Extraction, physicochemical properties, and antioxidant activity of natural melanin from Auricularia heimuer fermentation

Yinpeng Ma; Piqi Zhang; Xiaodong Dai; Xiuge Yao; Shuyang Zhou; Qingfang Ma; Jianing Liu; Shuang Tian; Jianan Zhu; Jiechi Zhang; Xianghui Kong; Yihong Bao

doi:10.3389/fnut.2023.1131542

Extraction, physicochemical properties, and antioxidant activity of natural melanin from Auricularia heimuer fermentation

Front Nutr. 2023 Feb 17:10:1131542. doi: 10.3389/fnut.2023.1131542. eCollection 2023.

Authors

Yinpeng Ma^{1

2}, Piqi Zhang², Xiaodong Dai², Xiuge Yao², Shuyang Zhou², Qingfang Ma², Jianing Liu², Shuang Tian², Jianan Zhu², Jiechi Zhang², Xianghui Kong², Yihong Bao¹

Affiliations

¹ College of Forestry, Northeast Forestry University, Harbin, China.
² Institute of Microbiology, Heilongjiang Academy of Sciences, Harbin, China.

Abstract

Introduction: Natural melanin from Auricularia heimuer have numerous beneficial biological properties, which were used as a safe and healthy colorant in several industries.

Methods: In this study, single-factor experiments, Box-Behnken design (BBD), and response surface methodology (RSM) were employed to investigate the effects of alkali-soluble pH, acid precipitation pH, and microwave time on the extraction yield of Auricularia heimuer melanin (AHM) from fermentation. Ultraviolet-visible spectrum (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and high-performance liquid chromatography (HPLC) were used to analyze the extracted AHM. The solubility, stability, and antioxidant activities of AHM were also measured.

Results: The results showed that alkali-soluble pH, acid precipitation pH, and microwave time significantly affected the AHM yield, with the following optimized microwave-assisted extraction conditions: alkali-soluble pH of 12.3, acid precipitation pH of 3.1, and microwave time of 53 min, resulting in an AHM extraction yield of 0.4042%. AHM exhibited a strong absorption at 210 nm, similar to melanin from other sources. FT-IR spectroscopy also revealed that AHM exhibited the three characteristic absorption peaks of natural melanin. The HPLC chromatogram profile of AHM showed a single symmetrical elution peak with a 2.435 min retention time. AHM was highly soluble in alkali solution, insoluble in distilled water and organic solvents, and demonstrated strong DPPH, OH, and ABTS free radical scavenging activities.

Discussion: This study provides technical support to optimize AHM extraction for use in the medical and food industries.

Keywords: Auricularia heimuer; HPLC; antioxidant activities; natural melanin; physicochemical properties.

Grants and funding

This work was financially supported by the Scientific Research Business Expenses of Heilongjiang Provincial Scientific Research Institutes (CZKYF2022-1-C019), the Scientific Research Foundation of Heilongjiang Academy of Sciences (KY2020SW01), and the Earmarked Fund for CARS 20 (Edible Mushroom).