Swelling than diffusion behavior of starch under protein crowding conditions affects the texture of the protein/starch blend gels

The study evaluated the swelling and diffusion behaviors of crosslinked/acetylated tapioca starches with various modification degrees under myofibrillar protein (MP) crowding. It also evaluated their relationship with the MP/starch blend gel performance. The swelling ratio (SR) of starch granules decreased significantly from 2.26 to 3.00 in the absence of MP to 1.74–1.96 under MP crowding, with the minimum SR (1.74) for high-crosslinked/high-acetylated TS (HC-HA-TS), which indicated MP crowding and highly crosslinked/acetylated modification reduced starch granule swelling significantly. Furthermore, there was minimal protein diffusion into the starch matrix, but significant amylose diffusion into the MP matrix, forming a starch-protein coexisting region. HC-HA-TS had the smallest average diffusion area, while raw TS had the largest. SR and diffusion area variations are due to the modification methods and degrees used, where crosslinking inhibits swelling while acetylation promotes it, as well as the constraints imposed by MP gelation. In our correlation analysis, we found that starch diffusion had little effect on the texture of MP/TS gels regardless of MP presence or absence; instead, starch swelling was the dominant factor, with a higher SR under MP crowding contributing to the enhanced texture. [Display omitted] •Crosslinking restricts starch swelling and diffusion, while acetylation promotes it.•Swelling and diffusion of starch in protein matrix were detected by S-FTIR imaging.•Protein and starch interdiffusion formed certain compatible structures.•Starch swelled less under protein crowding than without protein crowding.•Swelling than diffusion of starch under protein crowding affected texture of blend.