Method for preparing tryptophan rich peptides

Abstract

Described is a method for selectively isolating tryptophan containing peptides from an aqueous peptide mixture, including the steps of controlling the pH of the aqueous peptide mixture to 4.0-6.0, forming a precipitate of tryptophan containing peptides, and isolating the precipitated peptides. The aqueous peptide mixture is preferably obtained by enzymatic cleavage at acidic pH of a protein source. Further, peptides having a Trp content of 8-15 w/w % and the use thereof as a food additive and as an active ingredient in a medicament are described.

1 . Method for -selectively isolating tryptophan containing peptides from an aequeous peptide mixture, comprising the steps of: 
 a) controlling the pH of the aequeous peptide mixture to 4,0-6,0, forming a precipitate of tryptophan containing peptides, and    b) isolation of the precipitated peptides.    
     
     
         2 . Method according to  claim 1 , wherein step a) is carried out at a temperature of below 20° C.  
     
     
         3 . Method according to any of the preceding claims, wherein the aequeous peptide mixture is prepared by enzymatic cleavage of a protein source.  
     
     
         4 . Method according to  claim 4 , wherein the protein source is cleaved by one or more acid proteases or cysteine proteases, preferably chosen from the group, consisting of pepsin, papain or bromelain, or a mixture of two or more thereof.  
     
     
         5 . Method according to  claim 5 , wherein the protein source is cleaved by pepsin at a pH of between 1,5-3,5, preferably between 2-3.  
     
     
         6 . Method according to any of the preceding claims, wherein the peptide mixture is desalted.  
     
     
         7 . Method according to any of the proceeding claims, wherein the tryptophan containing peptides are derived from whey protein, preferably from α-lactalbumin enriched whey protein.  
     
     
         8 . Tryptophan enriched peptides mixture, obtainable by the method according to any of the claims  1 - 7 , having a tryptophan content of 8-15 w/w % on peptide basis.  
     
     
         9 . Peptide mixture according to  claim 8 , having a Trp/(Phe+Tyr) ratio of at least 0,900 on weight basis.  
     
     
         10 . Peptide mixture according to  claim 8  or  9 , having a Trp/(Phe+Tyr+Leu+Val+Iso+Met) ratio of at least 0,300 on weight basis.  
     
     
         11 . Peptide mixture according to any of the claims  8 - 10  for use as food ingredient.  
     
     
         12 . Peptide mixture according to any of the claims  8 - 10  for use as active ingredient in a medicament.  
     
     
         13 . Peptide mixture according to any of the claims  8 - 10  for use in a human or veterinary medicament as active ingredient for inducing the synthesis of serotonin, tryptamine, nicotinic acid or melatonin.  
     
     
         14 . Peptide mixture according to any of the claims  8 - 10  for use as active ingredient in a medicament against malignant cell growth.  
     
     
         15 . Food product, comprising the peptide mixture according to any of the claims  8 - 10 .