Research Progress on Formation and Removal of Beany Flavor in Soy Protein-based Meat Alternatives

Plant-based meat, recognized as a sustainable alternative to animal meat, offers significant benefits in terms of nutrition and environmental sustainability. Soy protein, one of the primary raw materials for plant-based meat production, tends to develop a beany off-flavor during the extrusion process, which negatively affects consumer acceptance. This study provided a comprehensive review of the formation mechanisms of volatile beany off-flavor compounds, such as aldehydes, alcohols, ketones, and furans, in soy protein-based meat alternatives. The findings suggested that the beany flavor primarily arises from the oxidative degradation of residual lipids in soy protein and added fats during the extrusion process, a reaction influenced by factors such as fatty acid composition, lipid content, and extrusion parameters. Additionally, the Maillard reaction and Strecker degradation also contribute to the formation of these beany flavor compounds. The adsorption and diffusion behaviors of these volatile compounds within the protein matrix are governed by a combination of steric hindrance effects, due to the dense structure of plant-based meat, and the interaction between the volatiles and the protein. Current research indicated that individual deodorization techniques have limitations. Instead, an integrated approach that combines raw material pretreatment (e.g., ultrasound and radiofrequency technology), extrusion process flavor optimization (e.g., the addition of flavor enhancers), and post-extrusion flavor enhancement may lead to more effective reduction of off-flavors. This study aims to provide a theoretical foundation for the development of plant-based meat products with reduced beany flavors, ultimately contributing to advancements in product quality within the industry.