Comparison of High-Pressure and Normal-Pressure Stewing on Physicochemical and Structural Properties of Pork Bone Soup and Micro-Nanoparticles (MNPs) Inside.

Abstract

Pork bone soup, as one of the most popular worldwide diets, is famous for its desirable taste and nutritional benefits. The physicochemical properties and structural characteristics determine the quality of soup. Herein, this study investigated the impact of normal-pressure (100 kPa) and high-pressure (170 kPa) stewing on the physicochemical and structural properties of pork bone soup and its micro-nanoparticles (MNPs) inside. Normal-pressure stewing enhanced the release of proteins and triglycerides, resulting in a stable, uniform emulsion with MNPs displaying particle sizes around 260 nm, a narrow polydispersity index (PDI) (∼0.25), and good dispersion. In contrast, high-pressure stewing accelerated protein solubilization and induced extensive protein unfolding and aggregation, as evidenced by increased fluorescence intensity, elevated surface hydrophobicity, and significant shifts in Fourier transform infrared (FT-IR) and circular dichroism (CD) spectra. Although high-pressure stewing improved nutrient extraction, with protein concentrations reaching 3.46 versus 1.9 mg/mL under normal-pressure stewing, it produced less stable MNPs. Importantly, over 60% of total proteins and triglycerides were retained in MNPs under both conditions, highlighting their key role in soup stability and nutritional quality. These findings offer comparative insights into MNP behavior under different household stewing pressures and provide guidance for enhancing the quality of bone-based soups.