Chitosan-glucose derivative membrane obtained by Maillard reaction improves cartilage repair in a rabbit model.

BACKGROUND: Treatment of articular cartilage injury remains a challenging clinical problem in orthopedics. Chitosan-derived biomaterial could be a potential adjuvant treatment to improve cartilage repair. In the current study, we examined the effects of two potential chitosan-derived materials on cartilage regeneration of osteochondral defects in rabbits. METHODS: An osteochondral defect was created over the rabbit knee and treated using three approaches: group A received no material (n = 24), group B received chitosan membranes with glucose absorption (CGA; n = 25), and group C received chitosan-glucose derivative membranes obtained via the Maillard reaction (CGMR; n = 25). Cartilage repair over the osteochondral defect was analyzed 12 weeks post-surgery via histological analysis, immunostaining, and reverse transcription-qualitative polymerase chain reaction (RT-qPCR) for type-I and type-II collagen mRNA. RESULTS: According to histological analysis, CGMR-treated defects showed significantly improved modified O'Driscoll scoring when compared with no material- and CGA-treated defects (20.9 ± 4.3 vs. 13.00 ± 2.5 and 17.7 ± 4.6, p < 0.001). Moreover, group C exhibited higher intensity of type-II collagen immunohistochemical staining over the regenerated cartilage than groups A and B, along with increased expression of type-II collagen mRNA by RT-qPCR. CONCLUSIONS: CGMR might improve cartilage regeneration in osteochondral defects.

Why does distilled liquor (Baijiu) have a yellowish color: A comprehensive analysis.

Elucidating the mechanisms underlying Baijiu production is a shared aspiration among academic groups specializing in the field of Baijiu research. This study comprehensively examined the mechanisms underlying the yellowish coloration of Baijiu through a synergistic application of chromatographic, spectroscopic, and physical methodologies. Aging of Baijiu in earthenware pots involves the infiltration of mineral ions such as iron, aluminum, and calcium; however, these ions are detected at extremely low concentrations and are therefore not linked to the development of Baijiu's yellowish color. Instead, the yellowish coloration is attributed to the diverse colorants generated during the high-temperature fermentation of small-molecule sugars derived from the saccharification of grain materials. Although these colorants exist in minimal quantities and exhibit spectral absorption peaks ranging from 300 to 450 nm, their overlapping spectra collectively contribute to the light-absorbing properties of Baijiu across a broad wavelength range, ultimately accounting for its characteristic yellowish color.

Versatile Keratin Fibrous Adsorbents with Rapid-Response Shape-Memory Features for Sustainable Water Remediation.

Biodegradable shape-memory polymers derived from protein substrates are attractive alternatives with strong potential for valorization, although their reconstruction remains a challenge due to the poor processability and inherent instability. Herein, based on Maillard reaction and immobilization, a feather keratin fibrous adsorbent featuring dual-response shape-memory is fabricated by co-spinning with pullulan, heating, and air-assisted spraying ZIF-8-NH2. Maillard reaction between the amino group of keratin and the carbonyl group of pullulan improves the mechanics and thermal performance of the adsorbent. ZIF-8-NH2 immobilization endows the adsorbent with outstanding multipollutant removal efficiency (over 90%), water stability, and photocatalytic degradation and sterilization performance. Furthermore, the adsorbent can be folded to 1/12 of its original size to save space for transportation and allow for rapid on-demand unfolding (12 s) upon exposure to water and ultraviolet irradiation to facilitate the adsorption and photocatalytic activity with a larger water contact area. This research provides new insight for further applications of keratin-based materials with rapid shape-memory features.

The high-resolution molecular portrait of coffee: A gateway to insights into its roasting chemistry and comprehensive authenticity profiles.

The direct-infusion of 130 coffee samples into a Fourier-transform ion cyclotron mass spectrometer (FT-ICR-MS) provided an ultra-high resolution perspective on the molecular complexity of coffee: The exceptional resolving power and mass accuracy (± 0.2 ppm) facilitated the annotation of unambiguous molecular formulas to 11,500 mass signals. Utilizing this molecular diversity, we extracted hundreds of compound signals linked to the roasting process through guided Orthogonal Partial Least Squares (OPLS) analysis. Visualizations such as van Krevelen diagrams and Kendrick mass defect analysis provided deeper insights into the intrinsic compositional nature of these compounds and the complex chemistry underlying coffee roasting. Predictive OPLS-DA models established universal molecular profiles for rapid authentication of Coffea arabica versus Coffea canephora (Robusta) coffees. Compositional analysis revealed Robusta specific signals, indicative of tryptophan-conjugates of hydroxycinnamic acids. Complementary LC-ToF-MS2 confirmed their compound class, building blocks and structures. Their water-soluble nature allows for application across raw and roasted beans, as well as in ready-made coffee products.

Inhibitory effects of polyphenols on the Maillard reaction in low lactose milk and the underlying mechanism.

In this study, low lactose milk (LLM) was heat-treated under different conditions and stored at 4, 25 and 37°C for 15 d, after which the changes in the Maillard reaction (MR) of LLM were investigated. The contents of α-dicarbonyl compounds and 5-hydroxymethylfurfural(5-HMF) in LLM after the addition of polyphenols were determined via HPLC, and the inhibitory effects of 3 different concentrations of epigallocatechin gallate (EGCG), dihydromyricetin (DMY), and procyanidin (PC) on the MR of LLM were studied. The fluorescence intensity of LLM was measured at 290, 300 and 310 K, the fluorescence quenching types and binding constants of PC on casein were investigated, and thermodynamic analysis was carried out. These results suggest that the optimal heat treatment conditions were 80°C for 15 s and that the optimal storage conditions were 4°C. In the α-dicarbonyl compound capture and 5-HMF inhibition tests, PC had the greatest inhibitory effect at a concentration of 0.2 mg/mL, with an inhibition rate of 48.19%. Therefore, PC is more stable than the other 2 polyphenols. The mechanism of inhibition involves the formation of matrix complexes between PC and casein in LLM, resulting in static quenching of the LLM and thus a reduction of the inhibitory effect. The thermodynamic analysis revealed that the binding of PC to casein was an exothermic reaction, and the combination of the 2 was driven mainly by hydrogen bonding and van der Waals forces. This study lays a theoretical foundation for the development of LLM.

Effect of hot-air drying processing on the volatile organic compounds and maillard precursors of Dictyophora Rubrovalvata based on GC-IMS, HPLC and LC-MS.

The dynamic changes in volatile organic compounds (VOCs), reducing sugars, and amino acids of Dictyophora rubrovalvata (DR) at various drying temperatures were analyzed using GC-IMS, HPLC, and LC-MS. Orthogonal partial least squares discriminant analysis (OPLS-DA) combined with VOCs indicated that drying temperature of 80 °C was optimal. Variable importance in the projection (VIP) and relative odor activity value (ROAV) were employed to identify 22 key VOCs. The findings suggested that esters played a predominant role among the VOCs. Pearson correlation analysis revealed that serine (Ser), glutamine (Gln), lysine (Lys), alanine (Ala), threonine (Thr), glutamic acid (Glu), asparagine (Asn), ribose, and glucose were closely associated with the formation of esters, aldehydes, ketones, pyrimidines, and pyrazines. In conclusion, this study laid a foundational theory for elucidating the characteristics aroma substances and their production pathways, providing a valuable reference for analysing the flavor characteristics of DR.

Enhanced anti-inflammatory effect of fish myofibrillar protein by introducing pectin oligosaccharide and its molecular mechanisms.

This study investigated the efficacy of glycation with edible uronic acid-containing oligosaccharides via the Maillard reaction to enhance the anti-inflammatory effect of fish myofibrillar protein (Mf). Lyophilized Mf was reacted with pectin oligosaccharide (PO, half of the total protein weight) at 60 °C and 35 % relative humidity for up to 12 h to produce glycated Mf (Mf-PO). After pepsin and trypsin digestion, the anti-inflammatory effect was assessed by measuring the secretions of proinflammatory cytokines in LPS-stimulated RAW 264.7 macrophages, and the anti-inflammatory effect of Mf was enhanced by PO-glycation without marked lysine loss and browning. The effects on the expressions of genes related to the LPS-stimulated signaling pathway in macrophages were also examined. PO-glycation suppressed LPS-stimulated inflammation by suppressing expression of cd14 and enhancing suppressive effect of Mf on the TLR4-MyD88-dependent inflammatory signaling pathway. Therefore, as an edible reducing sugar, PO could be an effective bioindustrial material for developing anti-inflammatory Mf.

Balancing Maillard reaction products formation and antioxidant activities for improved sensory quality and health benefit properties of pan baked buns.

This study investigated the impact of processing temperatures (190 °C, 210 °C, and 230 °C) and durations (7 min, 10 min, and 14 min) on the formation of Maillard reaction products (MRPs) and antioxidant activities in pan baked buns. Key Maillard reaction indicators, including glyoxal (GO), methylglyoxal (MGO), 5-hydroxymethylfurfural (5-HMF), melanoidins, and fluorescent advanced glycation end products (AGEs) were quantified. The results demonstrated significant increases in GO, MGO, 5-HMF contents (p < 0.05), and antioxidant activities (p < 0.05) when the buns were baked at 210 °C for 14 min, 230 °C for 10 min and 14 min. However, the interior MRPs of baked buns were minimally affected by the baking temperature and duration. Prolonged heating temperatures and durations exacerbated MRPs production (43.8 %-1038 %) in the bottom crust. Nonetheless, this process promoted the release of bound phenolic compounds and enhanced the antioxidant activity. Heating induces the thermal degradation of macromolecules in food, such as proteins and polysaccharides, which releases bound phenolic compounds by disrupting their chemical bonds within the food matrix. Appropriate selections of baking parameters can effectively reduce the formation of MRPs while simultaneously improve sensory quality and health benefit of the pan baked buns. Considering the balance between higher antioxidant properties and lower MRPs, the optimal thermal parameters for pan baked buns were 210 °C for 10 min. Furthermore, a normalized analysis revealed a consistent trend for GO, MGO, 5-HMF, fluorescent AGEs, and melanoidins. Moreover, MRPs were positively correlated with total contents of phenolic compounds, ferric-reducing antioxidant power (FRAP), and color, but negatively correlated with moisture contents and reducing sugars. Additionally, the interaction between baking conditions and Maillard reactions probably contributed to enhanced primary flavors in the final product. This study highlights the importance of optimizing baking parameters to achieve desirable MRPs levels, higher antioxidant activity, and optimal sensory attributes in baked buns.

Generation of advanced glycation end products from glycated protein or fructose/glyoxal-protein adducts under in vitro simulated gastrointestinal digestion.

Advanced glycation end products (AGEs) are a heterogeneous group of compounds formed both endogenously and exogenously through reactions between reducing sugars and amino acids within the proteins. The digestive tract may also serve as a site for endogenous AGEs generation. This study examined whether additional AGEs are formed during the digestion of glycated protein diets and meal-resembling systems (dietary proteins with fructose or glyoxal). The digestion of glycated protein showed that free AGEs were gradually released, but no additional AGEs were generated. In contrast, co-digestion of dietary proteins with fructose or glyoxal resulted in the formation of additional AGEs, and the reaction substrates (fructose or glyoxal) were depleted during digestion. Additionally, the lysine released from proteins decreased, leading to a loss of nutritional value of the food during co-digestion. The formation of AGEs and the depletion of essential amino acids in the gut may have significant implications for human health.

Baby Foods: 9 Out of 62 Exceed the Reference Limits for Acrylamide.

Acrylamide (AA) is a contaminant resulting from the Maillard reaction and classified by the International Agency for Research on Cancer (IARC) as a probable carcinogen in Group 2A, with proven neurotoxic effects on humans. European Union (EU) Regulation No. 2017/2158 is currently in force, which establishes measures meant to reduce AA levels in food and sets reference values, but not legal limits, equal to 40 and 150 µg/kg AA in processed cereal-based foods intended for infants and young children and in biscuits and rusks, respectively. For this reason, sixty-two baby foods were analyzed using ultra-high performance liquid chromatography with diode array detector and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-Q-TOF/MS) to check whether industries were complying with these values, even though AA control is not legally mandatory. In total, 14.5% of the samples exceeded the reference values; these were homogenized chicken products (211.84 ± 16.53, 154.32 ± 12.71, 194.88 ± 7.40 µg/kg), three biscuits (276.36 ± 0.03, 242.06 ± 0.78, 234.78 ± 4.53 µg/kg), a wheat semolina (46.07 ± 0.23 µg/kg), a homogenized product with plaice and potatoes (45.52 ± 0.28 µg/kg), and a children's snack with milk and cocoa (40.95 ± 0.32 µg/kg). Subsequently, the daily intake of AA was estimated, considering the worst-case scenario, as provided by the consumption of homogenized chicken products and biscuits. The results are associated with margins of exposure (MOEs) that are not concerning for neurotoxic effects but are alarming for the probable carcinogenic effects of AA.

Study on Selenium Assimilation and Transformation in Radish Sprouts Cultivated Using Maillard Reaction Products.

The organic selenium (Se), particularly in the form of selenoamino acids, in non-edible sections or by-products of Se-enriched plants, has the potential to generate Maillard reaction products (MRPs) during thermal treatment or fermentation. To elucidate the recycling process of organic selenium in foods and improve the utilization rate of Se, the biotransformation of organic selenium was studied by the cultivation of edible radish sprouts with Se-MPRs. Maillard reactions were simulated using selenoamino acids (SeAAs; selenomethionine and methylselenocysteine) and reducing sugars (glucose and fructose) for preparing Se-MRPs. The structures of the possible dehydrated Se-MRPs were analyzed using a HPLC-ESI-MS/MS system based on their fragmentation patterns and Se isotopic characteristics. Se absorption by the radish sprouts cultivated using Se-MRPs was estimated by the corresponding Se in the SeAAs and the total Se contents. The capabilities of SeAA transformation and total Se assimilation by the sprouts were related to the substrate composition during the Se-Maillard reaction. A particular Se-MRP (selenomethionine + fructose) increased SeAAs transformation by 33.8% compared to selenomethionine. However, glucose and fructose seemed to inhibit the transformation of the Se-MRPs to SeAAs by 10.0 to 59.1% compared to purified Se-MRPs. These results provide key references for the efficient utilization of organic Se in the cultivation of Se-enriched sprouts.

Effect of Mono- and Polysaccharide on the Structure and Property of Soy Protein Isolate during Maillard Reaction.

As a protein extracted from soybeans, soy protein isolate (SPI) may undergo the Maillard reaction (MR) with co-existing saccharides during the processing of soy-containing foods, potentially altering its structural and functional properties. This work aimed to investigate the effect of mono- and polysaccharides on the structure and functional properties of SPI during MR. The study found that compared to oat ß-glucan, the reaction rate between SPI and D-galactose was faster, leading to a higher degree of glycosylation in the SPI-galactose conjugate. D-galactose and oat ß-glucan showed different influences on the secondary structure of SPI and the microenvironment of its hydrophobic amino acids. These structural variations subsequently impact a variety of the properties of the SPI conjugates. The SPI-galactose conjugate exhibited superior solubility, surface hydrophobicity, and viscosity. Meanwhile, the SPI-galactose conjugate possessed better emulsifying stability, capability to produce foam, and stability of foam than the SPI-ß-glucan conjugate. Interestingly, the SPI-ß-glucan conjugate, despite its lower viscosity, showed stronger hypoglycemic activity, potentially due to the inherent activity of oat ß-glucan. The SPI-galactose conjugate exhibited superior antioxidant properties due to its higher content of hydroxyl groups on its molecules. These results showed that the type of saccharides had significant influences on the SPI during MR.

Protein-bound and free glycation compounds in human milk: A comparative study with minimally processed infant formula and pasteurized bovine milk.

The role of the Maillard reaction and the accumulation of non-enzymatic glycation compounds in human milk have been scarcely considered. In this study, we investigated the proteins most susceptible to glycation, the identity of the corresponding modified residues and the quantitative relationship between protein-bound and free glycation compounds in raw human milk and, for comparison, in minimally processed infant formula and pasteurized bovine milk. In human milk, total protein-bound lysine modifications were up to 10% of the counterparts in infant formula, while Nε-carboxymethyllysine reached up to 27% of the concentration in the other two products. We demonstrated that the concentration of free pyrraline and methylglyoxal-hydroimidazolone were of the same order of magnitude in the three milk types. Our results delineate how the occurrence of some glycation compounds in human milk can be an unavoidable part of the breastfeeding and not an exclusive attribute of infant formulas and pasteurized bovine milk.

Husk Separation (Kubessa Method) Impacts the Aging Chemistry of Beer.

The removal of husks before the mashing process, also known as the Kubessa method, is an established brewing practice often positively associated with smoothness and better flavor-stability of beer. Empirical evidence on the effect of the Kubessa method on beer, however, has been lacking. Similarly, our study's comprehensive analysis of established brewing attributes revealed that traditional methods do not fully capture the impact of husk separation in beer brewing. Conclusive evidence of the Kubessa method's impact on beer aging chemistry was obtained through ultrahigh resolution mass spectrometry (FT-ICR-MS), revealing intricate molecular details inaccessible to conventional analytical techniques. The compositional information on thousands of molecules in Kubessa beer was resolved and compared to whole malt mashing. Machine learning algorithms applied to aging experiments identified over 500 aging-related compounds inhibited by husk separation. Complementary Time of flight mass spectrometry (ToF-MS) coupled with chromatography further confirmed that the mashing of husks introduces sulfur-containing lipid compounds. These significant differences in the beer composition provide valuable insights for further investigation into the staling protective effect of husk-separation (Kubessa process) during beer production, as empirically demonstrated in this work.

Insight into protein cross-linking and casein polymerization in pre- and post-hydrolyzed lactose-free UHT milk during long-term storage.

During processing and storage of both conventional and lactose-hydrolyzed UHT milk (LHM), aggregation of milk proteins occurs. Protein aggregation can inter alia occur via non-reducible covalent cross-links derived from either Maillard or dehydroalanine (DHA) pathways. To study this further in relation to processing method and lactase enzyme purity, LHM was produced using 3 different lactase preparations, with lactase enzymes added in a dairy setting either before (pre-hydrolysis) or after (post-hydrolysis) UHT treatment. The prepared LHM types were subsequently stored at either 25°C or 35°C for up to one year. Mass spectrometry was used to absolutely quantify the level of furosine, N-ɛ-(carboxymethyl)lysine (CML) and N-ɛ-(carboxyethyl)lysine (CEL), lanthionine (LAN) and lysinoalanine (LAL) in these products using a newly developed method on Triple Q for these processing-induced markers. The results showed higher levels of Maillard related processing markers in pre-hydrolyzed LHM compared with post-hydrolyzed LHM and conventional UHT milk which, on the other hand, contained higher concentrations of DHA-derived cross-links. Proteomics of collected particles from asymmetrical flow field-flow fractionation (AsFlFFF) in combination with gel electrophoresis indicated presence of intra-micellar cross-links during storage, for especially larger particles involving αS1- and αS2-caseins.

Maillard reaction products inhibit lipid oxidation by regulating myoglobin stability in washed muscle model.

Lipid oxidation significantly contributes to muscle deterioration, with heme protein oxidation playing a crucial role in this process. This study investigated the inhibition of heme protein oxidation by Maillard reaction products (MRPs) using a washed muscle model combining washed carp with myoglobin (Mb). Protein oxidation products, protein texture, and lipid oxidation levels were assessed. Results showed that metmyoglobin (MetMb) is a primary driver of lipid oxidation in meat, likely due to Mb oxidation, exposing hydrophobic groups that bind to lipids. MRPs at concentrations of 0.5% and 1% effectively inhibited Mb oxidation. Specifically, treatment with 1% MRPs reduced MetMb formation by 15.38%, protein carbonyl content by 6.53%, hydroxyl radical content by 20.37%, protein aggregation by 40.81%, and particle size by 36.95% during later storage stages, thereby preserving Mb stability. In the Mb-mediated oxidation model, 1% MRPs inhibited the formation of primary and secondary oxidative metabolites by 59.47% and 68.19%, respectively, while maintaining muscle tissue texture integrity. PRACTICAL APPLICATION: The antioxidation of Maillard reaction products (MRPs) improves the stability of common carp. By inhibiting the autoxidation of myoglobin and lipid, MRPs help preserve the texture and color of fish muscle while extending its shelf life. This study provides a valuable reference for effectively controlling lipid oxidation in refrigerated fish products and enhancing their overall quality.

The Characterization of a Low-Calorie and Lactose-Free Brown Fermented Milk by the Hydrolysis of Different Enzymatic Lactose.

The adoption of brown fermented milk in the normal diet and daily beverages is accompanied by significant sugar intake and a high public health burden. To reduce the sugar content in dairy products while maintaining optimal nutritional properties, a novel low-calorie, lactose-free brown fermented milk was developed through enzymatic hydrolysis and the Maillard reaction. The optimal product was achieved using low-temperature lactase, where the lactose and glucose content were reduced 33-fold and 2.4-fold to 0.06 g/100 g and 13.32 g/L, respectively, meeting the criteria for being lactose-free (<0.5 g/100 g). Meanwhile, hazardous compounds such as 5-hydroxymethylfurfural and 3-deoxyglucosone were reduced by more than 20%. After 28 days of storage, the water-holding capacity and suspension stability remained notably stable, and the protein composition was also more enriched compared to commercial milk. It is expected that this low-calorie dairy product may promote growth in the dairy market.

Mechanochemistry in Glycation Research.

Mechanochemistry by milling has recently attracted considerable interest for its ability to drive solvent-free chemical transformations exclusively through mechanical energy and at ambient temperatures. Despite its popularity and expanding applications in different fields of chemistry, its impact on Food Science remains limited. This review aims to demonstrate the specific benefits that mechanochemistry can provide in performing controlled glycation, and in "activating" sugar and amino acid mixtures, thereby allowing for continued generation of colors and aromas even after termination of milling. The generated mechanical energy can be tuned under specific conditions either to form only the corresponding Schiff bases and Amadori compounds or to generate their degradation products, as a function of the frequency of the oscillations in combination with the reactivity of the selected substrates. Similarly, its ability to initiate the Strecker degradation and generate pyrazines and Strecker aldehydes was also demonstrated when proteogenic amino acids were milled with glyoxal.

Novel Pink Pigments Produced by Thermal Interaction of Theaflavins, Theanine, and Glucose: Color Formation, Isolation, and Structural Characterization.

A color-deepening effect of theaflavins on the theanine-glucose thermal reaction model was revealed. Generated chromogenic intermediates in the initial stage and an accelerated browning rate through the promoted degradation of theanine-glucose Amadori rearrangement product in the intermediate and final stages are responsible for the color-deepening effect. Four pink-to-red theaflavin-theanine intermediates were verified as theaflavinies referencing the nuclear magnetic resonance and liquid chromatography-mass spectrometry information on theaflavins and l-theanine, including one accurately identified as theaflavinie 4. Theaflavinie 4 showed two maximum absorption peaks at 401 and 506 nm with parallel intensities, which resulted in a significant dichromic color change from pale pink to orange and red. Theaflavinies also could undergo further thermal reactions to yield brown polymers under higher temperatures (130 and 140 °C). This research provided new insight into realizing thermally formed polymers during black tea processing, which may be formed by oxidation products and amino acids or proteins through non-enzymatic thermal reactions.

Analysis of volatile compounds and α-dicarbonyl compounds in Arabica coffee soaked with various organic acids.

In this study, volatile compounds and α-dicarbonyl compounds (α-DCs), such as glyoxal (GO), methylglyoxal (MGO), and diacetyl (DA), were analyzed in Arabica coffee prepared from Arabica green coffee beans presoaked in six organic acid solutions. The ratio of volatile compounds in samples was 18.06 to 0.6 (peak area of each peak/peak area of internal standard). Succinic acid pretreated Arabica had the highest concentration of volatile compounds, 128.9% higher than without pretreatment. The level of total α-DCs ranged from 12.90 to 100.32 µg/mL. Detected levels of GO, MGO, and DA ranged from 0.81 to 7.74, from 18.53 to 89.08, and from 0.43 to 6.74 µg/mL, respectively. Organic acid pretreatment increased the amounts of volatile compounds and lowered the concentrations of α-DCs compared to without pretreatment. The results obtained in this study would be useful for increasing the flavor of Arabica coffee and decreasing α-DCs. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01592-2.