Bioactive whey protein hydrolysate

Abstract

The invention relates to a partial hydrolysate of when protein which contains bioactive peptides but does not have a bitter flavour. The hydrolysate is carried out using selective enzymes which produce the active peptides and is terminated at a degree of hydrolysis before substantial bitter flavours are created. There are also described novel peptides and a method of reducing systolic blood pressure through the administration of the peptides.

1 . A process for preparing a soluble whey protein hydrolysate containing bioactive peptides which comprises: 
 i) hydrolysing a whey protein-containing substrate with at least one heat labile protease, at a temperature of between about 20° C. and 65° C. at a pH of about 6 to about 8 when said protease is a neutral protease, at a pH of about 3 to about 5 when said protease is an acid protease, and at a pH of about 5 to about 10 when said protease is an alkaline protease, and    ii) terminating said hydrolysis when a degree of hydrolysis of no greater than 10% has been reached by deactivating said protease under conditions which produce a water soluble hydrolysate that can be spray dried.    
     
     
         2 . A process as claimed in  claim 1  wherein said substrate is sweet whey or sweet whey protein concentrate.  
     
     
         3 . A process as claimed in  claim 1  wherein said protease is selected from the group consisting of Protease P6, Protease A, Protease M, Peptidase, Neutrase, Validase and AFP 2000.  
     
     
         4 . A process as claimed in  claim 1  wherein said hydrolysis terminating step comprises heat deactivation.  
     
     
         5 . A process according to  claim 4  wherein said heat deactivation comprises heating said hydrolysate for up to ten seconds to a temperature up to 95° C.  
     
     
         6 . A process as claimed in  claim 1  wherein said hydrolysis terminating step comprises altering the pH of said whey protein-containing substrate to a pH at which said protease is not active.  
     
     
         7 . A process as claimed in  claim 6  wherein said hydrolysis terminating step includes heat deactivation.  
     
     
         8 . A process as claimed in  claim 1  wherein said hydrolysis terminating step comprises subjecting said hydrolysate to ultrafiltration with an ultrafiltration membrane having a nominal molecular weight cutoff in the range of 10-500 kDa.  
     
     
         9 . A process as claimed in  claim 1  wherein said enzyme is immobilised on an inert support during said hydrolysis step.  
     
     
         10 . A process as claimed in  claim 9  wherein said inert support is Roehn Eupergit, carrageenan particles, chitosan particles or any other suitable inert support material.  
     
     
         11 . A process as claimed in  claim 1  wherein the degree of hydrolysis is about 3-5%.  
     
     
         12 . A process as claimed in  claim 1  wherein the substrate also contains lactose, in an amount of about 5% by weight or higher.  
     
     
         13 . A process as claimed in  claim 12  wherein said lactose content is about 10% by weight or higher.  
     
     
         14 . A process as claimed in  claim 12  wherein the amount of lactose present in the substrate is up to about 30% by weight.  
     
     
         15 . A process as claimed in  claim 12  wherein the amount of lactose present in the substrate is up to about 50% by weight.  
     
     
         16 . A process as claimed in  claim 12 , wherein the substrate is also treated with lactase and/or β-galactosidase, either before, during or after the whey protein hydrolysis, to hydrolyse the lactose to galactose and glucose and synthesize galacto-oligosaccharides.  
     
     
         17 . A process as claimed in  claim 1  wherein the hydrolysate so prepared contains one or more of the bioactive peptides selected from the group consisting of AFE, LFSH (SEQ ID NO: 1), ILKEKH (SEQ ID NO: 2), LIVTQ (SEQ ID NO: 3), MKG, LDIQK (SEQ ID NO: 4), VF, ALPMH (SEQ ID NO: 5), VTSTAV (SEQ ID NO: 6), LHLPLP (SEQ ID NO: 7), LVYPFPGPIPNSLPQNIPP (SEQ ID NO: 8) and LFRQ (SEQ ID NO: 9).  
     
     
         18 . A process according to  claim 1  which includes the additional step of testing said water soluble hydrolysate for bio-activity selected from the group consisting of angiotensin converting enzyme (ACE) inhibiting activity and reduction of in vivo blood pressure.  
     
     
         19 . A process according to  claim 18  wherein the bio-activity tested for is angiotensin converting enzyme inhibiting activity.