Abstract
<title>Abstract</title> <p>Driven by the rising demand for healthy diets, vegetable oil-based oleogels as animal fat substitutes have attracted increasing research attention. In this study, a starch-protein composite oleogel was prepared by emulsion templating method, using protein-glutaminase (PG)-modified glutinous rice flour (GRF)/soy protein isolate (SPI) complex as the gelator. The effects of deamidation degree and flour/protein ratio on the physicochemical properties of PG-modified GRF/SPI emulsions (PG-GRPE) and corresponding oleogels (PG-GRPO) were systematically investigated. Results demonstrated that emulsifying properties, particle size and absolute ζ-potential first increased and then decreased with the increase of SPI substitution and deamidation degree. Notably, deamidation significantly enhanced the oil-binding capacity of GRPO from 24% to 98%. The optimal formulation of PG-GRPO was determined as follows: 14% deamidation, 40% SPI mass ratio and pH 6.0, which exhibited physicochemical and mechanical properties most similar to those of commercial butter. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) analysis revealed that PG modification altered the protein secondary structure with an increased proportion of α-helix, disrupted, and facilitated the formation of a stable amylopectin-protein hydrogen bond gel network. Application in piped cookies showed that the optimized PG-GRPO could fully replace butter, yielding dough with comparable processability to that of butter-based dough. The finished cookies presented butter-like appearance and texture parameters, and effectively suppressed starch retrogradation during storage. This research clarifies the formation mechanism of PG-modified starch-protein hydrogen bond gel networks, provides theoretical and technical support for the development of plant-based oleogel as animal fat alternatives.</p>