Abstract
Objectives
This study investigated the occurrence of Strecker degradation during in vitro digestion.
Methods
Casein was first incubated with artificial gastric fluid containing porcine pepsin and HCl (pH = 2) for 60 min. After adjusting pH to 7 with sodium hydroxide, casein gastric digesta was then incubated with artificial intestinal fluid containing porcine pancreatin (pH = 7) for 120 min. Digesta samples were collected at 0, 10, 20, 30, and 60 min of gastric digestion, and then 10, 20, 30, 60, and 120 min of intestinal digestion. Free amino acids and aldehydes in digesta samples were analyzed by the liquid chromatography-mass spectrometry analysis.
Results
Multiple aldehydes were detected in gastric digestion samples, and their concentrations were further increased by intestinal digestion. Among them, isovaleraldehyde, isobutyraldehyde, phenylacetaldehyde, and acetaldehyde, are the Strecker degradation products of leucine, valine, phenylalanine, and alanine, respectively. Without digestive enzymes, casein incubation did not produce Strecker aldehydes.
Conclusions
In vitro digestion of proteins can produce Strecker aldehydes.
Funding Sources
This research was partially supported by the Agricultural Experiment Station project MIN-18-125 (C. C.) from the United States Department of Agriculture (USDA).