Physicochemical properties and microstructure of soybean protein isolate-vegetable oil complex gels induced by lactic acid bacteria: Effects of vegetable oil types and concentrations

In this work, the physicochemical characteristics and microstructure of soybean protein isolate-vegetable oil complex gels induced by lactic acid bacteria (LSOGs) were studied in relation to various kinds (soybean oil, peanut oil, corn oil) and concentrations (3%–15%) of vegetable oil. The results showed that LSOGs with increased hardness, water holding capacity and storage modulus were successfully obtained by adding vegetable oil, especially soybean oil (followed by peanut oil and corn oil), due to a more uniform and denser network structure was formed, thus allowing more water molecules to bind inside the gel. A 12% soybean oil concentration led to LSOG with the highest hardness (87.52 ± 0.75 g), due to strong hydrophobic interactions and disulfide bonds. The presence of soybean oil as a filler affected the binding between protein molecules, thus forming the more stable gel structure, also as proved by the increased thermal stability. This study might offer theoretical backing for theories about how oil in the soybean protein gel induced by lactic acid bacteria interacted with soybean protein and how to build a fermented emulsion gel system.