46F-18 |
The enhancement of in vitro protein digestibilty by the additon of bile salts |
D. R. CLARK1, R. D. Phillips1, and Y. H. Tuan2. (1) Food Science & Technology, University of Georgia, 1109 Experiment Street, Griffin, GA 30223, (2) Department of Restaurant Management, Kuang Wu Institute of Technology and Commerce, Taipei, Taiwan Bile salts are the physiological detergents used by the human body in the digestion of lipids, in which they emulsify and form micelles, which allow for stabilization and transport of lipid molecules for further digestive processes. During digestion, hydrophobic cores of proteins may be exposed, suggesting that bile salts may be effective in the digestion of proteins as well. The objective of this study was to determine the ability of bile salts to enhance the in vitro digestion of casein, sorghum, and cowpea. A 50/50% mixture of sodium cholate and sodium deoxycholate was used to test the effectiveness of bile salts on the in vitro digestion of casein, sorghum, and cowpea. An enzymatic digestion with pepsin and pancreatin (PPD) was used to investigate this hypothesis. After a 15-minute pepsin digest at pH 1.9, pH was adjusted to 7.5 and a pancreatin solution was added to continue hydrolysis of proteins. In each experiment, three samples: substrate alone, enzyme alone, and a combination of substrate and enzyme were subjected to the pH adjustment/incubation sequence. In one series, 0.05% bile salts were added along with the pancreatin. In the other, bile salts were omitted. All samples were digested for 6 hours. Trichloroacetic acid was used to precipitate large protein molecules. The samples were centrifuged and the supernatant analyzed for % nitrogen values in order to calculate the total protein digested. Casein digestibility was increased by 28% in the presence of bile salts. Similar trends were evident in the digestibility of sorghum. Cowpea digestion was increased to a lesser extent. This suggests that bile salts have a positive impact on the protein digestion. Including bile salts in in vitro protein digestibility assays improve assay results, pointing the way to an improved method for assessing protein quality.
Session 46F, Nutrition
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