Development of an Optimal Formulation for Flavored Doogh-Based Soft Drink Using Response Surface Methodology and Evaluate the Resulting Powder

Doogh is a fermented drink that is consumed in Iran and other Middle Eastern countries. Due to the increased awareness of the harmful effects of carbonated drinks, Doogh consumption have been increased considerably because of its nutritional benefits. Using healthy and antibacterial flavoring agents such as lime extract and mint distillate, in certain concentrations, can reduce the viability of traditional yoghurt starters and be a good alternative to industrial thermal processes (in heated Doogh). In addition, the powder of these products under certain conditions will contribute to ease maintenance and transportation.
In the present study, Doogh-based soft drink optimized with lime extract (0-6% v/v) and mint distillate (0-4% v/v) for sensorial and antioxidant properties, using response surface methodology (RSM) and studied during refrigerated storage at 5°C. Soft drink powder was produced by spray dryer in different input air temperatures to increase the product’s shelf life and weight loss.
The results showed that the the best model fitted on the sensory total score and IC50 was quadratic. The addition of 3.382% (v/v) lime extract and 2.484% (v/v) mint distillate to drink led to the highest sensory total score and lowest IC50 (the highest antioxidant activity). The optimized formulated drink was stable for 42 days with non-significant loss of sensory quality (p>0.05). For long term storage and production of powder by spray dryer, input hot air temperature at 170°C caused the highest percentage of solubility and sensory acceptability. The resulting powder also had acceptable moisture content, water activity (aw) and color total changes (ΔE).
The consumption of Doogh-based products with traditional flavors, might be a strategy to increase the variety of soft drink market. The results of present study showed that Doogh formulated with 3.382% (v/v) lime extract and 2.484% (v/v) mint distillate had desirable sensorial and antioxidant properties. Moreover, the novel Doogh-based drink was transformed to powder that have high solubility and sensory score using spray drier at 170°C.