Modeling the breakdown of starch gels during simulated mastication: role of salivary amylase, botanical origin, and retrogradation

During oral processing, food structure changes are influenced by the mechanical forces of chewing and the enzymatic activity of salivary α-amylase (SA). This study explores the influence of SA on the textural and rheological properties of starch gels derived from corn, potato, and pea, stored for 0, 24, and 48 hours. Gels were subjected to repeated compression cycles and rheological testing, with and without saliva. Two models, first-order kinetics and Peleg’s model, were applied to describe the mechanical behavior under simulated mastication, and SEM analysis provided insights into the microstructure. Pea starch gels exhibited the highest hardness and G′, while potato gels were most susceptible to enzymatic hydrolysis. Storage promoted retrogradation, particularly in pea and potato starches, increasing rigidity. The fragile structure of potato gels against continuous mechanical compression facilitated the enzymatic action, notably reducing their gel integrity. Strong correlations were found between amylose content and resistant starch (r= 0.76; p <0.05), hardness parameters H inf (r=0.78, p <0.05) and Ho (r=0.86, p <0.05), as well as negative correlations with Peleg constants k 1 (r=-0.76, p <0.05) and k 2 (r=-0.77, p <0.05). Resistant starch also positively correlated with H inf (r = 0.80, p < 0.05) and Ho (r = 0.84, p < 0.05) and negatively correlated with k 2 (r = -0.79, p < 0.05), indicating that high amylose content promotes resistant starch formation and a hard, brittle gel network. Peleg’s model provided a better fit for textural changes during repeated compression and the saliva effect (R 2 = 82.76–94.43%) compared with the Box–Lucas model (R 2 = 35.18–91.10%). These findings reveal how enzymatic activity during oral processing affects the structure and function of starch gels.