Modulating elasticity of heat-set soy protein-curdlan gels by small phenolic acids

Fish-gel products with a bouncy texture are integral to the gastronomy of many regions in Asia. Despite the current alternative protein food megatrend driven by sustainability, plant-based fish-gel analogues are not popularised due to the lack of accessible technical know-how in tailoring textural nuances convincingly. Here, we studied how two readily available small phenolic acids, i.e., gallic acid and ferulic acid, had differing interactions with curdlan and soy protein. Noteworthily, we found that when ferulic acid and trehalose were coexistent in mM concentrations at pH 6, (i) permanent interaction between soy protein and ferulic acid at >= 40 degree Celsius was mild (as according to precision ellipsometry); (ii) protein aggregation in a bicontinuous microstructure with curdlan network (3% w/w) and auxiliary protein phase (16.2% w/w) was restrained (as according to epifluorescence microscopy); and (iii) comparable to real commercial fishball, the resultant heat-set gel displayed large change in gel stiffness at 60-70% compressive strain; as well as (iv) similar rate in stress-relaxation. We thereby propose a new hydrocolloidal gel design concept: micro-phase heterogeneity and in turn bulk elasticity are influenced by the aggregation conditions of the auxiliary protein phase, as modulatable by phenolic acids. This mechanism opens new possibilities for fine-tuning elastic texture in support of alternative protein innovation in food processing.