Commercial food-grade enzymes Alcalase_ 2.4L FG (2.4 AU/g), Savinase_ (16 KNPU/g) and Protamex_ (1.5 AU/g), were kindly provided by Novozymes (Bagsvaerd, Denmark). Corolase
7089 was provided by AB Enzymes GmbH (Darmstadt, Germany). The tripeptide Abz-Gly-Phe(NO2)-Pro was purchased from Cymit- Quimica (Barcelona, Spain). All other chemicals were purchased from Sigma (Barcelona, Spain) unless otherwise specified.