Objective: To establish test model of stability of different protein to digestion in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF).
Methods: The component of SGF and SIF being from the United States Pharmacopeia, the stability of various proteins were tested. The concentration of protein in SGF/SIF was 0.5mg/ml. At intervals of 0s, 15s, 30s, 60s, 2min, 4min, 8min, 15min, 30min and 60min, the samples were taken out. According to the results of SDS-PAGE, the stability of various proteins to digestion in SGF/SIF was observed.
Results: The experiment showed that trypsin inhibitor from soybean, beta-lactoglobulin A from bovine milk and beta-lactoglobulin B from bovine milk were stable within 60min in SGF. Peanut lectin was digested within 8min. Most soybean lectin was digested within 8min, but the degraded fragments still existed. Ovalbumin, ovomucoid, BSA, soybean lipoxygenase and potato acid phosphatase were digested within 15s. The results in SGF were not consistent with the results in SIF. Trypsin inhibitor from soybean, beta lactoglobulin A from bovine milk, beta-lactoglobulin B from bovine milk, BSA, ovalbumin, ovomucoid, soybean lectin and peanut lectin were stable for 60min in SIF. The degraded fragments of soybean lipoxygenase and potato acid phospatase exited within 60min.
Conclusion: Different proteins showed different stability to SGF/SIF. According to the difference, model of evaluating the stability of protein to SGF/SIF was established.