Rhubarb (Rheum rhabarbarum) has been used as a traditional Chinese medicine since ancient times. Today in Europe and America, the value has been recognized as a food material, such as stems for edible use or as a material for dessert manufacturing. Various physiologically active functions of rhubarb have been clarified recently, and various researches are advanced. This study was to investigate the antioxidant activities and quality characteristics of jelly added with 0%, 8%, 16%, 24% and 32% rhubarb stem juices (RSJ). The moisture content and water activity of jelly samples increased significantly with increasing content of RSJ.
The pH was highest in control, and the more RSJ added, the lower the pH was. Hunter color value of the jelly showed that L (lightness) was highest (18.41) in control, but it was not significant in RSJ added samples. A (redness) value was increased significantly with the addition of RSJ. According to texture, the hardness, gumminess, and chewiness was highest in the 0∼8% samples, and decreased by increasing RSJ addition. Springiness was highest in 8∼16% samples. Antioxidant activities measured by DPPH and ABTS radical scavenging activities were significantly higher than those of control and increased respectively according to the concentration of RSJ. DPPH radical scavenging activity results showed 60% activity in 32% sample. ABTS radical scavenging activity was lowest in control and 8∼32% samples showed 70∼80% activity, but it was not significant among 8∼32% samples. The total polyphenol was increased respectively with increasing levels of RSJ. In consumer acceptance test, overall acceptability did not show any significant differences among samples, and the color showed the highest value in 32% sample and the lowest value in 8% sample. There was no significant difference in texture and rhubarb flavor among all samples.
These results suggest that rhubarb juice may be a useful ingredient in gelatin jelly for improvement of quality and antioxidant potential.