Food Engineering
Nazanin Bazazian; Akram Arianfar
Abstract
Introduction: Doogh is a fermented milk drink mixed with water and a little salt. The production and exportation of dough as a native Iranian fermented beverage has grown steadily in recent years. One of the disadvantages that causes corrosion and increases doogh deterioration is the spoilage caused ...
Read More
Introduction: Doogh is a fermented milk drink mixed with water and a little salt. The production and exportation of dough as a native Iranian fermented beverage has grown steadily in recent years. One of the disadvantages that causes corrosion and increases doogh deterioration is the spoilage caused by the activity of molds and yeasts. The common method for increasing shelf life of food (such as doogh) is drying by using spray dryer that eventually lead to reducing the volume, costs of carrying and easy usage. The objective of this study was to produce a doogh powder by spray drying method and investigate the effect of Alyssum homolocarpum seed gum on its physicochemical properties. Material and Methods: In this study, yogurt (1.5% fat), salt, distilled water, maltodextrin (GPC brand), and Alyssum homolocarpum seed gum were used. Alyssum homolocarpum seed gum was cleaned and the foreign particles were separated. The whole grain gum was extracted using distilled water in a water-to-seed ratio of 30 to 1 with a pH of about 8 and a temperature of 48°C and dried at 70°C in a vacuum oven and then powdered. Brine (7% salt) was prepared with boiled distilled water at 80°C. After dissolution, a certain amount of Alyssum homolocarpum seed gum was added (at concentrations of 0, 0.05, 0.1, 0.15, 0.2% separately). The solution was stirred for 10 minutes with a magnetic stirrer at 60°C. After complete dissolution, 40g of yogurt (1.5% fat with pH=4.1) was added to gum solution. The final volume of doogh was at 100g. To completely dissolve the particles, a magnetic stirrer with a speed of 2000 rpm for 15 minutes at 60°C was used. The temperature was then reduced to 20°C and the final product was packed in 500 ml bottles. Doogh was dried using a spray dryer in optimal conditions, feed intake flow of 44.5 ml/ min and drying temperature of 190°C. The physicochemical properties of dough powder such as pH, acidity, moisture content, dry matter, solubility, dispersability, and serum separation as well as glass transition temperature and particle size were determined. Doogh treatments consisted of 0.05, 0.1, 0.15 and 0.2% containing Alyssum homolocarpum seed gum and also a control sample. All the experiments were performen in triplicate. The results were analyzed as means± standard deviation (SD). Thus, the data were determined using the software SPSS (2013). Statistical differences were analyzed by variance (ANOVA) and Duncan’s multiple range test (P values <0.05). Results and Discussion:The results showed that by increasing the Alyssum homolocarpum seed gum , moisture and serum separation were decreased and acidity, dry matter, solubility, dispersability ,particle size and glass transition temperature were increased. With increasing gum concentration from 0.05 to 0.1 and from 0.15 to 0.2%, the acidity increased significantly (P<0.05).The rate of dehydration of samples containing different percentages of gum after three weeks showed that the use of Alyssum homolocarpum seed gum significantly reduced serum segregation. The results showed that by increasing the concentration of gum, the particle size of the dough powder was significantly reduced (p<0.05).With the increase in the amount of gum, the rate of diffusion increased significantly (P<0.05).With increasing gum concentration and decreasing moisture, the glass transfer temperature of the powder samples increased. The control sample had the lowest and the 0.2 gum treatment had the highest glass transfer temperature (P<0.05).
