Antioxidant Activity Of Melanoidins Research Articles

Structural characteristics, chemical compositions and antioxidant activity of melanoidins during the traditional brewing of Monascus vinegar

This study investigated the structural characteristics and chemical compositions of melanoidins in Monascus vinegar at different brewing stages through spectroscopic and HPLC-MS analysis. The results showed that melanoidins were exogenously added through the miwu rinsing process and not formed during fermentation. During aging, proteins and phenols continuously participated in melanoidin formation, increasing particle size, molecular weight, and antioxidant ability. FT-IR and 1H NMR spectra revealed that melanoidins mainly comprised carbohydrates, proteins, and phenols. The identified components included 10 carbohydrates (glucose being the main one), 18 amino acids, 8 free phenolics, and 15 bound phenolics (with ferulic acid as the major phenolic compound). Phenolic compounds, mainly bound through ester bonds, played a key role in improving the antioxidant activity of melanoidins. These findings provide a theoretical basis for regulating melanoidin formation during Monascus vinegar production.

Differences in structure, stability and antioxidant activity of melanoidins from lager and ale beers

Beer melanoidins, the final products of the Maillard reaction (MR), play a critical role in determining the flavor stability of beer due to their antioxidant properties. This study investigated the structure, stability, and antioxidant activity of lager beer melanoidins (LBM) and ale beer melanoidins (ABM). The results revealed that ABM possessed a higher browning index and molecular weight, attribute to its relatively intense MR. However, this intensity also led to a more unfolded and disordered structure in ABM. Conversely, LBM outperformed ABM in the FAST index, thermal stability, and total antioxidant activity because the low alcohol content in lager beer reduced oxidation and thermal degradation while boosting the stability and antioxidant activity of melanoidins. As a result, it would offer a novel possibility to improve beer flavor stability by optimizing the brewing process to modify the structural and functional characteristics of melanoidins.

Formation, Evolution, and Antioxidant Activity of Melanoidins in Black Garlic under Different Storage Conditions.

Melanoidins (MLDs) are formed through the reaction of carbonyl compounds and amino compounds in the Maillard reaction (MR) during the heating or storage of food. In this study, the formation, chemical composition, and structural characteristics of black garlic (BG) MLDs stored at different temperatures (4 °C, 20 °C, and 35 °C) over a period of 6 months were investigated. The initial products of the MR formed more often at 4 °C and 20 °C, while higher temperatures (35 °C) promoted the reaction in the middle and late stages of the MR. The higher temperature promoted an increase in molecular weight and MLD content, which can be attributed to the increase in protein and phenolic content. Elemental analysis confirmed an increase in nitrogen (N) content and the continuous incorporation of nitrogen-rich substances into the skeleton. Amino acids, particularly aspartic acid and threonine, were the primary N-containing compounds involved in MLD formation. Additionally, the infrared analysis revealed that the changes in MLDs during storage were characterized by amide I and amide II groups. The MR enhanced the yields of heterocyclic compounds (from 56.60% to 78.89%), especially that of O-heterocyclic compounds, at the higher temperature according to Py-GC-MS analysis. Furthermore, the higher temperature enhanced the molecular weight, maximum height, and roughness of MLDs compared to the control. The antioxidant ability of MLDs was positively correlated with storage temperatures. In summary, temperature had an impact on the formation, evolution, and antioxidant activity of MLDs.

Structural characterisation and antioxidant activity of melanoidins from high‐temperature fermented apple

SummaryHigh‐temperature fermented apple is a new fermented product with characteristic black appearance, which is prepared through natural fermentation of whole fresh apple at controlled high temperature (60–90 °C) and humidity (relative humidity of 50–90%). In this work, melanoidins from high‐temperature fermented apple were obtained by ultrafiltration and subsequent diafiltration. The structural characterisation of melanoidins was investigated in the present study. Results showed that the molecular weight of the obtained melanoidins was about 179 kDa and the melanoidins were comprised primarily of furans by pyrolysis–gas chromatography–mass spectrometry. Antioxidant activities of the high‐temperature fermented apple and its melanoidins were evaluated by ABTS, DPPH, hydroxyl radicals, ferric reducing antioxidant power and Fe2+‐chelating assays. Both high‐temperature fermented apple and its melanoidins showed extremely high antioxidant activities in scavenging hydroxyl radicals. High correlation between the antioxidant activity assayed methods and the physicochemical characteristics of melanoidins was obtained. The contribution of melanoidins to the total antioxidant capacity of high‐temperature fermented apple was determined.