Casein hydrolyzate, process for producing the same and use thereof

Abstract

The present invention relates to a casein hydrolysate containing free amino acids and in vivo indigestible peptides having minimally suppressed in vivo enzymatic digestibility, and expected to express functions, such as hypotensive effect, in living organism, and to a method for preparing such a hydrolysate, and use thereof. The casein hydrolysate of the present invention contains free amino acids and peptides, such as in vivo indigestible peptides including Xaa-Pro and Xaa-Pro-Pro, obtained by hydrolyzing animal milk casein to have an average chain length of not longer than 2.1 in terms of the number of amino acid residues, and has ACE inhibitory activity or hypotensive effect.

1 . A casein hydrolysate comprising free amino acids and peptides obtained by hydrolyzing animal milk casein to have an average chain length of not longer than 2.1 in terms of the number of amino acid residues.  
     
     
         2 . The casein hydrolysate of  claim 1 , wherein said peptides comprises in vivo indigestible peptides consisting of dipeptides having a sequence Xaa-Pro and tripeptides having a sequence Xaa-Pro-Pro, and wherein a content of said dipeptides having a sequence Xaa-Pro is not lower than 5 wt % of a total amount of the free amino acids and the peptides in the hydrolysate, and a content of said tripeptides having a sequence Xaa-Pro-Pro is not lower than 1 wt % of a total amount of the free amino acids and the peptides in the hydrolysate.  
     
     
         3 . The casein hydrolysate of  claim 1  for food additive or medicine.  
     
     
         4 . The casein hydrolysate of  claim 2 , wherein said dipeptides having a sequence Xaa-Pro comprises Ile-Pro, Glu-Pro, Arg-Pro, Gln-Pro, Met-Pro, and Tyr-Pro, and said tripeptides having a sequence Xaa-Pro-Pro comprises Ser-Pro-Pro, Ile-Pro-Pro, and Val-Pro-Pro.  
     
     
         5 . A method for preparing a casein hydrolysate of claim  1 , comprising the step of (A) hydrolyzing animal milk casein to have an average chain length of not longer than 2.1 with a group of enzymes capable of digesting animal milk casein into a casein hydrolysate having an average chain length of not longer than 2.1 in terms of the number of amino acid residues.  
     
     
         6 . The method of  claim 5 , wherein said group of enzymes are extracellular enzymes derived from  Aspergillus oryzae.    
     
     
         7 . The method of  claim 5 , wherein said hydrolyzing is performed in a one-step reaction with said group of enzymes.  
     
     
         8 . The method of  claim 5 , wherein said group of enzymes is group of enzymes (X) comprising peptidases capable of cleaving a peptide bond Pro-Xaa.  
     
     
         9 . The method of  claim 8 , wherein said group of enzymes (X) further comprises at least one of metalloproteases and serine proteases.  
     
     
         10 . The method of  claim 8 , wherein said group of enzymes (X) further comprises at least one of neutral protease I, neutral protease II, and leucine amino peptidases.  
     
     
         11 . The method of  claim 8 , wherein said group of enzymes (X) are extracellular enzymes derived from  Aspergillus oryzae.    
     
     
         12 . The method of  claim 8 , wherein said peptidases capable of cleaving a peptide bond Pro-Xaa are a group of enzymes having isoelectric points in an acid region.  
     
     
         13 . The method of  claim 5 , wherein in said step (A), a casein concentration in hydrolyzing said animal milk casein is 3 to 19 wt %, and a ratio of said group of enzymes to animal milk casein is not lower than 1/100 by mass.  
     
     
         14 . An agent having angiotensin converting enzyme inhibitory activity or hypotensive effect comprising a casein hydrolysate of  claim 1  as an active ingredient.