Abstract:To explore the effects of addition amounts of flaxseed gum on soybean protein isolate membrane，the present study prepared a composite membrane by compounding flaxseed gum of different addition amounts（0%，1%，2%，3%，4%，and 5%）with soybean protein isolate.The rheological properties and particle size of the composite film-forming liquid，as well as the cross-sectional microstructure，secondary structure and thermal stability of the composite film were measured and analyzed.The results showed that film-forming liquids with different addition amounts of flaxseed gum were all non-Newtonian fluids.The storage modulus G′and loss modulus G″of the film-forming liquids increased with the increase in the addition of flaxseed gum，and G′was greater than its corresponding G″，indicating that the addition of flaxseed gum made the network structure of the membrane tighter and the maximum thermogravimetric decomposition temperature increased.When the addition amount of flaxseed gum was 3%，protein molecules formed hydrogen bonds with flaxseed gum，and this change made the membrane denser as revealed by the cross-sectional microstructure.When the addition amounts of flaxseed gum were 4% and 5%，the excessive flaxseed gum affected the interaction between protein molecules，causing lines on the membrane section and lowering the maximum thermogravimetric decomposition temperature which was still higher than that of a single soybean protein isolate membrane.