酱油二次沉淀严重影响其外观质量和商品价值。本研究以大豆低压长时（0.24 MPa/18 min）蒸煮工艺为对照，采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和基质辅助激光解吸附电离串联飞行时间质谱（MALDI-TOF/TOF MS）等方法研究了大豆高压短时（0.54 MPa/14 min）蒸煮工艺对酱油二次沉淀蛋白和二次沉淀生成量的影响。实验结果表明大豆球蛋白G4中的B3亚基（20 ku）和G1中的A1a亚基（35 ku）是酱油二次沉淀蛋白的主要成分，采用大豆高压短时蒸煮工艺制备的酱油（样品）比其对照酱油中B3亚基减少65.38%，样品中A1a亚基被完全降解；样品中二次沉淀含量比其对照减少72.69%。同时，采用大豆高压短时蒸煮工艺可提高酱油原料蛋白质利用率9.37%、氨基酸态氮14.14%、总氮10.74%、总糖22.36%、还原糖27.87%和无盐固形物12.38%（p<0.05）。因此，采用大豆高压短时蒸煮工艺可显著提高酱油二次沉淀蛋白降解率、减少酱油二次沉淀生成量和提高酱油滋味物质含量，同时改善酱油外观质量和滋味。

Secondary precipitates affect the appearance and commercial value of soy sauce adversely. Therefore, to investigate ways to minimize secondary precipitates in soy sauce, the content of secondary precipitate protein and the amount of secondary precipitates in soy sauce made from soybean prepared using high-pressure and short-duration steaming (0.54 MPa/14 min) were compared with the same parameters in soy sauce made from soybean prepared using low-pressure and long-duration steaming (0.24 MPa/18 min) as a control. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry were used to analyze the secondary precipitate proteins and secondary precipitates in the soy sauces. The B3 subunit of glycinin G4 (20 ku) and the A1a subunit of glycinin G1 (35 ku) were the main protein components of the secondary precipitates. The B3 subunit content in soy sauce prepared using the soybean steamed at high pressure for a short time (hereinafter, the sample) was 65.38% lower than that of the control, whereas the A1a subunit in the sample was completely degraded. The secondary precipitate content in the sample was also reduced, by 72.69% relative to the control level. Additionally, the application of high pressure and a short time to steam the soybean enhanced the rate of utilization of proteins in the raw materials by 9.37% and led to the following increases in the soy sauce: amino acid nitrogen: 14.14%; total nitrogen: 10.74%; total sugars: 22.36%; reducing sugars: 27.87%; and salt-free solids: 12.38% (p<0.05). Therefore, the adoption of high pressure and a short duration for the soybean steaming process can significantly enhance the rate of secondary precipitate protein degradation, reduce the content of secondary precipitates, and increase the content of taste compounds in soy sauce, leading to simultaneous improvements in the appearance and taste of the product.

中山市重大科技专项项目（2018A1007）