Relating structural properties to saltiness perception of model lipoproteic gels

Sodium reduction in processed foods is an urgent mission to tackle sodium overconsumption. Eighty-nine percent of US adults consume more than the recommended amount of sodium, leading to the high prevalence of hypertension. Lipoproteic foods including cheese and processed meats are potential targets for sodium reduction, as they form the major source of sodium in modern diets. Structural engineering to enhance sodium release and saltiness perception is promising for sodium reduction in lipoproteic foods, which release as low as only 5% of sodium during mastication. The goal of this research is to relate structural properties, including porosity and particle size of fat, to the saltiness perception of a mode lipoproteic gel system. The outcome of this research can imply strategies for structural engineering to enhance the saltiness perception of lipoproteic foods. Solid lipoproteic colloid (SLC), a solid matrix made of lipid and protein in the oil-in-water emulsion structure, was used as the model food in this study. The SLCs were made with varying contents of protein, fat, and NaCl. Two levels of homogenization pressure were applied to the emulsion before the heat-induced gelation to form the SLCs. The images of the SLC microstructure was captured using environmental scanning electron microscopy (ESEM), and the porosity was quantified using an image analysis of the ESEM observations. The gyration radius of fat (Rg,f) in the SLCs was quantified using ultra-small-angle X-ray scattering with a synchrotron-source. Serum release, which is the amount of liquid compressed out from the SLCs, and textural properties were measured using a texture analyzer. A conductivity meter was used to measure the in vitro sodium release during the compression of the SLCs in water by a texture analyzer. Sensory evaluations were carried out on the SLCs with 1.5% NaCl. A quantitative descriptive analysis (QDA) method was used to characterize the saltines and textural properties of the SLCs. A time-intensity (TI) method was used to evaluate the temporal saltiness perception properties of the SLCs. The saltiness of the SLCs correlated positively with the porosity, but did not correlate with the Rg,f. The increased saltiness with increasing porosity was due to the greater serum release which enabled rapid sodium release. The lack of the effect of Rg,f on the SLC saltiness was due to the counteracting impacts of the Rg,f on the sodium release. Lowering the Rg,f led to more extensive breakdown but less serum release of the SLCs. The increased sodium release with increased sample breakdown was counteracted by the decreased sodium release due to decreased serum release. This study revealed the structural influences focused with porosity and particle size of fat on the saltiness perception of lipoproteic model foods. The results implied the potential to enhance the saltiness of lipoproteic products with optimized porosity and particle size of fat. Future studies can aim at modulating the structure toward higher saltiness while maintaining the sensory acceptance of the lipoproteic products. Also, future evaluation of the in-mouth sodium release can provide more fundamental information in the saltiness perception of SLC foods