Use of principal component analysis to evaluate the physical properties ofMahon cheese

The texture, colour and water activity of the seven existing types of Mahon cheese, manufactured under the Mahon cheese Appellation of Origin, were st udied using eight physical variables. Four of the types are industrially ma nufactured [fresh (less than 10 days of ripening), half-ripened (2-5 months of ripening), ripened (5-10 months of ripening) and old-ripened (more than 10 months of ripening)] and three are traditionally manufactured (half-rip ened, ripened and old-ripened). ANOVA, Tukey's multiple range test and prin cipal component analysis (PCA) were used. Mahon cheeses from different ripe ning periods exhibited significant differences in water activity and yellow ness values (P<0.001). PCA reduced the eight physical variables to two inde pendent components, which accounted for 84.4% of the total variance. The fi rst principal component (PC1) separated cheeses characterised by high water activity, high springiness values and slight yellowness from those with hi gh hardness and puncture force; PC1 therefore distinguished among samples f rom different ripening periods. Cohesiveness, chewiness and gumminess were highly correlated in the second principal component, which could be interpr eted as an index of cohesiveness.