Small Peptide of Soybean Hydrolysate Is Absorbed More Rapidly than Large Peptide in the Perfused Rat Small Intestine.

The effects of peptide chain length on the absorption of soybean hydrolysates by the rat small intestine were investigated by the perfusion. Two types of soybean hydrolysates, a small peptide (SP; average peptide chain length: 3.2) and a large peptide (LP; average peptide chain length: 5.2), were prepared for this experiment. Krebs-Ringer phosphate buffer (pH 7.0) containing 0.5% (w/v) of either of the two types of soybean hydrolysates was perfused through a 15-cm length of rat jejunum for 70 min. After the perfusion, samples were collected; and the total amount of amino acid was then measured by an amino acid analyzer (Hitachi L-8500) after hydrolysis. The absorption rate of each amino acid was subsequently determined. The absorption rate for glycine, alanine, isoleucine, leucine histidine, arginine, phenylalanine, and proline in SP was significantly greater than that for those in LP. The total amino acid absorption of SP was significantly greater than that of LP. There were no significant differences in the net absorption of water in the buffer solutions of SP and LP. We thus concluded that SP is more greatly absorbed than LP in the intestinal perfusion model of the rat small intestine.