Extraction, purification and antioxidant activity of polysaccharide from cold pressed oil cake of ‘Tengjiao’ seed

Abstract

Tengjiao (Zanthoxylum armatum DC.) seed cold pressed oil cake (CPC), the main by-product of the cold-pressed oil process, is mainly used for animal feed or crop fertilizer, resulting in a great waste of resources. To improve the added value, the CPC polysaccharide (CPCP) was extracted and purified, and its antioxidant activity was studied. The extraction conditions by microwave assisted extraction, and purification conditions by trichloroacetic acid and polyamide column chromatography treatment were optimized. High performance liquid chromatography and Fourier transforms infrared were applied to characterize the primary structural features. And the antioxidant activity was analyzed by detecting the reducing power, and scavenging activity on radical of superoxide anion, DPPH and ABTS. The results showed that, under the optimal extraction conditions (liquid-to-solid ratio 44 mL/g, processing time 16 min, microwave power 500 W and extraction temperature 80 °C), and the optimal purification conditions, the extract rate of crude CPCP reached 4.76 ± 0.07%, and the purity increased from 48.52 ± 2.76% to 93.76 ± 2.06%. CPCP was mainly water-soluble pyranose with α-configuration, and composed of five kinds of monosaccharides including L-Rhamnose, D-Glucuronic acid, d-Glucose, D-Galactose and D-(-)-Arabinose. CPCP displayed certain degree of antioxidant activity, revealing the potential development and utilization value as antioxidants.