Studies on the ripening of Cooleeney, an Irish farmhouse Camembert-type cheese

Abstract

Changes in the main compositional, biochemical and rheological characteristics in the inner and outer parts of two batches of Cooleeney, an Irish farmhouse Camembert-type cheese, were studied throughout ripening (14 weeks). At the end of ripening the average moisture, salt, fat and protein concentrations were 542, 18.6, 270 and 182 g/kg, respectively, and the pH in the inner and outer parts of the cheese were 6.9 and 8.0, respectively. Urea-polyacrylamide gel electrophoresis of the pH-4.6-insoluble fractions of the cheese showed that the coagulant had a strong and early action on α s1 -casein, leading to the formation of α s1 -CN (f24-199) and further degradation products, whereas, β-casein was less degraded than α s1 -casein, although γ-caseins were produced by plasmin action. Peptide profiles by reversed-phase high performance liquid chromatography of ethanol insoluble and soluble fractions exhibited higher concentrations of small hydrophilic peptides in the outer than in the inner part of the cheese as a consequence of higher proteolysis, which was probably due to the action of the surface mycoflora. Fracture force and firmness of the cheese surface decreased throughout ripening, perhaps as a consequence of the increase in pH of cheese and/or breakdown of α s1 -casein. The storage and loss modulus exhibited no significant changes over the measured range, indicating no major disruption of structure; however, both rheological parameters decreased throughout ripening as a consequence of cheese softening.