~ 204 ~  Journal of Pharmacognosy and Phytochemistry 2016; 5(2): 204-206 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2016; 5(2): 204-206 Received: 23-01-2016 Accepted: 25-02-2016 Maya Zhelyazkova Sofia University, Faculty of Mathematics and Informatics, Department of Probability, Operations Research and Statistics,,st. Stara planina bl.2 vh. A, ap.11, Yambol, Bulgaria IRA Taneva Trakia University - Stara Zagora, Faculty of Technics and Technologies, Department of Food Technology, 8600, Yambol, Bulgaria; 38, Graf Ignatiev Str. Correspondence: Maya Zhelyazkova Sofia University, Faculty of Mathematics and Informatics, Department of Probability, Operations Research and Statistics,,st. Stara planina bl.2 vh. A, ap.11, Yambol, Bulgaria Statistical modeling of the process syneresis of the production of yogurt with water extract of Rosa canina Maya Zhelyazkova, IRA Taneva Abstract The role of antioxidants on the health of the human body begins to be explored in depth in the second half of the 20-th century with the discovery of the so-called free radicals. In this paper we explore the effect of Rosa canina as a natural antioxidant. The aim of the study is to find the dependency between percent water extract of Rosa canina and the amount of separated whey in preparation of yogurt. The process of separating the whey is crucial for good quality yogurt- texture, acidity, formation of the flavor of the milk. The results of statistical analysis show that 5 % water extract of the fruits of Rosa canina does not affect significantly the amount of separated whey in the process syneresis. Keywords: yogurt, Rosa canina, whey, one-sample ttest 1. Introduction The role of antioxidants on the health of the human body begins to be explored in depth in the second half of the 20th century with the discovery of so-called free radicals. Free radicals are atoms or molecules that are formed in the human body as a result of the processes of oxidation of essential nutritional ingredients. The negative effects of free radicals is called "oxidative stress". Antioxidants provide effective protection against free radicals. For example, Vitamin C is an antioxidant that is necessary for the growth and repair of tissues and for improving the immunity function of the adrenal gland. Wild rose, with its rich chemical composition is widely used in the manufacture of food products as a functional nutrition. Fruits of Rosa Canina can be used both in fresh and dried form but also in the form of extracts. Briar are 20 to 40 times richer in vitamin C than red tomatoes and lemons, and about 300 times more potent compared to apples. The content of L- ascorbic acid (vitamin C) is highest in the fruit flesh - 546 mg/100g in Rosa damascene and 2200mg/100g in Rosa canina [1] . Antioxidant activity of briar is mainly due to the synergistic combination of polysaccharides and organic acids, phenolic antioxidant compounds (glycosides, kaempferol), acids (galolova, cinnamic, ellagic) anthocyanins and tannins [2, 3] . 2. Materials and Methods In our research we used wild dog rose (Rosa canina L.), of 2012 year collected from the area of the town of Kyustendil. Fruits were grinded by laboratory mill to a particle size of 2-4 mm and extracted with water under hydro: 1: 20. The data consists of a quantity of whey obtained in four samples: the first sample was control, second, third and fourth samples are respectively the addition of 5, 10 and 15% water extracts of rose hips. The process of separating the whey is crucial for good quality yogurt- texture, acidity and formation of the flavor of the milk. The aim of the study is to find the dependency between percent water extract of Rosa canina and the amount of separated whey in preparation of yogurt. The variable of interest is the amount of whey for each sample. The null hypothesis is that the mean of the difference between the four samples is equal to zero. For one sample t-test [5] , we use samples which are formed by the all possible differences: a control group - 5% water extract of rose hips;10% water extract of rose hips- 5% water extract of rose hips; 15% water extract of rose hips - 5% water extract of rose hips; control group – 10 % water extract of rose hips; control group – 15% water extract of rose hips; 10% water extract of rose hips – 15 % water extract of rose hips.