Microbiological, physicochemical properties and biogenic amine contents of the strained yoghurts from Turkish local markets
Thirty three strained yoghurt samples were collected from local open markets in different provinces of Turkey (Afyon [AF], Aydın [AY], Burdur [B], Isparta [I] and Muğla [M]). Physicochemical and microbiological properties, as well as biogenic amine content, were examined in each of the samples. The dry matter (17.90 to 26.44%), fat (5.51 to 10.44%), ash (0.65 to 1.48%), lactic acid (1.69 to 2.05 g l-1), salt (0.61 to 1.68%), pH (3.52 to 3.94), protein (5.73 to 8.57%) and syneresis (1.67 to 9.22%) of samples differed as indicated. The mean of the lactobacilli counts ranged from 6.63 to 8.35 Log10 CFU g-1, lactococci ranged from 7.16 to 8.02 Log10 CFU g-1, while streptococci and propionic acid bacteria ranged from 6.71 to 7.27 and 5.60 to 8.38 Log10 CFU g-1, respectively. All the yoghurts were contaminated with fungi and coliforms at levels above the acceptable limits, indicating insufficient process hygiene and also raising concerns of consumer safety. Tryptamine is the only biogenic amine determined in all yoghurt samples. Cadaverine, putrescine, tyramine and b-phenylethylamine were not detected in any of the samples.
Key words: Strained yoghurt, physicochemical properties, biogenic amine, tryptamine.