| 摘要 |
PROBLEM TO BE SOLVED: To provide protein decomposition product including a large amount of angiotensin-converting enzyme inhibiting active peptide which can be prepared by a simple method, easily handled as an edible product, and expected to have an excellent blood pressure lowering effect, from extraction residue (used tea leaves) produced by extraction of tea leaves or used tea leaves with water or hot water.SOLUTION: The steps are sequentially performed of extracting tea leaves or used tea leaves with alkali aqueous solution, adding acid to the produced extract to have a pH of 2 to 5 for precipitation of a protein fraction, decomposing the produced protein fraction with protease for stopping the enzyme reaction, and allowing the enzyme reaction liquid to have a pH of 2 to 5 for separating a peptide fraction soluble in acidic aqueous solution and an unreacted protein fraction through precipitation of the unreacted protein fraction. In the decomposing step using protease, neutral endopeptidase and acidic exopeptidase are employed to function. |
