Proteolysis as a function of distance from surface to centre in a smear-ripened Irish farmhouse cheese

This study focused on proteolysis in an Irish farmhouse smear-ripened cheese by serial slicing (0.41 mm/slice) the first 2 cm from surface towards the centre of the cheese. Ureapolyacrylamide gel electrophoretograms confirmed higher proteolysis in the outer layers than at the centre. Free amino acid (FAA) analysis confirmed decrease in proteolytic activity from surface to centre. Peptides produced at depths 0.41 mm and 20.5 mm were 720 and 427 from αs1-casein; 691 and 337 from αs2-casein; 807 and 453 from β-casein; 180 and 109 from κ-casein. The study confirms higher proteolytic activity at surface due to action of enzymes of the smear microbiota, than at the centre of cheese and identified the agents responsible for production of many peptides

Proteolysis in Irish farmhouse Camembert cheese during ripening

Proteolysis in an Irish farmhouse Camembert cheese was studied during 10 weeks of ripening. Urea‐polyacrylamide gel electrophoresis of pH 4.6‐insoluble fractions of cheese showed the degradation of caseins, initially due to the action of chymosin and plasmin and later due to Penicillium camemberti proteinases. Proteolytic specificities of Penicillium camemberti proteinases on the caseins in milk hydrolysates were determined and 64, 6, 28, and 2 cleavage sites were identified in αs1‐, αs2‐, β‐, and κ‐casein, respectively. Proteolysis in cheese was studied and peptides produced were determined and compared to the cleavage specificities of Penicillium camemberti proteinases. Regions most susceptible to proteolysis were 1–40, 79–114, and 168–199 in αs1‐casein; 42–79 and 97–116 in αs2‐casein; 40–57, 101–125, 143–189, and 165–209 in β‐casein; and 31–81 and 124–137 in κ‐casein. The present study describes in detail the proteolytic action of proteinases from Penicillium camemberti in Camembert cheese during ripening. Practical applications: Camembert cheese is a major international cheese variety, made in many countries around the world. The ripening of the cheese involves many biochemical changes and this study provides new information on peptides produced during ripening. Penicillium camemberti is an important mold used in the production of this type of cheese and detailed information is provided on the action of its enzymes on the caseins. Data reported in this study furthers the understanding of the ripening of Camembert cheese

Proteolysis in Danish blue cheese during ripening

Proteolysis in Danish blue cheese was studied during 9 weeks' ripening. Levels of pH 4.6-soluble N as a percentage of total N increased from 7.2% to 25%, indicating extensive proteolysis. Urea-polyacrylamide gel electrophoretograms confirmed the extent of proteolysis through chymosin and plasmin action early in ripening, but later the action of Penicillium roqueforti proteinases became apparent. The proteolytic specificity of Penicillium roqueforti PR-R proteinases on αS1- and β-casein was determined in a model system. Regions most susceptible to proteinase action in αS1-casein were 6–40, 69–99, 124–147 and 155–199, with a total of 91 cleavage sites identified; regions in β-casein susceptible to proteolysis were 43–87, 101–119, 161–185 and 192–209 with a total of 118 cleavage sites identified. A large number of peptides was identified cheese extracts during 9 weeks ripening, principally from αS1-casein regions 1–40, 105–136 and 150–176 and β-casein regions 6–14, 46–68, 101–140 and 193–209

Patterns of proteolysis in Danish blue, Camembert, smear-ripened and Cheddar cheeses

Patterns of proteolysis in Danish blue, Camembert, smear-ripened and Cheddar cheeses The overall aim of this thesis was to investigate patterns of proteolysis in Cheddar, Danish blue (normal and treated), Camembert and smear ripened cheeses at different stages of ripening. Proteolysis in Danish blue was studied during 9 weeks of ripening, specificities of Penicillium roqueforti proteinases on the caseins in milk hydrolysates were determined with a total of 91 and 118 cleavage sites identified in s1- and -casein, respectively. Proteolysis in an Irish farm-house Camembert cheese was studied during 10 weeks of ripening, specificities of Penicillium camemberti proteinases on the caseins in milk hydrolysates were determined and 64, 6, 28 and 2 cleavage sites were identified in s1-, s2-, - and -casein, respectively. Proteolytic, physico-chemical and lipolytic properties of Danish blue cheeses made from partially (73%) or fully homogenised milk (200 L) with or without whey cream were determined at 4 weeks and 8 weeks of ripening. The study showed that incorporation of the whey cream did not cause any major difference to the compositional, proteolytic or lipolytic properties of Danish blue cheese. Proteolysis in an Irish farmhouse smear-ripened cheese was studied by serial slicing (0.41 mm/slice) the first 2 cm from surface towards the center of the cheese. Peptides produced at depths 0.41 mm and 20.5 mm were 720 and 427 from αs1-casein; 691 and 337 from αs2-casein; 807 and 453 from-casein; 180 and 109 from -casein, respectively. The study confirmed higher proteolytic activity at the surface due to action of enzymes of the smear microbiota than at the center of the cheese. Secondary proteolytic changes of the chymosin-derived peptides s1-CN (f1-23) and -CN (193-209) were investigated in Cheddar cheeses made using single strains of Lactococcus lactis subsp. cremoris HP and SK11 during 6 months of ripening and proteolytic specificities of the cell-envelope proteinases of these strains on the caseins were determined. A large number of peptides were identified from mass spectrometric analysis of the soluble extracts of the individual cheesees and highest values of relative intensity from the mass spectrometric analyses were used to plot the cleavage sites that can be used for further understanding of peptides, cleavage site and similar research