Modulation of the fibrous structures of high moisture meat substitutes by altering the pH

With the global population steadily rising, the demand for protein is increasing. To meet this demand, plant proteins, precision fermented proteins, and single cell proteins are becoming increasingly important. The extrusion process can be used to produce tasty foods from these proteins, such as meat substitutes and vegan cheese substitutes. To improve the taste and shelf life of these products, salts and acids are often added in the food industry. However, these additives alter the pH and ion concentration, which can affect the structure of proteins and thus influence network formation.
This conference contribution focuses onmeat substitute products from two different vegetable proteins: soy protein isolate and vital wheat gluten. These proteins differ in their network formation mechanism. Soy protein isolate forms a physical network, while gluten forms a chemical network stabilized by disulfide bonding.
To investigate the influence of altering the pH, materials and parameters are screened using a closed cavity rheometer, followed by extrusion trials at pH 7.36 – 4.14 for SPI and pH 5.83 – 3.37 for gluten. The resulting extrudates are analyzed optically and mechanically, and protein solubility is tested in a reducing buffer. ... mehrAt decreasing pH, the complex viscosity of SPI is increasing, the generated network is becoming stronger, and the cross-linking density is growing. For gluten, a decreasing pH results in altered reaction kinetics, the resulting network is more deformable, and the cross-linking density is decreasing. Solubility tests show that no additional covalent bonds are formed with SPI. With gluten, however, the polymerization reaction is inhibited and fewer disulfide bonds are formed. For both protein systems, the addition of acid results in less pronounced meat-like structures. These new findings are helping to develop plant-based extrudates with improved taste and texture.