Optimization of ultrasound supported extraction conditions of antioxidant and phenolic compounds of purple onion shells

The aim of this study is to determine the optimization conditions for the extraction of red onion skin. The Desing-Expert program was used for the extraction of red onion peel. Four independent variables were chosen for the extraction of red onion peel. These variables were determined as liquid-solid solvent ratio, alcohol ratio, temperature and time. Experiment design was created with the Design-Expert program. 27 samples were extracted from the experimental design created. Total phenolic content analysis, total monomeric anthocyanin analysis and betaine analysis were performed on these samples. The results of the analyzes performed on 27 samples were re-entered into the Design-Expert program. The best 3 solution samples were selected from these analysis results. The first selected solution, for example, extraction conditions; It is in 105 minutes, 57 liquid-floor, 40 ℃ and 95 ethanol concentration. The second chosen solution example; It is a concentration of 98 ethanol in 110 minutes, 60 liquid-floor, 54 ℃. The third chosen solution example; It is 100 minutes, 55 liquid-floor, 60 ℃ and a concentration of 97 ethanol. 3 solutions selected from the Desing-Expert program was re-analysis of the amount of phenolic matter, total monomeric anthocyanin analysis and betalein analysis was performed. In addition, except for these analyzes; Dry material analysis, water activity analysis, water and oil holding capacity analysis, stack density analysis and carr index analysis were also performed. Total amount of phenolic substance in the analysis of the solution examples analysis values were found in the range of 1084.6-1423.8 mg GAE/100 g. Total Monomeric anthocyanin analysis values were found in the range of 1346.7-2398.1 mg/kg. Betalein analysis values were found in the range of 1001.84-1137.41 mg/L. In color analysis values, the value L was found in the range of 11.32-14.76, the A values are between 9.21-14.77 and B values were found in the range of 1.97-3.46. Dried matter analysis values were found in the range of 89.46-98.82. Water activity analysis values were found in the range of 0.20-0.52. Water and oil holding capacity analysis values were found in the range of 0.40-0.64 and the oil holding capacity analysis values were found in the range of 0.99-1.31. Stack intensity analysis was found in the range of 0.09-0.23 g/ml. Carr index values were found in the range of 33.34-50.05. In this study, the solution sample that gives the most suitable values from the optimization conditions from the three solution conditions selected using the Desing-Expert program was selected in 105 minutes, 57 liquid-floor, 40 ℃ and 95 ethanol concentration was selected. This condition of optimization can be used in the processing of onion peel and studies.