Creation of plant-based meat analogs: Effects of calcium salt type on structure and texture of potato protein-alginate composite gels

Due to environmental and ethical concerns with current meat production practices, there is a need to create plant-based meat analogs that accurately simulate the textural attributes of animal-derived meat. This study therefore assessed the impact of different insoluble calcium salts on the structural and rheological properties of plant protein-polysaccharide hydrogels formed via internal gelation. Potato protein (10 wt%) was used as a sustainable source of heat-set gelling proteins, whereas sodium alginate (1 wt%) was used as a sustainable source of ion-set gelling polysaccharides. Initially, CaCO3, Ca3(PO4)2, or CaHPO4 were used to crosslink the alginate in the protein-polysaccharide mixtures at ambient temperature by slowly releasing Ca2+ ions as the pH was reduced due to the action of D-glucono-δ-lactone (GDL). When the same amount of GDL and calcium were used, the pH trends, as well as the appearance and texture, were similar for Ca3(PO4)2 and CaHPO4 induced gels, whereas CaCO3 induced gels showed different characteristics, which was mainly attributed to the release of CO2 bubbles during the dissociation of this insoluble calcium salt. At the same calcium and GDL concentration, the gel strength increased in the following order: CaCO3 < Ca3PO4 < CaHPO4. This change in gel strength was mainly related to differences in the pH-time profiles produced by the dissolution of the different calcium salts. Micro-computed tomography analysis showed that the textural characteristics were related to the porosity of the composite hydrogels produced. When the final pH of all the samples was set at pH 5.5 by controlling the GDL concentration, the CaCO3 induced hydrogels had a higher gel strength than the Ca3(PO)4 and CaHPO4 induced ones. However, CaCO3 induced gels also released a large amount of CO2 bubbles, which disrupted the gel structure both before and after the heating process. Overall, our results showed that the pH, appearance, structure, and texture of potato protein/alginate hydrogels can be controlled by manipulating the type of insoluble salt and the amount of added GDL used. These potato protein-alginate hydrogels may therefore be suitable for creating meat analogs in the plant-based food industry.