title: Hydrolysis of caseins and formation of hydrophilic and hydrophobic peptides by wild Lactococcus lactis strains isolated from raw ewes' milk cheese.
abstract: OBJECTIVE
  To investigate the hydrolysis of alphaS1-, alphaS0-, betaB-, betaA1- and betaA2-caseins by 32 wild lactococci of different randomly amplified polymorphic DNA (RAPD) patterns, isolated from raw ewes' milk cheese, and the production of hydrophilic and hydrophobic peptides from whole casein by those strains.
  
  
  RESULTS
  Most strains hydrolysed all caseins, and degraded beta-caseins to a larger extent than alphaS-caseins, when the proteolytic activity of whole cells was determined by capillary electrophoresis. Higher levels of hydrophilic than of hydrophobic peptides were produced from whole casein by all strains, according to reverse-phase high performance liquid chromatography analyses.
  
  
  CONCLUSIONS
  Cell envelope proteinases of most lactococci isolated from raw ewes' milk cheese were CEPII, CEPII/III or CEPIII (classification of Exterkate et al. 1993). A negative correlation was found between degraded alphaS- and beta-caseins and a highly positive correlation between hydrophilic and hydrophobic peptides.
  
  
  CONCLUSIONS
  Fast acid-producing lactococci from raw ewes' milk cheese have considerable and diverse caseinolytic activities. Their peptide production patterns do not reveal serious risks of bitter-flavour defect in cheeses if used as components of dairy starters.
authors.affiliation: Departamento de Tecnología de Alimentos, INIA, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Morales
authors.forename: E
authors.initials: E
authors.lastname: Fernández-García
authors.forename: P
authors.initials: P
authors.lastname: Gaya
authors.forename: M
authors.initials: M
authors.lastname: Medina
authors.forename: M
authors.initials: M
authors.lastname: Nuñez
mesh_terms: D000818:Animals; D002364:Caseins / Q000378:metabolism*; D002611:Cheese / Q000382:microbiology*; D010450:Endopeptidases / Q000378:metabolism; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D013294:Lactococcus lactis / Q000201:enzymology* / Q000302:isolation & purification; D008892:Milk / Q000382:microbiology*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D012756:Sheep
chemical_list: D002364:Caseins; D010455:Peptides; D010450:Endopeptidases