The impact of pH environment on the lubrication performance of starch gel in simulating oral processing

The impact of varying pH conditions on the physical properties of corn and potato starch gels in simulating oral processing was investigated. Significant alterations in pH values were observed following treatment with different concentrations of citric acid (0.005%, 0.01%, and 0.1%) and sodium bicarbonate (1%), with statistically significant differences noted (P<0.05). The visual morphology, texture characteristics, water distribution, rheological properties, and tribology were analyzed. An alkaline pH of approximately 8.1 significantly enhances the lubricity of corn and potato starch gel pellets. Partial least squares regression (PLSR) analysis under various acidic conditions revealed that water plays a crucial role in gel lubrication systems. Specifically, free water (A24) is positively correlated with lubrication properties (and negatively correlated with the friction coefficient) (P<0.05). The hardness of the starch gel demonstrated a significant negative correlation with the friction coefficient (P<0.05), while the apparent viscosity of the starch gel pellets exhibited a significant positive correlation with the friction coefficient (μ) (P<0.05). Modifying the pH level in acidic environments can substantially alter the lubricity of both corn and potato starch gel pellets (P<0.05). These findings provide valuable theoretical insights for optimizing sensory texture in the processing of starch-based foods.