Separation and quantitation of limonoids and flavonoids in juice and by-products of sweet orange (Citrus sinensis).

摘要

Two major classes of citrus phytochemicals, limonoids and flavonoids, have attracted considerable attention from science and industry because of their pharmacological properties. Large production of by-products accompanying orange juice production offers inexpensive starting materials for recovery of secondary metabolites with potential antic arcinogenic and cardioprotective activities.; The objectives of this study were (1) to determine limonoid and flavonoid content of orange juice and by-products resulting from commercial orange juice processing, and (2) to determine the influence of lime treatment on these phytochemicals.; Limonoid and flavonoid content was determined in various by-products (seed, peel, peel press cake, rag, and peel press liquid) and orange juice from commercially grown orange varieties (Hamlin, Parson Brown, and Valencia). Twenty-one compounds in the categories limonoid aglycones, limonoid glucosides, flavanone glucosides, and polymethoxylated flavones were analyzed.; Seeds had the highest content of limonoids, while peel and peel press cake had the highest concentrations of flavonoids. Water removal by pressing extracted limonoid glucosides and polymethoxylated flavones from the peel into peel press liquid, but concentrated limonin in peel press cake. Average g/100g dry wt. of total contents in solid fractions from three varieties were 7.1 (flavanone glucosides), 4.1 (limonoid glucosides), 1.2 (limonoid aglycones), and 0.26 (polymethoxylated flavones); and in liquid fractions were 0.150 (flavanone glucosides), 0.072 (limonoid glucosides), 0.009 (polymethoxylated flavones), and 0.002 (limonoid aglycones). Limonoid glucosides are rich in edible orange fraction and are extracted into the juice. The results show that rags containing seeds are good sources for limonoid aglycones and limonoid glucosides, while peels and peel press cake are good sources for flavanone glucosides and polymethoxylated flavones. Peel press liquid is a potential source for limonoid glucosides and polymethoxylated flavones after evaporation to the molasses end-product. Orange juice is a good source of limonoid glucosides.; In the lime study, limonoid and flavonoid content in waste products were measured before and after lime treatment. CaO was added to peel and rag, primary waste materials, so that the final concentration of CaO was 0.3% CaO (wet wt.).{09}After 48 hours, the samples were pressed to yield press cakes and press liquids. Seeds were treated with 0.3% CaO (wet wt.) separately. These fractions were analyzed for the content of limonoid aglycones, limonoid glucosides, flavanone glucosides and polymethoxylated flavones.; With lime treatment, more limonoid aglycones (25%) and limonoid glucosides (12%) leached from press cake into press liquid (rag and peel). Overall, there was a trend for increased phytochemical content release from press cakes into press liquids due to lime treatment. In seed, lime treatment resulted in losses of limonoid glucosides, but had no effect on limonoid aglycones, flavanone glucosides or polymethoxylated flavones. Lime treatment resulted in increased phytochemical content in press liquids especially limonoids.