Melanoidin Pigment Research Articles

Innovative process for improving functional and sensory quality of black garlic

Black garlic (BG) is an aged product high in brown melanoidin pigment and functional quality, however, the long aging process limits its commercial production. The present investigation was undertaken to develop an innovative process for improving the functional quality of BG as well as shortening the aging duration. Peeled garlic was subjected to two pre-treatment steps viz. Freeze-thaw (FT) and blanching (BL) followed by ascorbic acid (AA) infusion and effects were monitored during aging. Non-enzymatic browning, the main visible indicator of MR was significantly (p < 0.05) high in FT garlic due to high infused AA content. The pre-treated garlic showed significantly (p< 0.05) high fructose content (6-7-fold) over the control on the 6th day of aging. The treatment also enhanced the total phenolic content (2.5–3.0-fold) and antioxidant activity (14-fold) while reducing the processing time from 18 to 12 days. The soluble solid content (58.7 °B) and Fast index (fluorescent of advanced Maillard reaction products and soluble tryptophan) was maximum (305.2) in FT garlic on the 12th day. FTIR confirmed a strong peak at 1515 cm−1 depicting the dark nature of the BG subjected to FT. The innovative short process saved 50% of energy in production and was 43% more economical compared to its control counterpart. Overall sensory quality of FT garlic in terms of color, flavour and texture was on par with control except BL sample which showed high stickiness and low score values. Overall results suggest that FT treatment followed by infusion of ascorbic acid accelerated the Maillard reaction (MR), and improved the functional quality of BG.

Distillery Effluent Melanoidin Decolorization Induced by a Yeast Strain &lt;i&gt;Candida tropicalis&lt;/i&gt; (Y-2)

Molasses is used in the manufacturing of ethanol at sugarcane distilleries, which also produces a significant volume of effluent with melanoidin pigment and high BOD, COD, and pH. Melanoidin is a dark brown pigment that may be treated before disposal since it has a number of harmful consequences. This study’s objective was to identify possible melanoidin pigment-decolorizing yeast from natural resources and optimize it for various physiological, chemical, and dietary factors. From the various samples taken from the neighbouring distillery site, a total of 15 yeasts were isolated. Candida tropicalis (Y-2) was the name of the yeast strain that had the most colour decolorization. Within 32 hours of incubation, this strain of yeast displayed maximal decolorization (83%) at 35°C with 0.5% glucose, 0.5% peptone, 0.05% MgSO4, and 0.01% KH2PO4 pH-5. This yeast displayed maximal decolorization in the shortest amount of time while using the least quantity of carbon and nitrogen sources. This yeast strain may be used on an industrial scale to decolorize melanoidin since it is exceedingly successful. This is the first investigation of this unique strain of yeast that decolorizes spent wash.

Comparative adsorptive performance of adsorbents developed from sugar industrial wastes for the removal of melanoidin pigment from molasses distillery spent wash

Following the expansion of distillery industries, a large quantity of waste is being released to the environment containing high color-forming chemicals. This study aimed at degrading melanoidin pigment from distillery spent wash by using impregnated Sugarcane bagasse activated carbon (SCBAC) and Modified Bagasse Fly Ash (MBFA) as a comparative study. FTIR has revealed functional groups responsible for adsorption. A broad peak revealing an amorphous structure was observed for SCBAC while crystalline structure was observed in MBFA using XRD. SEM micrograph revealed an irregular macro-porous structure and regular structure for SCBAC and MBFA respectively. In the adsorption, important process parameters were optimized in response to color removal efficiency. At equilibrium, adsorption isotherm models, kinetics, mechanisms, and thermodynamics of the adsorption were studied. Langmuir model and Pseudo-second order result in the best fit for both adsorbents. Thermodynamics study revealed an exothermic process, feasibility, and spontaneity of the adsorption process for both adsorbents.

Mineralization of Melanoidin by H₂O₂ Producing Enzymes from Marine Cyanobacteria Oscillatoria boryana BDU 92181

Intracellular enzymes of Oscillatoria boryana BDU 92181 exhibited mineralizing activity on melanoidin, a recalcitrant pigment present in the distillery wastewater. Melanoidin decolourization was postulated to be due to the production of hydrogen peroxide and molecular oxygen released by the cyanobacterium during photosynthesis. The present study was aimed to find out the efficacy of the marine cyanobacterium O. boryana BDU 92181 in producing H2O2 and enzymes involved in hydrogen peroxide production with a view to utilize its potential for decolorization of melanoidin pigment in the distillery effluent. The enzymes involved in the melanoidin degradation have not so far been attempted with cyanobacteria.&#x0D; The results obtained in the present work suggested the activity of the glucose oxidase and Manganese peroxidase enzymes in a marine cyanobacterium Oscillatoria boryana BDU 92181 and whose activity was found to be enhanced in the presence of melanoidin.

Enhanced biodegradation of melanoidin pigment from spentwash using PDMS-immobilized microbes via ‘repeated addition’ strategy

Abstract Water resources such as rivers and oceans an indispensable resource for the living. The present investigation was carried out for biodegradation of industrial effluent by using bacterial isolates immobilized in PDMS sponges. Bacterial isolates DP4 Bacillus and DP7 Stenotrophomonas (black cotton soil of Maharashtra, India) was performed to degrade the industrial spentwash. In first experiment, effluent was added to the nutrient broth (NB) inoculated with DP4 and DP7 strains in different flasks containing PDMS sponges. DP4 strain degraded 84% of melanoidin as compared to DP7 strain, which degraded 50% melanoidin in 6 days. In second experiment, both bacterial strains were inoculated in (i) NB media (ii) immobilized in PDMS sponges, inoculated in NB media and the effluent was added. Degradation of melanoidin was determined at intervals of 24h using spectrophotometer (OD520nm). Immobilized cells degraded melanoidin better than free cells and Bacillus DP4 showed a higher degradation rate as compared to Stenotrophomonas DP7.

Parchment browning and the Dead Sea Scrolls – Part I: Artificial aging

The Dead Sea Scrolls, a two-thousand-year-old parchment corpus of manuscripts, thought to be the most important discovery of the 20th century including the first known copies of the Hebrew Bible, have darkened in parts to the point that the text is illegible. This motivated our research to try to understand the browning of parchment mechanisms. The scrolls cannot be analyzed by any destructive methods, so alternatives had to be sought. Here we describe a series of artificial aging experiments using modern parchment, prepared especially for our project, according to traditional methods, demonstrating how the different types of browning observed on the scrolls relate to environmental conditions as well as post finding treatments. Even the most extreme browning could be caused by prolonged exposure to water. This was in complete variance from controlled relative humidity exposure, where even elevated temperatures over a full five months caused only mild browning. We also confirm browning occurs at room temperature and within short periods when parchment is wet. We noted greater darkening of the flesh side in short term experiments, while browning was similar on both sides in conditions where water or humidity levels were maintained over a longer period. Artificial aging also confirmed the damage to the lower ends of many scrolls was likely caused by capillary actions when parchment was standing in water. That experiment also showed a dark tide-line phenomenon at the wet-dry interface, similar to that observed in paper substrates. Using analytical methods including FTIR, SEM, Light microscopy, UV–Vis and Fluorimetry we found the browning was always associated with denaturation, or loss of structure, mostly due to water and heat. This results in a flattening of the parchment structure which could be altering how light is reflected. However, in one artificial aging experiment the color was clearly seen to migrate and disperse over the parchment, after its initial formation. We believe this means the color is due to dark pigments; therefore, the main mechanism we suggest is melanoidin pigment formation due to a Maillard type reaction between amino acids and sugars or oxidized lipids, which are perhaps freed to react due to denaturation and hydrolysis. The results collected here can serve as an important step towards a full mechanistic understanding of parchment browning.

Degradation of anthocyanins and polymeric color formation during heat treatment of purple sweet potato extract at different pH

Purple sweet potato anthocyanins are common natural pigments widely used in food industry, while they are often thermally processed in application. Degradation of anthocyanins, formation of polymers and color changes of purple sweet potato extract (PSPE) were investigated at 90 °C in the range of pH 3.0–pH 7.0. Data analysis indicated a first-order reaction for anthocyanins degradation in solutions with pH 3.0, 5.0 and 7.0 have half-lives of 10.27, 12.42 and 4.66 h, respectively. The polymeric color formation followed zero-order kinetics, progressively increasing with pH values. The color of PSPE were changed with heating time and pH value through visual observation and colorimetric characterization. Analysis by UV–Vis spectrophotometry and HPLC indicated that anthocyanins in solution with pH 3.0 changed from monomeric anthocyanin into new polymers during heat treatment. Degradation of anthocyanins was accompanied by an increase in polymeric color index, due to the formation of melanoidin pigments and condensation reactions.

Local Molecular Reactivity of the Colored Dansylglycine in Water and Dioxane Studied through Conceptual DFT

This study evaluated a fixed long-range corrected range-separated hybrid (RSH) density functional associated with the Def2TZVP basis set alongside the SMD solvation model for the computation of the structure, molecular properties, and chemical reactivity of the M8 intermediate melanoidin pigment in the presence of water and dioxane. The preference of the active sites pertinent to radical, nucleophilic, and electrophilic attacks is made through linking them with the electrophilic and nucleophilic Parr functions, Fukui function indices, and condensed dual descriptor which are chemical reactivity descriptors that arise from conceptual density functional theory. The study confirmed the results from previous works showing that the MN12SX density functional is the most appropriate in predicting the chemical reactivity of this molecule in both solvents.

Blue M2: an intermediate melanoidin studied via conceptual DFT.

In this computational study, ten density functionals, viz. CAM-B3LYP, LC-ω PBE, M11, M11L, MN12L, MN12SX, N12, N12SX, ω B97X, and ω B97XD, related to the Def2TZVP basis sets, are assessed together with the SMD solvation model for calculation of the molecular properties and structure of blue-M2 intermediate melanoidin pigment. All the chemical reactivity descriptors for the system are calculated via conceptual density functional theory (DFT). The active sites suitable for nucleophilic, electrophilic, and radical attacks are selected by linking them with the Fukui function indices, electrophilic Parr functions, and condensed dual descriptors Δf(r), respectively. The prediction of the maximum absorption wavelength is considerably accurate relative to its experimental value. The study reveals that the MN12SX and N12SX density functionals are the most appropriate density functionals for predicting the chemical reactivity of the molecule under study.

Computational study of the chemical reactivity of the Blue-M1 intermediate melanoidin

Abstract This study assessed eight density functionals that include CAM-B3LYP, LC- ω PBE, M11, MN12SX, N12SX, ω B97, ω B97X, and ω B97XD related to the Def2TZVP basis sets together with the SMD solvation model. These are assessed in calculating the molecular properties and structure of the Blue-M1 intermediate melanoidin pigment. Notably, the chemical reactivity descriptors for the system are calculated via the Conceptual Density Functional Theory. The choice of active sites applicable to nucleophilic, electrophilic as well as radical attacks is made by linking them with Fukui functions indices, electrophilic Parr functions, and condensed dual descriptor Δ f ( r ) . The predicted maximum absorption wavelength tends to be considerably accurate relative to the experimental value. The study found the MN12SX and N12SX density functionals to be the most appropriate in predicting the chemical reactivity of the molecule under study.

Conceptual DFT Study of the Local Chemical Reactivity of the Colored BISARG Melanoidin and Its Protonated Derivative.

This computational study assessed eight fixed RSH (range-separated hybrid) density functionals that include CAM-B3LYP, LC-ωPBE, M11, MN12SX, N12SX, ωB97, ωB97X, and ωB97XD related to the Def2TZVP basis sets together with the SMD solvation model in the calculation the molecular structure and reactivity properties of the BISARG intermediate melanoidin pigment (5-(2-(E)-(Z)-5-[(2-furyl)methylidene]-3-(4-acetylamino-4-carboxybutyl)-2-imino-1,3-dihydroimidazol-4-ylideneamino(E)-4-[(2-furyl)methylidene]-5-oxo-1H-imidazol-1-yl)-2-acetylaminovaleric acid) and its protonated derivative, BISARG(p). The chemical reactivity descriptors for the systems were calculated via the Conceptual Density Functional Theory. The choice of active sites applicable to nucleophilic, electrophilic as well as radical attacks were made by linking them with Fukui functions indices, electrophilic and nucleophilic Parr functions, and the condensed Dual Descriptor Δf(r). The study found the MN12SX and N12SX density functionals to be the most appropriate in predicting the chemical reactivity of the molecular systems under study starting from the knowledge of the HOMO, LUMO, and HOMO-LUMO gap energies.

Conceptual DFT study of the local chemical reactivity of the dilysyldipyrrolones A and B intermediate melanoidins

This computational study assessed 11 density functionals related to Def2TZVP basis sets, namely CAM-B3LYP, LC- $$\omega $$ PBE, M11, M11L, MN12L, MN12SX, N12, N12SX, $$\omega $$ B97, $$\omega $$ B97X, and $$\omega $$ B97XD, and the SMD solvation model for calculating the molecular properties and structures of the intermediate melanoidin pigments, dilysyldipyrrolone A (XL-W1) and dilysyldipyrrolone B (XL-W2). The global and local chemical reactivity descriptors for the systems were calculated via conceptual density functional theory (DFT). The active sites applicable to nucleophilic, electrophilic, and radical attacks were chosen by connecting them with Fukui function indices, electrophilic Parr functions, and condensed dual descriptor $$\varDelta {f}({\mathbf {r}})$$ over the atomic sites. The predicted maximum absorption wavelength obtained directly from the HOMO–LUMO was more accurate relative to the experimental values of the MN12SX and N12SX density functionals than those obtained with TDDFT calculations. This study found the MN12SX and N12SX density functionals to be most appropriate for predicting the chemical reactivity of the molecules under study.

Molecular Reactivity and Absorption Properties of Melanoidin Blue-G1 through Conceptual DFT.

This computational study presents the assessment of eleven density functionals that include CAM-B3LYP, LC-wPBE, M11, M11L, MN12L, MN12SX, N12, N12SX, wB97, wB97X and wB97XD related to the Def2TZVP basis sets together with the Solvation Model Density (SMD) solvation model in calculating the molecular properties and structure of the Blue-G1 intermediate melanoidin pigment. The chemical reactivity descriptors for the system are calculated via the conceptual Density Functional Theory (DFT). The choice of the active sites related to the nucleophilic, electrophilic, as well as radical attacks is made by linking them with the Fukui function indices, the electrophilic Parr functions and the condensed dual descriptor f. The prediction of the maximum absorption wavelength tends to be considerably accurate relative to its experimental value. The study found the MN12SX and N12SX density functionals to be the most appropriate density functionals in predicting the chemical reactivity of the studied molecule.

Chemical Reactivity Theory (CRT) Study of the Melanoidin M8: Local Conceptual Density Functional Theory Descriptors

This study evaluated a fixed long-range corrected range-separated hybrid (RSH) density functional associated with the Def2TZVP basis set alongside the Solvation Model based on Density (SMD) for the computation of the structure, molecular properties and chemical reactivity of the M8 intermediate melanoidin pigment. The preference of the active sites pertinent to radical, nucleophilic and electrophilic attacks is made through linking them with the electrophilic and nucleophilic Parr functions, Fukui function indices, and condensed Dual Descriptor. This study showed that the MN12SX density functional is the most suitable one for predicting the chemical reactivity of this system.

Distillery spentwash decolorization by a noval consortium of Pediococcus acidilactici and Candida tropicalis under static condition.

The aim of this study was to isolate a consortium of bacterium and yeast from natural resources for better decolorization of distillery spentwash. Consortium exhibited 82±1.5% decolorization within 24 h when incubated at 45°C under static condition in effluent supplemented with 0.1%, glucose; 0.1%, peptone; 0.05%, MgSO4; 0.01%. The cultures were identified as Pediococcus acidilactici by 16S rDNA analysis and Candida tropicalis on the basis of phenotypic level. It is the first time when thermotolerant melanoidin decolorizing consortium (Pediococcus acidilactici and Candida tropicalis) isolated from distillery soil was capable to decolorizing melanoidin pigment of distillery effluent. Hence, it was observed that consortium has the ability to degrade the spentwash efficiently. This study could be an approach towards control of ecological pollution and health hazards of humans in and about the distillery location.

Photosynthetic assimilation of ¹⁴C into amino acids in potato (Solanum tuberosum) and asparagine in the tubers.

Asparagine is the predominant free amino acid in potato tubers and the present study aimed to establish whether it is imported from the leaves or synthesised in situ. Free amino acid concentrations are important quality determinants for potato tubers because they react with reducing sugars at high temperatures in the Maillard reaction. This reaction produces melanoidin pigments and a host of aroma and flavour volatiles, but if free asparagine participates in the final stages, it results in the production of acrylamide, an undesirable contaminant. 14CO2 was supplied to a leaf or leaves of potato plants (cv. Saturna) in the light and radioactivity incorporated into amino acids was determined in the leaves, stems, stolons and tubers. Radioactivity was found in free amino acids, including asparagine, in all tissues, but the amount incorporated in asparagine transported to the tubers and stolons was much less than that in glutamate, glutamine, serine and alanine. The study showed that free asparagine does not play an important role in the transport of nitrogen from leaf to tuber in potato, and that the high concentrations of free asparagine that accumulate in potato tubers arise from synthesis in situ. This indicates that genetic interventions to reduce free asparagine concentration in potato tubers will have to target asparagine metabolism in the tuber.

Decolorization of a recalcitrant organic compound (Melanoidin) by a novel thermotolerant yeast, Candida tropicalis RG-9

BackgroundSugarcane distilleries use molasses for ethanol production and generate large volume of effluent containing high biological oxygen demand (BOD) and chemical oxygen demand (COD) along with melanoidin pigment. Melanoidin is a recalcitrant compound that causes several toxic effects on living system, therefore, may be treated before disposal. The aim of this study was to isolate a potential thermotolerant melanoidin decolorizing yeast from natural resources, and optimized different physico-chemical and nutritional parameters.ResultsTotal 24 yeasts were isolated from the soil samples of near by distillery site, in which isolate Y-9 showed maximum decolorization and identified as Candida tropicalis by Microbial Type Culture Collection (MTCC) Chandigarh, India. The decolorization yield was expressed as the decrease in the absorbance at 475 nm against initial absorbance at the same wavelength. Uninoculated medium served as control. Yeast showed maximum decolorization (75%) at 45°C using 0.2%, glucose; 0.2%, peptone; 0.05%, MgSO4; 0.01%, KH2PO4; pH-5.5 within 24 h of incubation under static condition. Decolorizing ability of yeast was also confirmed by high performance liquid chromatography (HPLC) analysis.ConclusionThe yeast strain efficiently decolorized melanoidin pigment of distillery effluent at higher temperature than the other earlier reported strains of yeast, therefore, this strain could also be used at industrial level for melanoidin decolorization as it tolerated a wide range of temperature and pH with very small amount of carbon and nitrogen sources.

Physicochemical characteristics and antioxidant activity of melanoidin pigment from the fermented leaves of Orthosiphon stamineus

The melanoidin pigment (OS-M) was isolated from fermented leaves of Orthosiphon stamineus Benth. (Lamiaceae), with a 0.37% yield (from dry plant weight), and characterised. OS-M is a phenolic polymer with a molecular weight Keywords: of 4.4 kDa. Determination of basic physicochemical parameters using elemental antioxidant activity analysis, functional group analysis, UV-Vis-and FTIR-spectroscopy of OS-M fermented leaves indicated that the isolated polymer was similar to typical melanoidins. Experimental Lamiaceae data show that aromatic fragments dominate the OS-M structure, which also contains melanoidin a small amount of aliphatic fragments. Investigation into the antioxidant activity of Orthosiphon stamineus Benth OS-M under in vitro conditions demonstrated that O. stamineus melanoidin has a scavenging effect against free radicals (DPPH•, ABTS•+, O2•-) and NO molecules, inactivates molecules of H2O2, chelates Fe2+-ions and oxidises NADH.

Removal of melanoidin from molasses spent wash using fly ash-clay adsorbents

Removal of melanoidin pigment from molasses spent wash was investigated using a new adsorbent. Solid adsorbents were fabricated from charcoal fly ash and clay. The effect of various molasses concentration (6 to 12 g/l) on removal efficiency was studied. The obtained results revealed that maximum removal efficiency of 82% was achieved at the molasses concentration of 6 g/l and contact time of 7 h. The saturated porous adsorbents were regenerated and reused to conduct similar experiments. The achieved data showed that more than 90% of the capacity of the fresh adsorbent was recovered after regeneration. Various adsorption isotherms of Langmuir, Freundlich, Temkin and Harkins-Jura were applied to interpret the obtained experimental data. The obtained results revealed that the sorption data were well described by the Harkins-Jura model. Also, various kinetic models of pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion were used to predict the characteristic parameters which are useful in process design. It was concluded that the best fit was obtained with pseudo-second order kinetic model at low molasses concentrations.

Optimization of cultural conditions for anaerobically treated distillery effluent bioremediation by an isolate Pseudomonas putida SAG45

The present study deals with the decolourisation and detoxification of distillery effluent by an isolate SAG45. Soil samples were collected from the affected disposal sites of distillery effluent treatment plant. The isolate showed the highest bioremediation of 79.5% within 4 days of cultivation in the melanoidin pigment broth. The isolate showed higher decolourisation at pH 8.0 and temperature 37 oC. However, it gives 58.9% decolourisation with 5% (v/v) distillery effluent within 8 days. Toxicity test was also carried out to assess the toxicity of distillery effluent on seed germination.