Ionic Liquids As Green Extractors for Achievement of Carotenoids from Orange Peel

Abstract

Orange is among the most produced and consumed fruits in the world, and Brazil is responsible for 50% of world production of orange juice. However, the high production of orange juice involves generation of large amounts of residue from orange peel, which in turn is a source of antioxidants compounds such as carotenoids that fight against reactive oxygen species, reflecting in reducing the incidence of cancer, inflammation, cataracts, macular degeneration, and cardiovascular diseases in humans. The application of ionic liquids (I.L.) in extraction processes is a viable alternative, which follows the principles of green chemistry, minimizing contamination and optimizing the achievement of these natural compounds. Because they are molten salts, the properties of interest may be adjusted to the needs required in the extraction process, which enable their application for achievement of carotenoids (hydrophobic compounds) for the food industry. Thus, the aim of this study will be establish a new method of extraction using I.L. for achievement of carotenoids from orange peel, which can be used as natural pigments in the food industry. Orange peel samples will be obtained in manufacturing industries of orange juice in São Paulo state, especially the residue that would be discarded, without any ranking or previous selection. Extractions of carotenoids from orange peel will be performed by conventional organic solvents and by ionic liquids. Four different I.L. will be tested as extractors, the 1-n-butyl-3-methylimidazolium tetrafluoroborate and the 1-n-hexyl-3-methylimidazolium chloride from trademark; and the 1-n-butyl-3-methylimidazolium chloride and the 1-n-butyl-3-methylimidazolium hexafluorophosphate synthesized in laboratory. The synthesis assay of the I.L. will be assisted by ultrasound, obtained without the use of harmful organic solvents, and the characterization of the I.L. will be performed by mass spectrometry (MS). Preliminary tests will be conducted for select the most effective I.L. for extraction of carotenoids from orange peel. The efficiency parameter assessed will be the yield in extraction of carotenoids (quantification by external calibration curve in HPLC-PDA). The two best I.L. will be selected to optimize the extraction using the response surface technique, through a fractional factorial design, followed by a full factorial design for the results of factors and levels that were significantly different (p<0.05). The qualitative and quantitative determination of carotenoids extracts will be performed by HPLC-PAD-MS/MS. The stability of carotenoids extracts obtained by conventional extraction and by I.L. will be assessed at different storage temperatures (50°C, 70°C and 100°C), and in two distinct systems: oily and watery. The antioxidant activity of carotenoids extracts will be evaluated by methods of deactivation of peroxyl radicals by lipophilic compounds in homogeneous system. Bioaccessibility and bioavailability assays will be performed, by in vitro digestion and uptake by Caco-2 cells of the carotenoids extracts. The analyzes will be performed in triplicate and the results will be statistically analyzed by ANOVA and Tukey test (p<0.05).