M.A. Thesis:

optimization of rhubarb alcohol-free beer formulation using response surface mythology

Abstract This study was conducted to use rhubarb to produce Malt Beverage. Rhubarb's extract was distillated by juicer and pasteurized. Then it was prepared in four different volume proportions of 5%, 10%, 15% and 20% and added to the formulation of malt beverage (malt extract, sugar, malt flavor, citric acid, carbonated water and malto-dextrin). During 60 days keeping in refrigerator, the PH testing, Brix, turbidity, color intensity, total phenolic compounds, total antioxidant compounds, pH, carbon dioxide, ash, reducing sugar, the amount of ethanol, density, sensory and microbiological tests were analyzed on Samples. The results of pH measurements represent a decline during the first 30 days and then increase over time in the beer. Acidity, gas storage, the amount of phenolic compounds, antioxidant activity, the amount of alcohol and reducing sugar levels over time was significantly reduced in malt beverage. The maintenance time did not significant effect on color intensity and Brix but turbidity, ash, density and mesophilic aerobic bacteria have increased by passing time till 30th day and then decreased till day 60, respectively. Results count mold during storage for all treatments showed no mold, but yeast count increased with time until the end of the maintenance period. According to the data of sensory assessment for all features except the color of caring, rhubarb extract (5%) was the best treatment and the color factor, control sample was more accepted. Keywords: rhubarb, beer (malt beverage), formulation, sensory analysis (assessment), phenolic compounds

Keywords: Keywords: rhubarb, beer (malt beverage), formulation, sensory analysis (assessment), phenolic compou