Extraction of proteins and preliminary characterization of physicochemical properties in Toona sinensis fruit.

We investigated the extraction of Toona sinensis fruit proteins and preliminarily characterized their physicochemical properties. The results showed that optimal extraction occurred under conditions of pH 10.5, a duration of 40 min, a liquid-to-solid ratio of 25:1, and a temperature of 40°C by an orthogonal design using T. sinensis fruit protein as the index and single factor. The total nitrogen content was 13.8 g/100 g and included 17 different amino acids. The glutamate level was highest at 35.37%, followed by arginine at 15.31%. The isoelectric point of T. sinensis fruit protein was between 6.8 and 10.0 with a typical absorption peak by infrared chromatography. Three protein bands were analyzed using SDS-polyacrylamide gel electrophoresis, with relative molecular weights of 55, 51, and 22 kDa. This study provides a theoretical basis for the comprehensive utilization of T. sinensis fruit by further investigating the biological activity of its proteins.