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Response Surface Methodology, an approach to predict the effects of a lactoperoxidase system, Nisin, alone or in combination, on Listeria monocytogenes in skim milk
Author(s) -
Boussouel N.,
Mathieu F.,
Benoit V.,
Linder M.,
RevolJunelles A. M.,
Millière J. B.
Publication year - 1999
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1999.00707.x
Subject(s) - nisin , lactoperoxidase , listeria monocytogenes , incubation , chemistry , thiocyanate , response surface methodology , skimmed milk , incubation period , microbiology and biotechnology , food science , chromatography , bacteria , biochemistry , peroxidase , biology , enzyme , antimicrobial , genetics
Experimental designs using Response Surface Methodology (RSM) were used to determine effects and interactions of Nisin (0–200 IU ml −1 ), pH values (5·4–6·6), incubation time (0–36 h or 0–144 h) and the lactoperoxidase‐thiocyanate‐hydrogen peroxide system (LPS) on Listeria monocytogenes CIP 82110 in skim milk, at 25 °C. The LPS varied from level 0–2; LPS at level 1 consisted of lactoperoxidase (35 mg l −1 ), thiocyanate (25 mg l −1 ) and H 2 O 2 , which was supplied exogenously by glucose‐oxidase (1 mg l −1 ) and glucose (0·2 g l −1 ); LPS activity was dependent on LPS level and incubation time. In the presence of LPS at level 1, a bacteriostatic phase was followed by growth, whereas at a higher level, a bactericidic phase was observed. Nisin response was time‐ and pH‐dependent. Nisin was bactericidic at acidic pH values and for a short incubation time (12 h) only; then, a re‐growth phase was observed. Nisin and LPS in combination gave an original response which lacked the transitory bactericidal effect of Nisin and had a continuously bactericidal affect, leading to 10 cfu ml −1 of L. monocytogenes at 144 h; the response was greatly affected by incubation time. Predicted values were in good agreement with experimental values. Response Surface Methodology is a useful experimental approach for rapid testing of the effects of inhibitors.