Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products

Authors: RICHTER, JANA - Washington State University; WATANABE, PRESTON - Washington State University; BERNIN, JOSHUA - Washington State University; Smith, Brennan; MITACEK, RACHEL - Washington State University; GANJYAL, GIRISH - Washington State University

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2024
Publication Date: 5/28/2024
Citation: Richter, J., Watanabe, P., Bernin, J., Smith, B., Mitacek, R., Ganjyal, G. 2024. Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products. Journal of the Science of Food and Agriculture. https://doi.org/10.1002/jsfa.13569.
DOI: https://doi.org/10.1002/jsfa.13569

Interpretive Summary: This study investigates the impact of chemical compounds, such as cysteine, sodium metabisulfite, and glutathione, on the texture and chemical interactions of high moisture meat analog (HMMA) products processed through extrusion. The experiment involved blending wheat protein with different levels of the compounds and extruding them at varying temperatures. The results show that the inclusion of reductants significantly influenced the structure of the extrudates, enhancing cross-linking between the proteins and improving the flow behavior of the protein melt. Notably, high fibrousness was achieved when cysteine or sodium metabisulfite was added at a concentration of 0.50%. These findings contribute to a better understanding of the texturization mechanism in HMMA products and have implications for their production and quality control.

Technical Abstract: o High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins. Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5'g'kg-1 was extruded at three different temperatures (115, 140, and 165'°C) using a co-rotating twin-screw extruder. The feed rate (85'g'min-1), the moisture content (600'g'kg-1), and the screw speed (300'rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index. The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0'g'kg-1. In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products.