Effect on Benzoic Acid Production of Yoghurt Culture and the Temperatures of Storage and Milk Heat Treatment in Yoghurts from Cow, Goat and Sheep Milk

Yoghurts from cow, goat and sheep milk were produced and stored under defined conditions to monitor the influence of various factors on the benzoic acid content as determined by Ultra High Performance Liquid Chromatography (UHPLC). The highest level of benzoic acid was found in sheep yoghurt (43.26 +/- 5.11 mg kg(-1)) and the lowest in cow yoghurt (13.38 +/- 3.56 mg kg(-1)), with goat yoghurt (21.31 +/- 5.66 mg kg(-1)) falling in between. Benzoic acid content did not show statistically significant variation until the second and third weeks of storage, and the dynamics of this variation varied depending on the type of yoghurt. The yoghurt culture containing different strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus also affected the contents of benzoic acid. Further, the different storage temperatures (2 and 8 degrees C) as well as the temperatures used to milk heat treatment before yoghurt production (80, 85 and 90 degrees C) affected the amount of benzoic acid in different types of yoghurts.