School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China.
Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China.
Food Res Int. 2023 Feb;164:112045. doi: 10.1016/j.foodres.2022.112045. Epub 2022 Oct 19.
Melanoidins contribute to the sensory and functional properties of dark beers. The structure, stability, and antioxidant activity of acetone precipitation extracted melanoidins (APE-M) and macroporous resin adsorption extracted melanoidins (MAE-M) from dark beer were investigated. The structural properties of melanoidins were characterized using Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), scanning electron microscopy (SEM), and the solution storage stability, thermal behavior and antioxidant activity of melanoidins in dark beers were evaluated. MAE-M revealed more sophisticated structures than APE-M, including more concrete characteristics of Maillard reaction (MR) products in FTIR (1550-1500 cm), more ordered secondary structure in CD spectra, and thinner slices as well as more microspheres in SEM. The solution storage stability assay showed that certain factors, including 55 °C, 5 % v/v ethanol, UV light, and HO solution, accelerated the degradation of melanoidins. The moderate extraction process of MAE-M performed a minor enthalpy change (-92.28 Jg) in the DSC-TG test than that of APE-M (-319.41 Jg). Furthermore, the ABTS and DPPH radical scavenging activities and the FRAP assay demonstrated that the antioxidant activity of MAE-M was almost twice that of APE-M. In general, MAE was more effective in extracting beer melanoidins while maintaining its accurate structure and profitable antioxidant activity than APE.
类黑精赋予深色啤酒感官和功能特性。本研究分别采用丙酮沉淀法（APE）和大孔树脂吸附法（MAE）提取深色啤酒中的类黑精，分析其结构、稳定性和抗氧化活性。利用傅里叶变换红外光谱（FTIR）、圆二色光谱（CD）、扫描电子显微镜（SEM）等技术对类黑精的结构特性进行了表征，并对深色啤酒中类黑精的溶液稳定性、热行为和抗氧化活性进行了评价。与 APE-M 相比，MAE-M 具有更为复杂的结构，FTIR（1550-1500 cm-1）中具有更多的美拉德反应（MR）产物特征，CD 图谱中具有更有序的二级结构，SEM 中切片更薄且微球更多。溶液稳定性实验表明，55°C、5%v/v 乙醇、紫外光和 HO 溶液等因素会加速类黑精的降解。与 APE-M（-319.41 Jg）相比，MAE-M 的 DSC-TG 测试中温和的提取过程表现出较小的焓变（-92.28 Jg）。此外，ABTS 和 DPPH 自由基清除活性以及 FRAP 测定表明，MAE-M 的抗氧化活性几乎是 APE-M 的两倍。总体而言，与 APE 相比，MAE 更有效地提取啤酒类黑精，同时保持其准确的结构和有利的抗氧化活性。
