effect of extract from tragopogon graminifolius dc. on properties sensory, shelf life and the viscosity rate yogurt

background & aim: herbal extracts contain the important useful natural compounds. in the food industry are great important due to properties flavoring and aroma's, as well as delaying the corruption and are widely used as condiments, flavorings, preservatives and antioxidants. experimental: the extract of tragopogon graminifolius was added to milk prepared for yogurt production before packing and adding starter at different concentrations of 500,1000, and1500 parts per million, and produced yogurt was assessed of physical, chemical, sensory and rheological ,within 21 days and at specified time intervals. results & discussion: results indicated that adding extracts salsify has been effective on chemical properties of yogurt. the extract constant acidity and increased shelf life and water-holding capacity (whc). in addition, the extract reduced among of water in yogurt and undesired on the rheological properties of yogurt such as viscosity. recommended applications / industries: according to the results of the experiments of physical, chemical, and rheological, concluded the extract from tragopogon graminifolius was most desirable efficiency of the process changes acidity, ph, whc, the amount of water coming out of yogurt.