In English

Abstract

In recent years, anthocyanins are widely used in food industry as natural dyes and in medicine as compounds with high antioxidant activity. In connection with this, examination of adsorption removal of anthocyanins from extracts of cheap plants containing a lot of these compounds as well as of main and interaction effects which influent on adsorption of anthocyanins is important. In this paper, experiments were conducted according to full factorial experimental design to identify the main and interaction effects of factors and their influence on the removal efficiency of anthocyanins from red cabbage aqueous extracts by bentonite. The factors were investigated at two levels: contact time – 30 and 120 min, temperature – 293 and 323 K, initial anthocyanin concentration – 70 and 130 mg/L, and adsorbent mass – 10 and 25 g/L. The total number of 16 experiments was performed and each experiment was repeated thrice to evaluate an experimental error. Main and interaction effects were analysed using of variance (ANOVA), F-test and P-values to define most important process variables affecting the anthocyanin adsorption. A mathematical model that considers the significant main and interaction effects was suggested. The variance analysis and the statistic data showed that the model was adequate and had high coefficient of determination (R 2 = 0.9954). The mathematical model obtained allows prediction of the removal of anthocyanins from red cabbage aqueous extracts with bentonite. We have found that the contact time and adsorbent mass have the positive effect, but the initial concentration of anthocyanins and temperature as well as two-way interaction “contact time-temperature”, three-way interactions “contact time-initial anthocyanin concentration-adsorbent mass” and “temperature-initial concentration of anthocyanins-adsorbent mass” have the negative effect on the removal of anthocyanins from red cabbage extracts by bentonite. The results indicated that higher removal efficiency of anthocynians from red cabbage aqueous extracts was 95 % at 120 min, 293 K, initial anthocyanin concentration 70 mg/L, and adsorbent mass 25 g/L.