Effect of high hydrostatic pressure conditions on the composition, morphology, rheology, thermal behavior, color, and stability of black garlic melanoidins

Melanoidins from stir-frying Atractylodes Macrocephala: Structural characterization, molecular weight distribution, and polyphenol delivery mechanism

This study investigates the chemical composition, structural characteristics, and functional properties of melanoidins from stir-frying Atractylodes Macrocephala. Formed through the Maillard reaction during thermal processing, melanoidins were fractionated into high molecular weight (MLD-2) and low molecular weight (MLD-1) components. The results demonstrated that MLD-2 exhibited greater browning intensity, enhanced antioxidant capacity, and improved polyphenol release in the colon, suggesting promising health benefits. Conversely, MLD-1 demonstrated higher fluorescence intensity and distinct thermal characteristics. Structural analysis using FT-IR, NMR, UV-vis, and fluorescence spectroscopy confirmed that molecular weight plays a crucial role in determining the functional properties of melanoidins. These findings underscore the potential of melanoidins as effective carriers for polyphenol delivery, providing valuable insights into their role in enhancing the bioavailability and therapeutic effects of bioactive compounds, particularly in the context of traditional herbal medicines.

Rheological effects of high-pressure processing and high-pressure homogenization on not-from-concentrate orange juice

BACKGROUND

'Not-from-concentrate' (NFC) orange juice faces stability challenges. Its rheological properties are also important for optimizing processes such as pumping. These issues affect companies in terms of their cost implications, and they affect product quality and consumer acceptance directly. This study investigates the rheological properties of NFC orange juice subjected to high-pressure homogenization (HPH) following high-pressure processing (HPP).

RESULTS

The viscosity coefficient (k) of HPH-treated orange juice reduced significantly, by 92.16%, and was accompanied by a 163.82% increase in the flow coefficient (n) and a 48.12% increase in zeta potential. High-pressure processing treatment reduced viscosity effectively while enhancing the fluidity and stability of the orange juice. However, no significant differences were observed in the major functional groups or particle size distribution in comparison with a thermal pasteurization (TP) group. Alterations in the polysaccharide structure were identified as the primary reason for the observed changes in rheological properties. Specifically, the molecular weight (Mw) of soluble dietary fiber (SDF) increased, whereas the Mw of cellulose decreased in the HPP treated juice. This correlated with the results for viscosity, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) analyses.

CONCLUSION

In comparison with the TP group, the fluidity, and stability of HPH orange juice after HPP were enhanced significantly, and the viscosity was reduced. This speeds up the juice-pumping process, reducing energy consumption and costs. The combination of HPP and HPH pretreatment effectively improved the physical properties and sensory quality of orange juice. © 2025 Society of Chemical Industry.

Unraveling the mysteries of melanoidins: insights into formation, structure, and health potential in fermented blacken foods

Fermentation is widely known for its ability to enhance the food nutritional ingredients, and its products are with improved texture, flavor, and nutritional. Fermented blacken foods (FBF) are a unique group of foods characterized by their darker hue while retaining nutritional benefits. Despite their popularity, research on melanoidins, the compounds responsible for the characteristic color and health-promoting properties of FBF, remains limited. This review summarizes the formation, extraction, purification, structural features, and health benefits of melanoidins in FBF. The relationship between preparation methods, and physicochemical properties and bioactivities was elucidated. The formation of melanoidins in FBF, influenced by the Maillard reaction (MR) and microbial metabolic activity is analyzed, highlighting the dynamic nature of melanoidin synthesis in fermentation systems. Furthermore, the review addresses the characteristics of FBF production processes and the role of microorganisms and enzymes in melanoidin formation. Melanoidins in FBF exhibit diverse chemical compositions and molecular structures, influenced by precursor molecules, reaction pathways, and environmental factors. These compounds contribute to the sensory attributes, stability, and bioactivity of FBF including antioxidant, antimicrobial, and prebiotic properties. This review underscores the importance of melanoidins in FBF and their influences on food quality, nutrition, and health.

Comparison of characterization and composition of melanoidins from three different dried apple slices

The composition of melanoidins in dried apple that affects quality remains unclear. The composition and structure of melanoidins in dried apple slices by hot air drying (HAAM), instant controlled pressure drop drying (DICAM), and vacuum freeze-drying (FDAM) were investigated. It showed that the melanoidins were highly heterogeneous mixtures with a light-yellow color and blue-green fluorescence, belonging to polysaccharide-type melanoidins. Specifically, HAAM had a large molecular weight (929.5 g/mol) and wide molecular weight distribution, with more double-bond conjugated systems. DICAM (610.9 g/mol), possessing the strongest fluorescence intensity, was mainly composed of compounds with fewer π-conjugated structures and more electron-donating groups. As a control, the low level of Maillard reaction in FDAM resulted in the formation of the smallest molecular weight (458.6 g/mol) with weak fluorescence intensity. Moreover, 10 compounds were tentatively identified in apple melanoidins. This study provides the foundation for the future functional preparation of apple melanoidins.

Ultra-high pressure treatment improve the content of characteristic aromatic components of melon juice from the view of physical changes

Introduction

The effectiveness of ultra-high pressure (UHP) technology in retaining the flavor of fresh fruit and vegetable juices has been acknowledged in recent years. Along with previously hypothesized conclusions, the improvement in melon juice flavor may be linked to the reduction of its surface tension through UHP.

Methods

In this paper, the particle size, free-water percentage, and related thermodynamic parameters of melon juice were evaluated in a physical point for a deeper insight.

Results

The results showed that the UHP treatment of P2-2 (200 MPa for 20 min) raised the free water percentage by 7,000 times than the other treatments and both the melting enthalpy, binding constant and Gibbs free energy of P2-2 were minimized. This significantly increased the volatility of characteristic aromatic compounds in melon juice, resulting in a 1.2-5 times increase in the content of aromatic compounds in the gas phase of the P2-2 group compared to fresh melon juice.

Plant polysaccharides extracted by high pressure: A review on yields, physicochemical, structure properties, and bioactivities

Polysaccharides are biologically essential macromolecules, widely exist in plants, which are used in food, medicine, bioactives' encapsulation, targeted delivery and other fields. Suitable extraction technology can not only improve the yield, but also regulate the physicochemical, improve the functional property, and is the basis for the research and application of polysaccharide. High pressure (HP) extraction (HPE) induces the breakage of raw material cells and tissues through rapid changes in pressure, increases extraction yield, reduces extraction time, and modifies structure of polysaccharides. However, thus far, literature review on the mechanism of extraction, improved yield and modified structure of HPE polysaccharide is lacking. Therefore, the present work reviews the mechanism of HPE polysaccharide, increasing extraction yield, regulating physicochemical and functional properties, modifying structure and improving activity. This review contributes to a full understanding of the HPE or development of polysaccharide production and modification methods and promotes the application of HP technology in polysaccharide production.

Nanosized quantum dots-wrapped metallic particles ensembles integrated into filter disc-based analytical device for garlic evaluation. Application to monitor fake pickled garlic in balsamic vinegar

Herein, an affordable and simple analytical device is presented to portable identify of garlic in 30 min; the evaluation needs no pre-treatment of sample. The analytical device fabrication was did employing a headspace-based nanosensor array using of inexpensive materials as commercial filter discs, quantum dots (QDs), and metallic nanoparticles (MNPs). The nanoarray is fabricated by the accumulation QDs on MNPs surface, that results in the production of ensembles of QDs/MNPs. The ensembles generate diverse colorimetric profiles as "fingerprints" regarding to each garlic sample. The volatile organosulfur compounds (OSCs) of garlic can prefer binding to the MNPs comparing with QDs. The color profiles can be displayed with a smartphone camera, which can be quantitatively distinguished by chemometrics approaches. The analytical device was used to assessment of fake pickled samples in balsamic vinegar. This device proves well potential for qualitative control of garlic.

Anti-Cancer and Anti-Inflammatory Properties of Black Garlic

Black garlic (BG) is a fermented form of garlic (Allium sativum L.), produced at precisely defined temperatures, humidities, and time periods. Although garlic has been used for thousands of years, black garlic is a relatively new discovery. There are many bioactive compounds in black garlic that give it medicinal properties, including anti-inflammatory and anti-cancer properties. In our review article, we present scientific studies examining the anti-inflammatory and anti-cancer effects of black garlic. According to research, this effect is mainly due to the reduction in the production of pro-inflammatory cytokines, as well as the ability to scavenge free oxygen radicals and induce apoptosis. In addition, the phytochemicals contained in it have antiproliferative and antiangiogenic properties and inhibit the growth of cancer cells. Black garlic is a valuable source of biologically active substances that can support anti-inflammatory and anti-cancer therapy. Compared to Allium sativum, black garlic has fewer side effects and is easier to consume.

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.

Method development for the identification, extraction and characterization of melanoidins in thermal hydrolyzed sludge

Melanoidins, the brown late-stage Maillard reaction products, are responsible for color development and refractoriness in thermal hydrolyzed sludge (THS), causing negative effects on wastewater treatment. This study aimed to develop a methodology for the identification, isolation and preliminary characterization of the THS melanoidins. After thermal hydrolysis, the formation of melanoidins were confirmed by physicochemical indicators and excitation-emission matrix fluorescence analysis. The macroporous resin adsorption method was adopted to successfully extract melanoidins from THS with high recovery and selectivity. The main chemical components of the extracted melanoidins were carbohydrate (23.1 %), protein (43.8 %) and phenol (13.7 %), and the C/N was 4.5. In addition, furans, alcohols and sulfur-containing volatile substances were detected by pyrolysis-gas chromatography-mass spectrometry. Fourier transform infrared spectroscopy determined that functional groups such as CO, CN, NH, C-O-C, amide I and phenyl were present in the structure of THS melanoidins, and nuclear magnetic resonance spectroscopy indicated the formation of heterocyclic macromolecular structures. Their formation pathways were speculated to involve the cross-linkage of low-molecular-weight components (e.g. proteins, Amadori and Schiff base compounds) and the polymerization of heterocyclic units (e.g. furans, pyroles and pyrazines). The above results clarify the fundamental characteristics of the melanoidins formed during sludge thermal hydrolysis and will help improve subsequent research on melanoidins control.

Structure, chemical stability and antioxidant activity of melanoidins extracted from dark beer by acetone precipitation and macroporous resin adsorption

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-1), 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 H2O2 solution, accelerated the degradation of melanoidins. The moderate extraction process of MAE-M performed a minor enthalpy change (-92.28 Jg-1) in the DSC-TG test than that of APE-M (-319.41 Jg-1). 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.

Cold plasma: a promising technology for improving the rheological characteristics of food

At the beginning of the 21st century, many consumers show interest in purchasing safe, healthy, and nutritious foods. The intent requirement of end-users and many food product manufacturers are trying to feature a new processing technique for the healthy food supply. The non-thermal nature of cold plasma treatment is one of the leading breakthrough technologies for several food processing applications. The beneficial response of cold plasma processing on food quality characteristics is widely accepted as a substitution technique for new food manufacturing practices. This review aims to elaborate and offer crispy innovative ideas on cold plasma application in various food processing channels. It highlights the scientific approaches on the principle of generation and mechanism of cold plasma treatment on rheological properties of foods. It provides an overview of the behavior of cold plasma in terms of viscosity, crystallization, gelatinization, shear stress, and shear rate. Research reports highlighted that the cold plasma treated samples demonstrated a pseudoplastic behavior. The published literatures indicated that the cold plasma is a potential technology for modification of native starch to obtain desirable rheological properties. The adaptability and environmentally friendly nature of non-thermal cold plasma processing provide exclusive advantages compared to the traditional processing technique.

Exploring polymerisation of methylglyoxal with NH3 or alanine to analyse the formation of typical polymers in melanoidins

To investigate the formation of typical melanoidin polymers, methylglyoxal (MGO) with NH₃ or alanine (Ala) was used to form coloured compounds, with glyoxal or acetone used as controls. The products were characterised using chromatography, mass spectrometry, and spectroscopy. Spectroscopic results showed that the coloured compounds formed were similar to melanoidins in food. GC-MS results showed that the MGO-based reaction generated similar volatile compounds using the Maillard reaction. Mass spectrometry showed that the molecular weights of structural units in the polymers were mainly 162, 169, and 176 Da, and these could be reassembled using the basic units derived from MGO alone or in combination with nitrogen. Hence, polymers recombined using basic structural units should be considered while determining melanoidin biomarkers. The preparation of coloured compounds using MGO with NH₃ can be used as a novel method to produce the control compounds for melanoidin after process optimization.

Dissecting dietary melanoidins: formation mechanisms, gut interactions and functional properties

Dietary melanoidins are late stage Maillard reaction products (MRPs), browning colorants and predominantly high molecular weight (HMW) chemicals. They originate through polycondensation reactions of reducing sugars and proteins or amino acids upon thermal processing. Their presence in several daily food and beverages (i.e. coffee, beer, honey, bakery products, chocolate, grilled meat) contribute to food sensory characters (i.e. color, aroma, and flavor). Additionally, melanoidins exhibit many biological attributes (i.e. antioxidant, anti-obesity, antibacterial activity and impact on gut microbiota as prebiotics). However, dissecting melanoidins specific biological and functional characteristics in relation to their metabolism and gut interaction with link to their chemical structures has yet to be reported in literature. For a better understanding of melanoidins benefits and flavor properties in processed foods, this review represents a state of the art comprehensive insight of its formation mechanism and chemistry in relation to their functionalities and health effects. Further, a compile of the factors affecting melanoidins production to optimize for the best flavor attributes while minimizing hazardous compounds is presented. This study presents the first analysis of melanoidins gut interaction in context to its different action mechanisms.

Effects of Anaerobic Fermentation on Black Garlic Extract by Lactobacillus: Changes in Flavor and Functional Components

The purpose of this study is to investigate the potential application of probiotics in the development of novel functional foods based on black garlic. The single-factor analysis (extraction temperatures, solid-to-liquid ratios, and extraction times) and the response surface methodology were firstly used to optimize hot water extraction of soluble solids from black garlic. The optimal extraction conditions were temperature 99.96°C, solid-to-liquid ratio 1:4.38 g/ml, and extracting 2.72 h. The effects of Lactobacillus (Lactobacillus plantarum, Lactobacillus rhamnosus, and co-culture of them) fermentation on the physicochemical properties of black garlic extract broth were studied for the first time. Artificial and electronic sensory evaluations demonstrated that fermentation significantly influenced the sensory characteristics. The variations of metabolites in different broth samples (S1, unfermented; S2, 1-day fermentation by L. plantarum; S3, 2-day fermentation by L. rhamnosus; and S4, 1-day fermentation by co-cultured Lactobacillus) were further investigated by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry/mass spectrometry analysis. As a result, Lactobacillus fermentation significantly reduced the pH; increased the contents of the total acid, amino nitrogen, total polyphenol, and total flavonoid; and reduced the content of 5-hydroxymethylfurfural (a carcinogenic component) by 25.10-40.81% in the black garlic extract. The contents of several components with unpleasant baking flavors (e.g., furfural, 2-acetylfuran, and 5-methyl furfural) were reduced, whereas the contents of components with green grass, floral, and fruit aromas were increased. More importantly, the contents of several functional components including lactic acid, Gly-Pro-Glu, sorbose, and α-CEHC (3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-propanoic acid) were increased after Lactobacillus fermentation. The results demonstrated the potential of probiotic fermentation to improve the quality of black garlic. This work will provide an insight into the strategic design of novel black garlic products and facilitate the application of black garlic in functional foods.

Formation mechanisms and characterisation of the typical polymers in melanoidins from vinegar, coffee and model experiments

Melanoidins, are of increasing interest for their potential biological activities. However, little knowledge is available on their structure. In the present study, vinegar, coffee and model melanoidins were degraded by NaBH₄, and the resultant reaction products were characterised by chromatography, mass spectrometry and spectrometry methods to elucidate the mechanism of formation of melanoidin skeleton molecules. The study identified a typical polymer with a molecular weight (MW) interval of 74 Da, which was polymerised by aldol condensation and reduced by NaBH₄, followed by intermolecular dehydration. MW of the theoretically derived typical polymers matched the detected polymers, validating the speculated pathway involved in the formation of melanoidins skeleton molecules. The study also revealed that melanoidins from different sources contain polymers with the same MW and different binding preferences, contributing to the heterogeneity of melanoidins. Overall, these findings indicated that the identified polymers could be used as potential candidate biomarkers for melanoidins.