Reduction of limonin in tangerine Citrus reticulata Blance Juice by Beta-cyclodextrin polymer

Abstract

This study aims to use ß-cyclodextrin polymer (ß-CD polymer) as an absorbent for the reduction of limonin in Thai tangerine juice and to compare its effectiveness in the batch and column processes. The juice of tangerine fruits from an orchard in Prathumtani province, were extracted and preheated at 70℃ for 10 minutes. The limonin was separated from the juice by means of solid phase extraction (SPE) technique using Extra Sep C-18 column, eluted with acetonitrile, and quantitated by reverse phase HPLC. The sensitivity of the method was 0.3 ppm limonin at C.V. 3.70%. The accuracy was 83% and precision ±0.94. Accuracy of the method, however, varied with the flow rate and limonin load, but had no effect on precision of the data. In the batch debittering processes, using initial limonin concentration of 7.76 ppm, the highest % limonin reduction was 81 at the condition of 5 g% ß-CD polymer, 60 minutes and 6℃. there was no significant difference of % limonin reduction using No.3 and No.5 mixing speed (magnetic stirrer, Heidolph MR3003). Acceptable level of limonin was observed with 3 g% ß-CD polymer for 30 minutes at room temperature (~30℃). Greater limonin reduction (94%) was observed in the column process with 3 g% ß-CD polymer, 10 ml bed volume, flow rate 0.35 ml/min, and room temperature (~30℃). In term of limonin adsorption capacities, the batch and column process were 0.17 and 0.27 mg limonin/g ß-CD polymer. In addition, the debittering processes did not cause apparent change of the juice. Using 5.6 g% XAD-16 in column debittering at the same condition of ß-CD polymer column, the limonin adsorption capacity was 0.18 mg limonin/XAD-16.