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Journal of Food Quality
Volume 2017, Article ID 5232458, 10 pages
Research Article

Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L.) Seed at Subcritical Conditions with Statistical Analysis

School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang, Malaysia

Correspondence should be addressed to C. P. Leo; ym.msu@oelpchc

Received 7 July 2016; Revised 30 August 2016; Accepted 31 August 2016; Published 10 January 2017

Academic Editor: Amy Simonne

Copyright © 2017 N. I. Yusoff and C. P. Leo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Roselle seeds are the waste product of roselle processing, but they are now labeled as a polyphenol source with great herbal quality. In this work, polyphenols were extracted using ethanol-water (70% (v/v)) in a closed vessel under microwave irradiation. The main objective was to determine the optimal parameters statistically. The influence of extraction time (4–10 min), microwave power (100–300 W), and solvent/solid ratio (25–100 mL/g) was studied. The total phenolic and flavonoids content were determined using Folin-Ciocalteu and aluminum chloride methods, respectively. Without temperature control, the subcritical conditions could occur and the highest flavonoid content (14.4251 mg QE/g) was achieved at 158°C and 16.4 bar. Although the optimum MAE conditions (10 min, 300 W, and 97.7178 mL/g) resulted in the highest yield (65.0367%) and phenolic content (18.2244 mg GAE/g), low flavonoids content (6.4524 mg QE/g) was unexpectedly obtained due to degradation at 163°C.