Novel eco-friendly extraction of high purity Eucommia ulmoides gum via composite enzyme hydrolysis pretreatment combined with a PEG-4000 aqueous solvent biphasic system

Abstract

Utilizing Eucommia ulmoides pericarp samaras as the raw material, a novel strategy for extracting Eucommia ulmoides gum (EUG) through composite enzyme hydrolysis pretreatment combined with a biphasic solution system consisting of PEG-4000 aqueous solution and petroleum ether was established for the first time. Optimal complex enzymatic hydrolysis parameters were as follows: hydrolysis time was 13 h, liquid–solid ratio was 12 : 1 mL g⁻¹ and composite enzyme dosage was 1.1%. The maximum purity and maximum yield of refined EUG (EUG-3) were 98.25% and 15.77%, respectively. The physicochemical structure, microstructure, molecular weight and crystal structure of EUG-1 (commercially available EUG), EUG-2 (petroleum ether extraction EUG) and EUG-3 were characterized by attenuated total reflection infrared (ATR-IR) spectroscopy, hydrogen nuclear magnetic resonance (¹H NMR) spectroscopy, field emission scanning electron microscopy (SEM), gel permeation chromatography (GPC) and X-ray diffraction (XRD), respectively. Differential scanning calorimetry (DSC) results indicated that the melting point and glass transition temperature of extracted EUG-3 were stable. EUG-3 displayed better mechanical properties, compared with EUG-1 and EUG-2. The high-purity EUG extracted using this method is expected to be developed into multifunctional biomedical materials with excellent application prospects.