76C-4 |
Influence of lime treatment on limonoid content in pressed cakes and pressed liquids of sweet oranges (Citrus sinensis) |
K. SUNTHANONT, M. A. Uebersax, and M. R. Bennink. Dept. of Food Science & Human Nutrition, Michigan State Univ., 204 G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824-1224 Limonoids, the highly oxygenated triterpenoids present in citrus fruits, have been shown to possess many health promoting functions such as anticarcinogenic and cardioprotective activities. Lime treatment is commonly used to facilitate drying of waste materials from juice processing before selling as low-cost cattle feed. An increased industrial trend in juice production, especially of oranges, reflects higher demands to utilize these lime treated by-products in more effective ways. Our objective was to obtain the distribution patterns of limonoids and their glucosides in pressed cakes and liquids of rag, peel and seeds of sweet oranges. Waste by-products from three orange cultivars (hamlin, parsonbrown, and valencia) including peels, rags, and seeds were treated with 0.3% CaO, then pressed before preparation for extraction. Both pressed solids and juices were investigated. The limonoids were divided into aglycones and glucosides and extracted separately due to the difference in solubility. Nonpolar compounds (aglycones) were held at 190°F for 1 hour and extracted by ethyl acetate at pH 2.5. Polar compounds (glucosides) were held at 190°F for 5 minutes before extracted by 70% methanol. The extracted compounds were analyzed by reverse phase HPLC at 210 nm [aglycones (seeds):ACN-MeOH-H2O (10:41:49), aglycone (rags and peels): 30% ACN to 80% in 3mM H3PO4 in 60 minutes, glucosides: 10% ACN to 26% in 3mM H3PO4 in 70 minutes]. Decrease in limonoid glucoside content was observed in pressed cakes and seeds, but increase in that was observed in pressed liquids. Limonin also followed the same trend as the glucosides. Nomilin and obacunone, the more nonpolar aglycones, were higher in lime-treat presscakes than in control. There was insignificant difference of limonoid aglycone content in press liquids. The results suggested that lime-treated by-products from orange juice processing could also be good sources for limonoids. The results also suggested selective sources for individual limonoids.
Session 76C, Citrus: General
|