M.A. Thesis:

Optimization of consumption levels of date liquid sugar (Shukkari variety) and Stevia rebaudiana extract to improve the physicochemical, sensory and microbial properties of carbonated fruit juice (Apple-Lemon based) using response surface methodology

Carbonated Juice is a product which in a physical method of fruit or concentrated fruit is obtained with drinking water ,authorized food additive and carbon dioxide . The purpose of this research was the substitution liquid date sugar and stevia or apart of sugar in carbonated juice formulation based on apple¬¬-lemon and investigation of its effect on physical ,chemical and sensory properties of the product. In this research central composite design was used for checking the effect of test variable and Design Expert 6.0.6 for statistical analysis. The result showed the interaction of stevia extract and liquid date sugar with increasing of two independent variable, PH level, carbon dioxide ,formalin, dry residue ,density ,Ethanol and Fairy number. L and B color components have increased . In addition, the increasing of stevia extract and decreasing liquid date sugar lead to decreasing of acidity and color component .By the way, the increasing of two independent variable of this research has a suitable effect on deceasing factor of whole sugar, additive sugar and Fairy number. Sensory properties also include of taste, Texture and color with increasing of independent variables level in juice showed improved process for the product quality .The amounts of independent variables in good formulation condition of |juice for stevia extract and liquid date sugar are 0/005,93/570 gr/lit. The result showed,PH3/465,carbon dioxide 4/399,formalin 2/485,Brix11/247,dry residue12/377,acidity0/41,density1/054,Ethanol 0/021,whole sugar 4/925,additive sugar 1/089,decreased sugar 3/820 and Fairy number 99/306.

Keywords: For the result of microbial test , investigation of optimized samples shows the lack of colony in c