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    Comparison of ?-aminobutyric acid and free amino acid contents of some common varieties of Turkish cheeses
    (Elsevier Sci Ltd, 2022) Ayag, Neslihan; Dagdemir, Elif; Hayaloglu, Ali Adnan
    A total of thirty cheese samples belonging to three varieties (Beyaz, Kasar and Tulum) with different technological traits were analysed for gamma-aminobutyric acid (GABA) and free amino acid (FAA) content. Microbiological and physicochemical status and soluble nitrogen fractions of cheese samples were examined to determine their effects on formation of GABA during ripening. The major FAA were His, Ile, Lys for Beyaz cheeses, Glu, His, Tyr, Ile, Phe, Trp for Kasar cheeses and His, Arg, Tyr, Ile, Leu, Trp for Tulum cheeses. Also, total free amino acid content was higher in Tulum cheeses. The GABA concentration ranged from 0.00 to 83.05 mg 100 g(-1), 1.65-45.79 mg 100 g(-1) and 0.20-21.06 mg 100 g(-1) for Beyaz, Kasar and Tulum cheeses, respectively. Cheese microflora, soluble nitrogen fractions, amino acid concentrations such as Glu and Gln and ripening time/conditions had a significant effect on formation of GABA. (C) 2021 Elsevier Ltd. All rights reserved.
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    Isolation and identification of lactic acid bacteria from artisanal Turkish cheeses, and evaluation of γ-aminobutyric acid (GABA) production potential
    (Elsevier Sci Ltd, 2025) Ayag, Neslihan; Dagdemir, Elif; Cretin, Bulent; Hayaloglu, Ali Adnan
    The aim of this study was to isolate lactic acid bacteria (LAB) from artisanal Turkish cheeses and to determine the strains potentially capable of producing high levels of gamma aminobutyric acid (GABA). A total of 507 LAB were isolated from 45 cheese samples. The cheeses exhibited a microbial diversity, consisting of 16 genera and 30 different species belonging to these genera. The most abundant species in all cheeses was Lacticaseibacillus paracasei. Only 40 of 507 isolates had the GAD gene, and all strains were genetically identified as Lactiplantibacillus plantarum. Two strains (134 and 255) produced GABA in high concentrations, in MRS broth (626.36 +/- 9.86 mg L-1) and skim milk (5.40 +/- 0.47 mg L-1), respectively. The results showed that most of the GABA-producing isolates, especially strains 255 and 134, could be used as starter cultures for the production of functional foods to reduce the risk of disease or improve certain physiological functions.