Partial identification of water-soluble peptides released at early stages of proteolysis in sterilized ovine cheese-like systems: influence of type of coagulant and starter.
Cheese-like systems were manufactured from sterilized ovine milk, using crude aqueous extracts of Cynara cardunculus or cardosin A isolated therefrom as clotting agent. The effect of adding a commercial starter culture was also assessed. The impact of the type of coagulant used during the initial 24 h of proteolysis was evaluated via separation of peptides in the water-soluble extracts by reverse-phase HPLC, followed by partial sequencing via Edman degradation. Cardosin A accounted for most events of primary proteolysis. The major cleavage sites were Phe105-Met106 in kappa-casein, and Leu127-Thr128, Ser142-Trp143, Leu165-Ser166, and Leu190-Tyr191 in beta-casein. The starter culture did not play an active role during the initial stages of ripening.
Silva
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Escola Superior de Biotecnologia, P-4200-072 Porto, Portugal.
Malcata
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D000818:Animals; D016282:Aspartic Acid Endopeptidases; D002364:Caseins / Q000378:metabolism; D002611:Cheese / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D012085:Chymosin; D031942:Cynara / Q000201:enzymology*; D005260:Female; D005511:Food Handling / Q000379:methods*; D006868:Hydrolysis; D008894:Milk Proteins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D010455:Peptides / Q000032:analysis* / Q000378:metabolism; D010940:Plant Proteins; D012756:Sheep; D012995:Solubility; D013242:Sterilization; D014867:Water; D000067816:Whey Proteins
D002364:Caseins; D008894:Milk Proteins; D010455:Peptides; D010940:Plant Proteins; D000067816:Whey Proteins; D014867:Water; C025350:rennet; D010447:Peptide Hydrolases; D016282:Aspartic Acid Endopeptidases; C097455:aspartic proteinases, Cynara cardunculus; D012085:Chymosin