RESUMO

Naringin and limonin are the two main bitter compounds of citrus products such as grapefruit juice. The aim of this investigation was to evaluate the reduction in both bitter components simultaneously using a combined biochemical and physical approach. The proposed strategy was based on the use of heterofunctional supports with glyoxyl groups that allow for the covalent immobilization of naringinase, which hydrolyses naringin and alkyl groups that allow for the adsorption of limonin. The supports were butyl-glyoxyl agarose (BGA) and octyl-glyoxyl agarose (OGA), which were characterized in terms of aldehyde group quantification and FTIR analysis. The optimal pH and temperature of free and immobilized enzymes were assessed. The maximum enzyme loading capacity of supports was analyzed. Debittering of grapefruit juice was evaluated using soluble enzyme, enzyme-free supports, and immobilized catalysts. Enzyme immobilized in BGA reduced naringin and limonin concentrations by 54 and 100%, respectively, while the use of catalyst immobilized in OGA allowed a reduction of 74 and 76%, respectively, obtaining a final concentration of both bitter components under their detection threshold. The use of OGA biocatalyst presented better results than when soluble enzyme or enzyme-free support was utilized. Biocatalyst was successfully applied in juice debittering in five repeated batches.

Assuntos

Citrus paradisi , Limoninas , Adsorção , Estabilidade Enzimática , Enzimas Imobilizadas/química , Flavanonas , Hidrólise , Complexos Multienzimáticos , Sefarose , beta-Glucosidase

RESUMO

ABSTRACTThe use of cell and plant tissue culture techniques to produce economically important active metabolites has been growing. Among these substances are total limonoid aglycones, which are produced by "pera" orange (Citrus sinensis (L.) Osbeck, Rutaceae) and have received considerable attention because of their anticancer actions. The main objective of the present study was to analyze and compare the levels of limonoid aglycones in seeds, callus cultures (originating from seeds), callus cultures (originating from hypocotyls), cell suspensions from hypocotyls cells, and cell suspensions from cotyledons. The cell cultures or C. sinensis were obtained by inoculating two strains of callus in MS medium supplemented with 2.0 µM 2,4-dichlorophenoxyacetic acid, 7.0 µM benzyl aminopurine, and 3% (w/v) sucrose in the dark. The highest concentrations of limonoid aglycone that were obtained were observed in cotyledon cell lines (240 mg/100 g dry weight) that were produced on day 21 of culture and hypocotyl cell lines on day 7 (210 mg/100 g dry weight). Explants of different origins under the same culture conditions had different limonoid aglycone content. The present results may suggest strategies for enhancing the productivity of biologically important limonoid aglycones and investigating the complex pathways of these secondary metabolites in plant tissue cultures.