Optimizing Pulsed Ultrasound-Assisted Extraction of Antioxidants from Linden and Quantification by HPLC-PDA


AKYÜZ E.

FOOD ANALYTICAL METHODS, 2022 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2022
  • Doi Number: 10.1007/s12161-022-02388-y
  • Journal Name: FOOD ANALYTICAL METHODS
  • Journal Indexes: Science Citation Index Expanded, Scopus, Agricultural & Environmental Science Database, CAB Abstracts, Compendex, Food Science & Technology Abstracts, INSPEC, Veterinary Science Database
  • Keywords: Extraction techniques, Ultrasonic, HPLC-PDA, Antioxidant capacity, Linden, Polyphenols, PHENOLIC COMPOSITION, WATER EXTRACTION, CAPACITY, L., POLYPHENOLS, OPTIMIZATION, TEAS, EFFICIENCY, INFUSION

Abstract

The scope of the study is optimizing pulsed ultrasound-assisted extraction conditions by evaluating linden's antioxidant capacity as mu mol Trolox equivalent per g by using CUPRAC assay and correlating the total antioxidant capacity with high-performance liquid chromatography (HPLC) results. Solvent type, solvent ratio, solid-to-liquid ratio, sonication time, sonication clearance time, and extraction time were studied as extraction parameters. Particularly pulse durations as sonication "on" and "off" time have been firstly investigated in this study. The optimal parameters were as follows: 0.5 g 20 mL(-1), 60% methanol, 2 s on/2 s off sonication, and 40-min extraction time. Different extraction methods such as pulsed ultrasound-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction using a water bath, and infusion-assisted extraction were compared by applying the CUPRAC, ABTS, and DPPH assays for total antioxidant capacity and Folin assay for total phenolic content. The most effective extraction technique was found as pulsed ultrasound-assisted extraction according to the results of the spectrophotometric assays. The individual polyphenolic components of linden extract were determined and quantified by HPLC on a C18 column using a gradient elution of mobile phase including 3% acetic acid (A)-methanol (B) performed with photodiode array detection at 270 nm and 1 mL min(-1) flow rate. Fifteen polyphenolics were identified in linden extract by using HPLC-PDA analyses. It will provide the determination of individual polyphenols at a single chromatographic run as well as the evaluation of the contribution of polyphenols to spectrophotometric TAC values of linden extract with the combined HPLC-CUPRAC method.