Effect of defined-strain surface starters on the ripening of Tilsit cheese

Young Tilsit cheese is traditionally smeared during ripening using smear liquid from older cheese which facilitates the development of surface flora, but this practice is undesirable from the point of view of hygiene. The objectives of this study were to investigate an alternative to this traditional practice involving a defined-strain surface starter. Two trials of Tilsit cheese were undertaken, In Trial 1, cheese were smeared with a reference smear (RI; old-young smearing) or defined-strain smears, i.e., Mix A (Brevibacterium linens 5 Br5, Microbacterium gubbeenense CA12, Br. casei 047-0399, Corynebacterium casei CA3, Staphylococcus equorum STAPH 2 and Debaryomyces hansenii 6004) or Mix B (as Mix A but C variabile 025-0165 was used instead of C casei CA3). In Trial 2, the cheese were smeared with a reference smear (R2) or defined-strain smears, i.e. Mix C (strains as in Mix A except S. equorum STAPH 2 and D. hansenii 6004 were added to the brine) or Mix D (strains as in Mix C plus S. sciuri STAPH 4 and C variabile 025-0165). Compositional analysis indicated that the surface of the cheese differed from the core due to the action of the smear but that the compositions of the cheese made with the defined strain smear were similar to those made with the reference smears. Levels of pH 4.6-soluble nitrogen, expressed as a percentage of total nitrogen, increased more rapidly at the surface than in the core, reflecting the high level of proteolysis at the higher pH values, but levels were similar in all cheese. Principal component analysis of reverse-phase HPLC chromatograms and data from individual free amino acid analysis separated the surface and core samples of all cheese. Cheese made with the reference smears (R1, R2) were separated from those made with defined strain smear by the end of ripening, reflecting the different proteolytic systems associated with the organisms in the different smears used. (C) 2004 Elsevier Ltd. All rights reserved.