Effect of mechanical interaction on the hydration of mixed soy protein and gluten gels

Abstract

Mixed gels of plant proteins are being investigated for use as meat analogues. Juiciness is an important characteristic for the acceptability of meat analogues. The juiciness is assumed to be governed by the hydration properties, or water holding capacity, of the gel (WHC). We analysed the WHC of single-phase gels of respectively soy protein and gluten by applying Flory-Rehner theory. This enabled us to describe the WHC of more the complex mixed gels. The WHC of mixed soy protein - gluten gels is shown not to be a linear combination of their constituents. At high volume fractions, soy forms a continuous network and swells similarly to pure soy without being hindered by gluten. However, increasing gluten content leads to a gradual decrease in soy swelling. This is due to the mechanical interaction between soy and gluten. We propose that gluten-rich gels have a continuous gluten network that entraps soy and hinders its swelling. The elastic moduli of the gluten network were extracted from WHC data, and are in reasonable agreement with experimentally determined moduli. A better understanding of the effect of mixed gel composition on WHC is valuable for the development of the next generation meat analogues.

Functionality of Ingredients and Additives in Plant-Based Meat Analogues

“…In addition, many of the functional properties of the proteins as swelling, viscosity, gelation, emulsification, and foaming are affected by the availability of water in the food system and the degree of interaction with the biopolymers [ 274 , 275 ]. This is important for specific meat analogue application such as in sausage-type products where water is needed for the emulsification process.…”

Thermo-mechanical processing of plant proteins using shear cell and high-moisture extrusion cooking

“…Stretching of the network during hydration will result in an additional elastic contribution to the free energy and must be taken into account by using Flory-Rehner theory instead. This approach was used to describe the water partitioning in mixtures of gluten with a protein isolate from either soy (Cornet, van der Goot, et al 2020), pea, or fababean. Although the water distribution in polymer mixtures can be measured and predicted, the water distribution during thermo-mechanical treatment is currently unknown.…”

“…However, since the gels were prepared at a much lower temperature (95 C) than the extrudates (170 C), direct comparison of these results is difficult. Apart from the cooling rate, also the protein concentration influences the modulus of SPI gels, with a higher concentration resulting in a higher modulus (Cornet, van der Goot, et al 2020).…”

“…The presence of two (or more) separate phases in bio-polymer mixtures is broadly accepted and has been studied extensively using a range of experimental and theoretical tools (Grinberg and Tolstoguzov 1997;Polyakov, Grinberg, and Tolstoguzov 1997;Tolstoguzov 1993;Cheftel, Kitagawa, and Queguiner 1992;Grabowska et al 2014;Dekkers, de Kort, et al 2016;Schreuders et al 2020;Cornet, van der Goot, et al 2020). The group of Tolstoguzov showed that protein-polysaccharide mixtures generally tend to phase-separate (Grinberg and Tolstoguzov 1997;Tolstoguzov 1993), and that protein-protein blends do not mix at concentrations relevant to extrusion and shear cell processing (Polyakov, Grinberg, and Tolstoguzov 1997).…”

Starch in Plant‐Based Meat Replacers: A New Approach to Using Endogenous Starch from Cereals and Legumes

“…The mechanism behind fiber formation in these materials is still debated in the literature. [68,[85][86][87]96,103,[108][109][110][111][112][113][114][115][116] Next to process parameters such as dry matter content, processing time, temperature, and pressure, the origin and composition of the ingredients are of utmost relevance as well. Many studies focus on protein-protein interactions and polymerization, [114,117,118] but also the influence of carbohydrates is investigated.…”