HPLC analysis of the pigments produced by the microflora isolated from the'Protected Designation of Origin' French red-smear soft cheeses Munster, Epoisses, Reblochon and Livarot

Red-smear ripened soft cheeses are characterized by their orange-red color which originates from the carotenoids and other pigments produced by ripening bacteria. A total of 114 different bacterial strains, belonging to Brevibacterium linens group, Micrococcaceae and coryneform bacteria, were isolated from four French red-smear ripened soft cheeses with "protected designation of origin" (i.e., Livarot, Reblochon, Munster, and Epoisses). Among the 114 strains, 67 were selected for their orange or yellow color and their methanolic extracts were analysed by HPLC. All orange bacteria showed the same HPLC profile typical of B. linens, which is known to produce the three aromatic carotenoids, isorenieratene, 3-hydroxyisorenieratene, and 3,3'-dihydroxyisorenieratene. Yellow bacteria produced four different chromatographic profiles. Their analysis (retention time and absorption spectrum) revealed strong similarities among three chromatographic profiles and led us to propose that they represent different isomers of the same compound. This study contributes to the characterization of pigments synthesized by the microflora of French red-smear ripened soft cheeses as part of the effort to identify these valuable microorganisms.