Abstract:With soy protein isolate （SPI） and theanine as the main raw materials，the theanine-SPI-based composite tofu was prepared by the traditional salt brine tofu processing procedure. The texture characteristics，moisture distribution，cooking loss，swelling rate，and microstructure of the composite tofu were analyzed by a texture analyzer，a low-field nuclear magnetic resonance imaging analyzer，and a scanning electron microscope.The application potential of the composite tofu was evaluated based on the slow-release behavior of tea flavor substances （geraniol，linalool，and benzoic acid）. The results showed that compared with the pure SPI-based tofu，the 0.10% theanine-SPI-based composite tofu showed reduced release rates of geraniol，linalool，and benzoic acid. Theanine （0.10%） improved the texture properties of SPI-based tofu，enhancing the elasticity，chewiness，and swelling rate （p＜0.05）. Furthermore，it improved the gel network structure，reduced the cooking loss（p＜0.05），and made the moisture distribution more uniform. Theanine，as a quality improver，effectively improved the overall quality of SPI-based tofu.