compounds present in the volatile profile of each strain (Bosset and
Gauch, 1993). Hence, to interpret how the volatile profiles discriminated
between the strains, PCA was performed and the results are presented
in Fig. 2 principal component analyses. The first two PC's explained
49% of the variation. Fig. 2a shows the scores of the samples and
Fig. 2b shows the loadings of the compounds. Three main groups
were identified (Fig. 2a): group 1 contained the uninoculated milk
sample, group 2 consisted of the control strains IL1403, HP and
303, and group 3 consisted of all the plant lactococci isolates. PCA
analysis of the volatile profiles also clearly separated the control
dairy strains from the plant lactococci isolates. This latter group was
associated with a higher level of most of the volatile compounds detected
suggesting the ability of the plant isolates to produce a wider variety