title: pH-stat vs. free-fall pH techniques in the enzymatic hydrolysis of whey proteins.
abstract: Enzymatic hydrolysis of a commercial whey protein isolate (WPI) using either trypsin or Protamex® was compared using controlled (pH-stat) and uncontrolled (free-fall) pH conditions. pH-stat control at the enzyme's optimum value led to a more rapid rate of WPI hydrolysis by trypsin, while the opposite was the case when Protamex® was used. Furthermore, the choice of alkaline solution used to maintain constant pH during pH-stat experiments appeared to affect the reaction rate, being higher when KOH is added to the reaction mixture instead of NaOH. It would appear that potassium may play a role as co-factor or activator for the activity of this particular protease preparation. Although pH-stat techniques are usually considered to yield better hydrolysis kinetics, these findings suggest that the response of proteolytic enzyme preparations to static or free-fall pH control should be checked in advance, particularly when undertaking large scale production of WPI hydrolysates.
authors.affiliation: Teagasc and Food for Health Ireland (FHI), Moorepark Food Research Centre, Fermoy, Co. Cork, Ireland.
authors.forename: Ayoa
authors.initials: A
authors.lastname: Fernández
authors.affiliation: Teagasc and Food for Health Ireland (FHI), Moorepark Food Research Centre, Fermoy, Co. Cork, Ireland. Electronic address: phil.kelly@teagasc.ie.
authors.forename: Phil
authors.initials: P
authors.lastname: Kelly
mesh_terms: D006868:Hydrolysis; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D000067816:Whey Proteins
keywords: Enzymatic hydrolysis; Free-fall pH; Protease; Whey proteins; pH-stat