foie gras being harder, more elastic, and more brittle in comparison with a homemade duck liver pâté. In turn, the higher total number of fat particles, more round and smooth in shape, found in the pâté was responsible for it being softer and less prone to fracture. Understanding the relation between molecular composition, microscopic structure, and macroscopic texture provides opportunities for future modification of pâté formulation and/or a new preparation technique using microstructure as a texture indicator.