The Effect of Coffee Extract on the Growth and Viability of Lactobacillus acidophilus and Bifidobacterium bifidum in Probiotic Milk and Yoghurt

The aim of this study was to determine the suitability of different doses (0, 0.4, 0.8 and 1.2%) of coffee extract on fermentation and survival of Lactobacillus acidophilus and Bifidobacterium bifidum in milk and yoghurt. The produced samples were examined in terms of pH, acidity and microbial count during incubation period and permanence. The number of Lactobacillus acidophilus and Bifidobacterium bifidum in the coffee milk and yoghurts were significantly higher than those in the control milk and yoghurt. Increased concentrations of coffee extract create a favorable taste in milk and yoghurt in the samples containing Lactobacillus acidophilus and Bifidobacterium bifidum. The investigation showed that the yoghurt containing 0.8% coffee extract had superior taste and color. The samples with 0.4% coffee extract in milk and yoghurt had increased viscosity as compared to other samples investigated. The bioability of probiotic bacteria was measured by direct counting method. In day seven, the organoleptic properties of milk and yoghurt were evaluated. Higher sensory scores were obtained by the addition of 0.8% coffee extract in milk and yoghurt. The results suggest that coffee extract promoted the metabolic activity of lactic acid bacteria in milk and yoghurt. According to the findings, addition of coffee extract to milk and yoghurt might be recommended to take the advantage of their beneficial properties on human health attributed to the antioxidant and antimicrobial activities. Coffee extract might also enhance the functional properties of milk and yoghurt with potential therapeutic values for treatments.