The interaction of apple polyphenols (AP) to staphylococcal enterotoxin A (SEA) in various conditions. (A) The interaction of AP to SEA in various pH conditions. SEA (4.5 μg/mL) and AP (2.5 mg/mL) in 100 μL of Mcilvaine buffer (pH 4.0–8.0) were incubated at 37 °C for 24 h. Following centrifugation, the supernatant was applied to SDS-PAGE and visualized by Western blot analysis. MilliQ water was used as a positive control. * represents p < 0.05 compared to the control, ** represents p < 0.01 compared to the control; (B) The interaction of AP to SEA in gastrointestinal model solution. AP (2.5 mg/mL) and SEA mixture was adjusted to a pH of 2.4 using Mcilvaine buffer, followed by the addition of pepsin from porcine gastric mucosa (final concentration of 0.32%). After three hours, the solution was adjusted from a pH of five to a pH of six to inactivate pepsin, followed by the addition of pancreatin from porcine pancreas (final concentration 0.25%) and bile powder (final concentration 0.4%). After 24 h, the reaction mixture was used for SDS-PAGE and Western blot analysis. MilliQ water was used as a positive control. * represents p < 0.05 compared to the control. Values represent the mean ± SD for three independent experiments.