Optimization of β-cyclodextrin-based extraction of antioxidant and anti-browning activities from thyme leaves by response surface methodology

Abstract

Thyme (Thymus vulgaris) has been demonstrated to extend the shelf-life of food products, being also a potential source of bioactive compounds. The aim of this research was to optimize the ultrasound assisted extraction employing β-cyclodextrin aqueous solutions as no-contaminant technology and Response Surface Methodology to obtain thyme extracts with the maximum antioxidant capacity. The optimal extraction conditions were: a solution of β-ciclodextrin 15 mM, an ultrasonic treatment time of 5.9 min at a temperature of 36.6 °C. They resulted in an extract with a polyphenolic content of 189.3 mg GAE/mL, an antioxidant activity (DPPH) of 14.8 mg GAE/mL, and ferric reducing/antioxidant power (FRAP) of 3.3 mg GAE/mL. Interestingly, the extract demonstrated to inhibit the production of Maillard browning products and can be considered a potential antiglycant agent. The obtained data is important for developing eco-friendly technologies in order to obtain natural antioxidant extracts with a potential inhibitory capacity of Maillard glycation reaction.

Keywords: 2,2-Diphenyl-1-picrylhydrazyl radical (DPPH) (PubChem CDI: 2735032); 2,4,6-Tripyridyl-s-triazine (TPTZ) (PubChem CID: 77258); Anti-glycation; Antioxidant activity; Bovine serum albumin (BSA) (PubChem CID: 16132389); Ferric chloride hexahydrate (PubChem CID: 6093258); Gallic acid (PubChem CID: 370); Glucose (PubChem CID: 5793); Maillard; Phosphate buffered saline (PBS) (PubChem CID: 24978514); Sodium carbonate trihydrate (PubChem CID: 10340); Thyme; Ultrasonic; β-Cyclodextrin; β-Cyclodextrin (β-CD) (PubChem CID: 444041).