Optimization of red pigmentation and effect of the metabolites produced by Monascus strains on microbial inhibition and colorization in processed ham

摘要

In this study, we tested possibility of replacing nitrite salts, which were always added during the meat product processing, with the metabolites produced by antimicrobial and red pigment producing Monascus strains. We have already shown that Monascus No. 116 strain has the highest antimicrobial activity among the strains isolated from Ang-Khak. Monascus isolate No. 229 was chosen due to its outstanding red pigment producing ability. The red pigment production by No. 229 was highest in the medium containing 8% sucrose, 2% yeast extract, 0.1% K_2HPO_4, 0.5% MgSO_4. Optimum pH and temperature for the red pigment production were pH 6.2 and-30 deg C, respectively. The antimicrobial activity of ethyl acetate extract of Monascus No. 116 culture concentrate was found in spot of R_f value 0.54 on TLC plate using ethyl acetate-acetone-water (4:4:1, v/v/v) as development solvent system. Isolate No. 116 and No. 229 were cultured in a optimal condition for the antimicrobial activity and red pigmentation. The culture concentrates were applied in situ to the production of instantly processed ham. Mixed application of 89 ppm Na-nitrite and 300 ppm of culture broth concentrate of Monascus isolate No. 116 and 500 ppm of red color produced by Monascus isolate No. 229 showed similar results with the single application of 94 ppm Na-nitrite. These results confirmed that the antimicrobial activity and red pigment of Monascus strains might be valuable to replace Na-nitrite salt in meat processing.