Eureka! Institutional Repository

The impact effect of milk type (cow and goat) used and fruit juices (pomegranate and grape) and flower honey addition on the physicochemical, rheological and sensory properties of kefir type products were investigated. Thirty (30) different mixtures of kefir type products were derived using the response surface method (rsm), with the participation rates of the three components ranging from 0% to 15% for pomegranate and grape juices and from 0% to 3% for flower honey. For the preparation of the kefir type samples commercial lyophilized culture and pasteurized full fat (3.5%) cow and goat milk were used. Physicochemical analyses included the determination of pH, acidity (expressed as % lactic acid concentration) and color of the samples. During rheological measurements the flow behavior index and the apparent viscosity of the kefir type products were determined. As far as the sensory evaluation is concerned, the intensity of the color, odor, acidity, sweetness and viscosity (objective characteristics), as well as the overall acceptability of the samples were evaluated. According to the results, pomegranate juice addition caused the lactic acid concentration, sensory acidity and red color intensity of the samples to increase, while it reduced their apparent viscosity. Also, it slightly affected samples flavor and significantly reduced their sweetness. Grape juice adversely affected samples brightness and significantly increased red color intensity and sweetness. It also, caused a slight decrease in pH and acidity, as well as a reduction in the apparent viscosity. The addition of honey reduced the sensory acidity of the samples, while it increased their sweetness and viscosity. Panelists preferred the samples made with cow milk, that had moderate sweetness and low acidity, and also those with moderate sweetness and moderate acidity. According to the statistical analysis, the optimum composition of kefir type products made with honey and fruit juices addition is achieved by using cow milk and adding 1.5% honey, 4.87% pomegranate juice and 5.73% grape juice.