Production of gamma-aminobutyric acid by cheese starters during cheese ripening.
Nine mixed-strain starters were examined for their abilities to produce gamma-aminobutyric acid. Six commercial starters were found to produce gamma-aminobutyric acid in a skim milk culture. The bacterium that produced gamma-aminobutyric acid was isolated from the mixed-strain starters, identified as citrate-utilizing Lactococcus lactis ssp. lactis (formerly L. lactis ssp. lactis biovar diacetylactis) and designated as strain 01-7. A cell extract showed glutamate decarboxylase activity, for which the optimum pH was 4.7. In pH-controlled cultivation, gamma-aminobutyric acid was generated at pH 5.0 but not above pH 5.5. Cheeses were prepared experimentally using strain 01-7 to determine the relationship between the pH values and the production of gamma-aminobutyric acid during cheese ripening. gamma-Aminobutyric acid increased linearly in the experimental cheeses as the pH of the cheese decreased. Based on these results, gamma-aminobutyric acid was concluded to be produced by the cheese starters during ripening.
Department of Animal Products, National Institute of Animal Industry, Ibaraki, Japan.
M
M
Nomura
H
H
Kimoto
Y
Y
Someya
S
S
Furukawa
I
I
Suzuki
D002611:Cheese / Q000032:analysis / Q000382:microbiology*; D005524:Food Technology; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000302:isolation & purification / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000096:biosynthesis*
D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase