1 n hydrochloric acid

Simulated gastric juices (SGJs) were prepared by adding pepsin from porcine (Sigma-Aldrich, St. Louis, MO, USA) to achieve 2,000 U/mL in 0.85% sterile saline, and the pH was adjusted to 2.5, 3, or 3.5, with 1 N hydrochloric acid (Daejung Chemicals & Metals Co., Ltd., Siheung, South Korea). SGJ was sterilized by filtering using a 0.22-μm filter membrane (Minisart NML-Sartorius, Göttingen, Germany). Sterile saline (pH 7) was used as the control. The range of pH was set to 2.5 to 3.5 because the pH of ingested food is known as pH 3, and the exposure time was set to 1 to 2 h because the recommended time of the gastric phase was 2 h (24 (link), 25 (link)). The amount of enzyme was determined based on the method described by Minekus et al. (25 (link)). All the digestive juices were prepared prior to testing.

Simulated gastric juices (SGJs) were prepared by adding pepsin from porcine (Sigma-Aldrich, St. Louis, MO, USA) to achieve 2,000 U/mL in 0.85% sterile saline, and the pH was adjusted to 2.5, 3, or 3.5, with 1 N hydrochloric acid (Daejung Chemicals & Metals Co., Ltd., Siheung, South Korea). SGJ was sterilized by filtering using a 0.22-μm filter membrane (Minisart NML-Sartorius, Göttingen, Germany). Sterile saline (pH 7) was used as the control. The range of pH was set to 2.5 to 3.5 because the pH of ingested food is known as pH 3, and the exposure time was set to 1 to 2 h because the recommended time of the gastric phase was 2 h (24 (link), 25 (link)). The amount of enzyme was determined based on the method described by Minekus et al. (25 (link)). All the digestive juices were prepared prior to testing.

Sodium selenite (Na₂SeO₃; Sigma–Aldrich, St. Louis, MO, USA), L-ascorbic acid (C₆H₈O₆, Sigma, USA), D-(+)–glucose (C₆H₁₂O₆, Sigma, USA), sodium hydroxide beads (NaOH, Daejung, Seoul, Korea), and 1N- hydrochloric acid (HCL, Daejung, Korea) were used. All chemicals were reagent-grade and used without further purification.