comparison of butyric acid concentrations in ordinary and probiotic yogurt samples in iran.

background and objectives: butyric acid has many applications in chemical, food and pharmaceutical industries. applications of butyric acid are as an additive to food, flavorings, varnishes, perfumes, pharmaceuticals and disinfectants. butyric acid concentrations have positive impact on the quality control of milk, yogurt and other probiotic dairy products. the present investigation was undertaken to determine and compare the concentrations of butyric acid (c4) in the ordinary and probiotic yogurt samples by gc method. materials and methods: probiotic yogurt samples were prepared under laboratory scale conditions using two different commercial starters aby1 and 211, while ordinary yogurt samples lacked the probiotic starter cultures. all samples were analyzed in duplicate, for c4 concentrations by gas chromatography after day 1, 2, 10 and 20 of production, during storage at 4ºc. the results were analyzed using anova and duncan test. results: the level of the mentioned fatty acid in aby1 yogurt sample was significantly higher (0.2%) than in 211 samples (0.17%). these values were significantly lower in ordinary yogurt samples and only 0.07% was recorded in these samples on first day of storage which decreased gradually during storage. the level of reduction in the yogurt samples tested during different time intervals was not similar in all the examined samples, and some showed enhanced reduction than other samples. conclusions: compared to ordinary yogurt samples, probiotic yogurt samples used in study showed higher levels of butyric acid with increased shelf life.