Amino acid is an important ingredient for material modification in the wide spectrum of fields, starts from pollutant removal up to biomedical application. Tofu wastewater has been used as a source of protein containing various amino acids. Herein, we qualitatively and quantitatively analyzed the amino acid contents of tofu wastewater by means of liquid chromatography with tandem mass spectrometry (LC-MS/MS). There were 20 amino acids identified from the tofu wastewater, dominated by L-Tyrosine (25.93%), by L-Cystine (15.75%), L-Glutamic Acid (14.36%), and L-Aspartic Acid (10.38%). The modification of chitosan using the tofu wastewater hydrolysate increased the tensile strength from 1.52 to 1.74 kgf/mm² and adsorption capacity from 1.06 to 2.27 mg/g. Based on the simple additive weighting analysis, the best composite was obtained with composition of 0.975 g, 0.5 mL, and 0.025 g for chitosan, amino acid, and TiO₂, respectively. In conclusion, amino acid contents in tofu wastewater could be used to improve the performance of chitosan-based film composite in removing methylene blue from water.

氨基酸是广泛领域中材料改性的重要成分，从污染物去除到生物医学应用。豆腐废水已被用作含有各种氨基酸的蛋白质来源。在此，我们采用液相色谱-串联质谱法（LC-MS/MS）对豆腐废水中的氨基酸含量进行了定性和定量分析。从豆腐废水中鉴定出20种氨基酸，以L-酪氨酸（25.93%）、L-胱氨酸（15.75%）、L-谷氨酸（14.36%）和L-天冬氨酸（10.38%）为主。使用豆腐废水水解物改性壳聚糖将拉伸强度从1.52提高到1.74 kgf/mm ²和吸附容量从 1.06 到 2.27 mg/g。基于简单的加法加权分析，得到最佳复合物，壳聚糖、氨基酸和TiO _{2 的组成}分别为0.975 g、0.5 mL和0.025 g 。综上所述，豆腐废水中的氨基酸含量可用于提高壳聚糖基复合膜去除水中亚甲基蓝的性能。