Thesis Archive
MICROWAVE ASSISTED EXTRACTION OF PHENOLIC COMPOUNDS FROM UBE (Dioscorea alata L.) PEELS
Deniel Manuel L. de los Reyes
Jessica J. Koa Lee
Sarah Katrina K. Te
Abstract:
The study conducted was the optimization of the microwave assisted extraction of phenolic compounds from ube (Dioscorea alata L.) peels. Based on different studies, ube peels contain phenolic compounds that are beneficial for the human health and these peels are already treated as waste once the ube meat is obtained; thus, it was chosen as the sample for this study.
The extraction of phenolic compounds from the ube peels were done using microwave assisted extraction. It was done using three different parameters at three different levels: microwave power (140, 420 and 700 watts) which is microwave energy delivered into the ube peels, extraction time (2, 5 and 8 minutes) and solid-to-solvent ratio (1:40, 1:60, 1:80 mg/mL). The solvent used throughout the experiment was fixed at 60% (v/v) ethanol. The yield of total phenolic compounds and yield of total anthocyanin content were determined using the Folin Ciocalteau method and HPLC analysis, respectively. The responses for the total phenolic compounds yield were expressed in terms of gallic acid equivalent (GAE) in three ways: yield of total phenolic compounds (mg GAE/ 100 g), yield of total phenolic compounds per power (mg GAE/ 100 g – W) and yield of total phenolic compounds per time (mg GAE/ 100 g – min.).
Out of the three responses, the yield of total phenolic compounds per power gave the highest yield at 578.51 mg GAE/ 100 g of peels. The optimum conditions, determined using the RSM model, of the microwave power, extraction time and solid-to-solvent ratio were found to be at 140 watts, 2 minutes and 1:66.49 mg/mL, respectively. A verification run was done and compared to the model, which had an error of 2.06%. For the determination of the total anthocyanin content, which was expressed in terms of cyanidin-3-O-glucoside (C3G), the highest, median and lowest for each response from the total phenolic compounds yield were tested. The results showed that the highest total phenolic compounds yield had the highest total anthocyanin content with 170.32 mg C3G/ 100 dry ube peel sample.
Adviser:
Dr. Cynthia F. Madrazo
Dr. Luis Razon