Preparation of Free, Soluble Conjugate, and Insoluble-Bound Phenolic Compounds from Peels of Rambutan (Nephelium lappaceum) and Evaluation of Antioxidant Activities in vitro
Version of Record online: 17 JAN 2012
© 2012 Institute of Food Technologists®
Journal of Food Science
Volume 77, Issue 2, pages C198–C204, February 2012
How to Cite
Sun, L., Zhang, H. and Zhuang, Y. (2012), Preparation of Free, Soluble Conjugate, and Insoluble-Bound Phenolic Compounds from Peels of Rambutan (Nephelium lappaceum) and Evaluation of Antioxidant Activities in vitro. Journal of Food Science, 77: C198–C204. doi: 10.1111/j.1750-3841.2011.02548.x
- Issue online: 17 FEB 2012
- Version of Record online: 17 JAN 2012
- MS 20110964 Submitted 8/7/2011, Accepted 11/7/2011.
- antioxidant activity;
- microwave-assisted extraction;
- phenolic compounds;
- response surface methodology
Abstract: The soluble phenolic compounds of rambutan peels (RP) were extracted by microwave-assisted extraction (MAE) and the operating parameters were optimized. The optimal conditions obtained were ethanol concentration of 80.85%, extraction time of 58.39 s, and the ratio of liquid to solid of 24.51:1. The soluble phenolic content by MAE was 213.76 mg GAE/g DW. The free, soluble conjugate, and insoluble-boaund phenolic compounds were prepared by alkaline hydrolysis, and the contents of 3 fractions were 185.12, 27.98 and 9.37 mg GAE/g DW, respectively. The contents of syringic acid and p-coumaric acid were high in the free fraction, showing 16.86 and 19.44 mg/g DW, and the soluble conjugate and insoluble-bound phenolics were mainly composed of gallic acid and caffeic acid. Furthermore, the antioxidant activities of 3 fractions were evaluated in 5 model systems. Results indicated that the free fraction had high antioxidant activities, compared with the soluble conjugate and insoluble-bound fractions.