Evaluation of physicochemical and sensory properties of apple juice drink containing soluble dietary fiber of flaxseed

Enrichment of fruit juices with dietary fiber can not only improve the final quality of the drink, but also improve the health of the consumer. Among oilseeds, flaxseed is rich in alpha-linolenic acid, soluble dietary fiber and lignan. In this study, dietary solution fiber of flaxseed was extracted by three methods of alkaline, enzymatic and ultrasonic extraction and extraction efficiency, water and oil storage capacity and colorimetry of the extracted soluble fibers were evaluated. The results showed that the soluble fiber extracted by ultrasonic method with the highest extraction efficiency, water holding capacity, oil holding capacity and having the highest L * index and the lowest a * and b * index, was selected as the optimal sample.  The optimal sample of soluble fiber was added to apple juice drink at the levels of 0.5%, 1%, 1.5%. Physicochemical and sensory properties of apple juice drink during 30 days of storage at first day, the fifteenth day and the thirtieth day was evaluated. The results showed that the use of flaxseed soluble fiber had a significant effect on brix, dry matter, pH, turbidity, sensory properties (taste, color, aroma, texture, general acceptance) of apple juice drink (p≤0.05). Rheological test showed that all apple juice treatments containing soluble flaxseed fiber had a non-Newtonian behavior. The apple juice drink containing 0.5% of soluble dietary fiber obtained the highest score of sensory properties. Turbidity of apple juice drink containing 0.5% soluble dietary fiber was less than other samples. Therefore, apple juice drink containing 0.5% of soluble dietary fiber selected as an optimal treatment. By adding soluble dietary fiber of flaxseed to apple juice can produce a new drink with favorable characteristics.