Influences of Microwave-Assisted Extraction Parameters on Antioxidant Activity of the Extract from Akebia trifoliata Peels

Abstract

Akebia trifoliata is a fruit with rich nutritional properties, and its peel is produced as a by-product. In this research, we investigated the influences of microwave-assisted extraction parameters on antioxidant activity of the extract from Akebia trifoliata peels, and the ferric-reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) as well as total phenolic contents (TPC) were used to optimize extraction parameters. The influences of ethanol concentration, microwave power and solvent-to-material ratio, as well as extraction temperature and time on TPC, FRAP and TEAC values, were assessed using single-factor tests. Three parameters with obvious effects on antioxidant capacity were selected to further investigate their interactions by response surface methodology. The optimal extraction parameters of natural antioxidants from Akebia trifoliata peels were ethanol concentration, 49.61% (v/v); solvent-to-material ratio, 32.59:1 mL/g; extraction time, 39.31 min; microwave power, 500 W; and extraction temperature, 50 °C. Under optimal conditions, the FRAP, TEAC and TPC values of Akebia trifoliata peel extracts were 351.86 ± 9.47 µM Fe(II)/g dry weight (DW), 191.12 ± 3.53 µM Trolox/g DW and 32.67 ± 0.90 mg gallic acid equivalent (GAE)/g DW, respectively. Furthermore, the main bioactive compounds (chlorogenic acid, rutin and ellagic acid) in the extract were determined by high-performance liquid chromatography. The results are useful for the full utilization of the by-product from Akebia trifoliate fruit.

Phenolic Content, Main Flavonoids, and Antioxidant Capacity of Instant Sweet Tea (Lithocarpus litseifolius [Hance] Chun) Prepared with Different Raw Materials and Drying Methods

“…In another study, the yields of phloridzin and trilobatin were 34.76 ± 1.49 and 162.93 ± 1.73 mg/g, respectively [31], which were also close to our results. The FRAP, DPPH, and ABTS of MO and MY showed different trends among STFD and STSD; this could be explained by the fact that one or some compounds in extracts showed different responses for the FRAP, ABTS, and DPPH reagents, and this phenomenon has been similarly reported in previous studies [32,33].…”

Fermentation with Tea Residues Enhances Antioxidant Activities and Polyphenol Contents in Kombucha Beverages

“…The contents of phenolic compounds and caffeine in kombucha beverages were qualitatively and quantitatively determined by HPLC coupled with a photodiode array detector (PDA) (Waters, Milford, MA, USA) according to the literature [ 19 , 20 , 21 , 22 , 23 ]. An Agilent Zorbax Eclipse XDB-C18 column (4.6 × 250 mm, 5 µm, Santa Clara, CA, USA) was used for the separation.…”

Antioxidant Capacities and Polyphenol Contents of Kombucha Beverages Based on Vine Tea and Sweet Tea

“…The antioxidant activities were determined by ferric-reducing antioxidant power (FRAP) assay and Trolox equivalent antioxidant capacity (TEAC) assay, and the total phenolic contents (TPC) was determined by the Folin-Ciocalteu method. In addition, the concentrations of several bioactive components in two kombucha beverages were measured using high-performance liquid chromatography with photodiode array detector (HPLC-PDA) [ 12 , 17 ], including gallic acid, dihydromyricetin, myricetin, gallic acid, chlorogenic acid, catechin, rutin and ellagic acid. These kombucha beverages were studied for the first time, and found to possess strong high antioxidant activities (especially vine tea kombucha), which could be used as functional foods to prevent several diseases with related of oxidative stress.…”