Effect of Maillard reaction on the formation of humic acid during thermophilic phase of aerobic fermentation

Mu, Daichen; Qu, Fengting; Zhu, Zechen; Wu, Di; Qi, Haishi; Mohamed, Taha Ahmed; Liu, Yumeng; Wei, Zimin

doi:10.1016/j.biortech.2022.127362

Cited by 18 publications

(6 citation statements)

References 24 publications

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“…These findings highlighted the involvement of certain intermediary compounds (e.g., amino acids and carbohydrates) in the depolymerization and oxidation processes, resulting in an increase in amidogen and hydroxyl groups bonded to aromatic rings [36]. This characteristic feature indicated the polyphenol-Maillard reaction, which encompassed the breakdown, reorganization, and bonding of proteins and sugars to form N-containing heterocycles [4].…”

Section: Discussionmentioning

confidence: 90%

“…This reaction can occur spontaneously when heat is applied without the involvement of microorganisms or biological enzymes. During this process, proteins and sugars undergo cleavage, rearrangement, and polymerization, resulting in the formation of N-containing heterocycles [4], which are characteristic of both HSs and HLSs. In the formation process of HSs or HLSs, biomacromolecules such as proteins, polysaccharides, lignins, and polyphenols are broken down into smaller molecules, including amino acids, sugars, and quinones.…”

Section: Introductionmentioning

confidence: 99%

“…The addition of exogenous precursors has been found to enhance the interconnection among various precursors and further facilitate the humification process [8]. Several studies have shown that the concentration of sugars has a substantial influence on the degree of humification [4]. Polysaccharides, as primary energy and C sources, are considered major contributors to the formation of HSs, particularly in the polyphenol-Maillard reaction, where they can facilitate the conversion of fulvic acid (FA) to humic acid (HA) [9].…”

Section: Introductionmentioning

confidence: 99%

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Changes in the Glucose Concentration Affect the Formation of Humic-like Substances in Polyphenol–Maillard Reactions Involving Gibbsite

Wang,

Cui,

Zhou

et al. 2024

Molecules

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The polyphenol–Maillard reaction is considered one of the important pathways in the formation of humic-like substances (HLSs). Glucose serves as a microbial energy source that drives the humification process. However, the effects of changes in glucose, particularly its concentration, on abiotic pathways remain unclear. Given that the polyphenol–Maillard reaction requires high precursor concentrations and elevated temperatures (which are not present in soil), gibbsite was used as a catalyst to overcome energetic barriers. Catechol and glycine were introduced in fixed concentrations into a phosphate-buffered solution containing gibbsite using the liquid shake-flask incubation method, while the concentration of glucose was controlled in a sterile incubation system. The supernatant fluid and HLS components were dynamically extracted over a period of 360 h for analysis, thus revealing the influence of different glucose concentrations on abiotic humification pathways. The results showed the following: (1) The addition of glucose led to a higher degree of aromatic condensation in the supernatant fluid. In contrast, the supernatant fluid without glucose (Glu0) and the control group without any Maillard precursor (CK control group) exhibited lower degrees of aromatic condensation. Although the total organic C (TOC) content in the supernatant fluid decreased in all treatments during the incubation period, the addition of Maillard precursors effectively mitigated the decreasing trend of TOC content. (2) While the C content of humic-like acid (CHLA) and the CHLA/CFLA ratio (the ratio of humic-like acid to fulvic-like acid) showed varying increases after incubation, the addition of Maillard precursors resulted in a more noticeable increase in CHLA content and the CHLA/CFLA ratio compared to the CK control group. This indicated that more FLA was converted into HLA, which exhibited a higher degree of condensation and humification, thus improving the quality of HLS. The addition of glycine and catechol without glucose or with a glucose concentration of 0.06 mol/L was particularly beneficial in enhancing the degree of HLA humification. Furthermore, the presence of glycine and catechol, as well as higher concentrations of glucose, promoted the production of N-containing compounds in HLA. (3) The presence of Maillard precursors enhanced the stretching vibration of the hydroxyl group (–OH) of HLA. After the polyphenol–Maillard reaction of glycine and catechol with glucose concentrations of 0, 0.03, 0.06, 0.12, or 0.24 mol/L, the aromatic C structure in HLA products increased, while the carboxyl group decreased. The presence of Maillard precursors facilitated the accumulation of polysaccharides in HLA with higher glucose concentrations, ultimately promoting the formation of Al–O bonds. However, the quantities of phenolic groups and phenols in HLA decreased to varying extents.

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Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Changes in the Glucose Concentration Affect the Formation of Humic-like Substances in Polyphenol–Maillard Reactions Involving Gibbsite

Wang,

Cui,

Zhou

et al. 2024

Molecules

View full text Add to dashboard Cite

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“…Among the different treatments, the addition of 0.12 mol/L glucose shows the most significant effect on improving the condensation degree of HLA molecules. The Maillard reaction involves the cleavage, rearrangement, and polymerization of proteins and sugars to form N-containing heterocycles, known as HLA [28]. Increasing the content of precursors can promote the Maillard reaction and improve the humification degree.…”

Section: Content Of Humic-like Acid (Chla) Chla/cfla Ratio and Ftir S...mentioning

confidence: 99%

Effect of Exogenous Glucose at Different Concentrations on the Formation of Dark-Brown Humic-like Substances in the Maillard Reaction Pathway Based on the Abiotic Condensation of Precursors Involving δ-MnO2

Wang

Zhang

et al. 2022

Sustainability

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The Maillard reaction is a type of nonenzymatic browning process and is an important pathway for the formation of humic-like substances (HLSs). Glucose is one of the three crucial precursors for the Maillard reaction, and a change in glucose concentration can inevitably affect the humification pathway, thereby regulating the composition and quality of HLSs. To verify the scientific hypothesis, the method of liquid shake-flask culture was adopted. Both catechol and glycine with fixed concentrations were added to a phosphate buffer including δ-MnO2, and only the concentration of glucose was adjusted in the sterile culture system. The obtained supernatant fluid and dark-brown residue were collected dynamically through the centrifugation method. The E4/E6 ratio and total organic C (TOC) of the supernatant fluid, the humus composition, and FTIR spectra for the dark-brown residue, and the elemental composition of humic-like acid (HLA) extracted from the dark-brown residue were analyzed to reveal the effect of varying glucose concentrations on the abiotic humification pathways for the Maillard reaction and the characteristics of relevant products under abiotic processes. The results reveal that (1) the exogenous addition of glucose at different concentrations simplifies the molecular structure in the supernatant fluid, and the TOC content is decreased to varying degrees, among which the addition of 0.24 mol/L glucose leads to the formation of simpler organic molecules in the supernatant compared to that for the other treatments, and the addition of 0.03 mol/L glucose shows the largest decrease in TOC content; (2) Under the coexistence of glycine and catechol, CHLA treated with the addition of glucose at different concentrations shows an upward trend in the course of the culture, which is significantly higher than that obtained for the CK control. The addition of 0.12 mol/L glucose results in the largest increase in CHLA. During the culture period, the structure of HLA molecules from each treatment first become complex and then gradually become simpler. Finally, the molecular structure of HLA treated with different concentrations of glucose becomes more complex, but the structure of HLA molecules from the CK control tends to be simplified. The addition of glucose can improve the condensation degree of HLA molecules, among which the addition of 0.12 mol/L glucose shows the most significant effect. With increasing exogenous glucose concentration, the number of N-containing compounds in the HLA molecules further decreases, while the number of O-containing functional groups increases. (3) The greater the concentration of glucose added, the higher the proportion of aromatic C structures in the dark-brown residue. During this process, the Mn-O bond lattice vibration of the δ-MnO2 layered structure is greatly enhanced. The organic molecules in the dark-brown residue and δ-MnO2 are bound to each other through intermolecular hydrogen bonding. The CHLA/CFLA ratio for each treatment increases to varying degrees after the culture period, indicating that the addition of glucose is more conducive to the improvement of humus quality than the CK control, among which the addition of 0.12 mol/L glucose shows the best effect.

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“…Most of these refractory substances belong to Maillard reaction products (MRPs) called melanoidins [19,20]. The Maillard reaction (MR) is a non-enzymatic browning reaction, which occurs between the carbonyl of reducing sugar and the amino group of the protein, amino acid, or peptide under heating conditions, including a series of sequential and parallel reaction pathways and depending strongly on the reaction conditions [21,22]. Melanoidins, as late-stage MRPs, are dark-colored macromolecular heterogeneous polymers, which mainly involve the structures of heterocyclic amines, furans, aldehydes, ketones, etc.…”

Section: Introductionmentioning

confidence: 99%

Review of Melanoidins as By-Product from Thermal Hydrolysis of Sludge: Properties, Hazards, and Removal

Li,

Zhang,

Xiao

et al. 2024

Processes

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Melanoidins, as macromolecular heterogeneous organic polymers, are produced from the Maillard reaction between amino and carbonyl groups during the thermal hydrolysis pretreatment (THP) of sludge. The brown color and recalcitrance of melanoidins pose a serious threat to wastewater treatment systems, such as invalidating UV disinfection and decreasing the efficiency of anaerobic digestion; thus, they have gradually received much concern in recent years. However, currently the study on THP-origin melanoidins is limited by a lack of reliable extraction and quantification methods. This paper presents a comprehensive review of the physical, chemical, and biological properties of melanoidins from different sources to fill the research gap on THP-origin melanoidins. The adverse effects of melanoidins on the management of wastewater and sludge are discussed, and for the first time, special attention is paid to the potential environmental hazards of THP-origin melanoidins to natural ecosystems. The removal technologies of melanoidins are summarized and compared as well. Finally, the suggested areas that future studies should focus on are provided. This review is dedicated to providing guidance on melanoidin research and management for the better development of the THP industry.

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Effect of Maillard reaction on the formation of humic acid during thermophilic phase of aerobic fermentation

Cited by 18 publications

References 24 publications

Changes in the Glucose Concentration Affect the Formation of Humic-like Substances in Polyphenol–Maillard Reactions Involving Gibbsite

Changes in the Glucose Concentration Affect the Formation of Humic-like Substances in Polyphenol–Maillard Reactions Involving Gibbsite

Effect of Exogenous Glucose at Different Concentrations on the Formation of Dark-Brown Humic-like Substances in the Maillard Reaction Pathway Based on the Abiotic Condensation of Precursors Involving δ-MnO2

Review of Melanoidins as By-Product from Thermal Hydrolysis of Sludge: Properties, Hazards, and Removal

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