Optimization of ionic gelling encapsulation of red beet (Beta vulgaris L.) juice concentrate and stability of betalains

Abstract

Red beet (Beta vulgaris L.) with high betalain compounds possesses antioxidant properties beneficial in human's health and is a substitute to artificial colorants in the food industry. But the stability of the natural pigments should be concerned therefore encapsulation is a promising tool to overcome the saturation problem of the color. One of the encapsulation methods which is alginate/calcium-chloride ionic gellation was applied to beet juice concentrate (70 °Brix). Optimum conditions for encapsulation were determined by Response Surface Methodology, Box-Behnken Design where the red beet concentration was found as 14.81% sodium-alginate concentration as 1.7%, and dipping time as 5 min. The effects of the 6 weeks of storage at 25 ± 1 °C were also investigated. During the 6 weeks of storage, a* value of capsules has decreased gradually. Starting from the 4th week, changes in betalain content were found statistically insignificant (p > 0.05). At the end of the storage period, 79.48% of the betalain was preserved. Additionally, the characterization of capsules was maintained by scanning electron microscope (SEM) images, total dry matter, total phenolic content, antioxidant capacity, release test for characterization of capsules, potential usage in model food, and sensory analysis were examined and evaluated. These results showed that ionic gelation is a promising method to obtain stable betalain capsules that have the potential to be used as a natural colorant.