Characterization of silver carp (Hypophthalmichthys molitrix) myosin protein glycated with konjac oligo-glucomannan

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.

Characterization of O/W emulgels based on whey protein-alginate-inulin coacervates: Influence of temperature and ultrasound as protein preconditioning process

Preconditioning processes in proteins play a crucial role in enhancing their functional properties as surface active agents. Whey protein isolate (WPI, 20 wt%) was preconditioned via temperature (WPIT, 90 °C) or ultrasound (WPIUS, 20 kHz, 80 % amplitude). FTIR and zeta potential analysis demonstrated the effect of the preconditioning process on the secondary structure and surface properties of WPI. WPI-Alginate:Inulin (AI) complex coacervates (CCWPI:AI) were formed at pH 3.0 using WPIT and WPIUS, and the associative electrostatic interactions between WPI-AI led to coacervation yields >90 %, influenced by the preconditioning process employed. Viscoelastic properties outlined a predominantly solid-like behavior (G´ > G"). The CCWPI:AI system based on WPIT showed enhanced strength and gel-like structure compared to the WPIUS-based system. Oil-in-water (O/W) emulgels were formed and stabilized with the CCWPI:AI complexes, exhibiting spherical droplets (93.3-292.8 μm), whereas texture and rheological properties highlighted the formation of gel-like systems. The centrifugation STEP technology was used to evaluate the physical stability of emulgels, WPIT-based emulgels displayed superior stability against creaming than untreated WPI and WPIUS-based emulgels. These findings provide a basis for developing emulgels with prolonged stability and tunable functional properties, tailoring enhanced viscoelastic and texture attributes to meet specific needs for industrial applications where gel-like properties are pursued.

Glycosylation modification: A promising strategy for regulating the functionalities of myofibrillar proteins

Myofibrillar proteins (MPs), the most important proteins in muscle, play a vital role in the texture, flavor, sensory and consumer acceptance of final muscle-based food products. Over the past several decades, conjugation of carbohydrates to MPs via glycosylation is of particular interest due to the substantial enhancement in MPs characteristics. Studying the covalent interactions between carbohydrates and MPs under various processing conditions and molecular mechanisms by which carbohydrates affect the functionalities of MPs can introduce new perspectives for design and production of muscle-based foods. However, there is no insightful and comprehensive summary of the structural, physicochemical and functional characteristics changes of MPs induced by glycosylation modification and how these changes can be adopted to potentially promote the science-based development of tailor-made muscle foods. Based on this, the functionalities of MPs as well as their practical limiting issues are initially highlighted. A comprehensive overview of fabrication strategies is then introduced. Additionally, changes in the structural and functional properties of MPs regulated by glycosylation have also been carefully summarized. On this basis, the research limitations to be solved and our perspectives for the future development of muscle-based foods are put forward.

Glycation with uronic acid-type reducing sugar enhances the anti-inflammatory activity of fish myofibrillar protein via the Maillard reaction

The role of carboxyl group in uronic acid in enhancing the anti-inflammatory activity of fish myofibrillar protein (Mf) was investigated, when lyophilized Mf was reacted with various reducing sugars at 60 °C and 35% relative humidity through the Maillard reaction. After pepsin and trypsin digestion, the anti-inflammatory activity was evaluated by measuring the secretions of tumor necrosis factor-α, interleukin-6, interleukin-1β, and nitric oxide in lipopolysaccharide-stimulated RAW 264.7 macrophage. The anti-inflammatory activity of Mf was not affected by glycation with glucose or galactose, whereas strongly enhanced by glycation with uronic acid-type reducing sugars: glucuronic acid, galacturonic acid, and alginate oligosaccharide. These results indicate that the presence of carboxyl group in reducing sugar is important for enhancing the anti-inflammatory activity of Mf. This study also shows that the enhanced effect could depend upon the number of carboxyl group in bound reducing sugar.

Changes in partial properties of glycosylated egg white powder during storage

BACKGROUND

Glycosylation is an effective method to modify protein. However, there is a lack of research on the property changes of glycosylated protein during storage. In the present study, the changes in the physicochemical, functional, and structural properties of xylo-oligosaccharide (XOS) glycosylated egg white powder (EWP) (XOS-EWP conjugates) prepared with different glycosylation conditions (XOS/EWP ratio and reaction time) were investigated when stored at 25 °C and 60% relative humidity.

RESULTS

In the 12 weeks of storage, the degree of grafting, browning, and the formation of Maillard reaction products of XOS-EWP conjugates increased. The increase in XOS/EWP ratio and reaction time led to an increase in protein aggregation, though a decrease in solubility, due to increased degree of glycosylation and structural changes. Furthermore, improved gel hardness of XOS-EWP conjugates deteriorated, while improved emulsification ability was kept stable during storage. For the sample with a lower XOS/EWP ratio and reaction time, the gel hardness and emulsifying properties underwent little or no deterioration even improving during storage. The results could be attributed to the limited degree of glycosylation, further unfolding of the protein structure, increased surface hydrophobicity of protein, and improved thermal characteristics.

CONCLUSION

During storage, the Maillard reaction would continue to occur in the glycosylated EWP, further affecting the performance of modified EWP. Modified EWP prepared under different glycosylation conditions performed differently during storage. Modified EWP with a larger XOS/EWP ratio and reaction time meant it was harder to maintain good performance. Modified EWP with a smaller XOS/EWP ratio and reaction time changed significantly to better performances. © 2022 Society of Chemical Industry.

Comparison of Maillard-Type Glycated Collagen with Alginate Oligosaccharide and Glucose: Its Characterization, Antioxidant Activity, and Cytoprotective Activity on H2O2-Induced Cell Oxidative Damage

To improve the antioxidant activity of collagen molecules using Maillard-type glycation, the relation between antioxidant activity and progress indexes for the Maillard reaction must be understood. In this study, lyophilized tilapia scale collagen was mixed with a half weight of alginate oligosaccharide (AO) or glucose and incubated at 60 °C and 35% relative humidity for up to 18 h to produce the Maillard-type glycated collagen (C-AO and C-Glu, respectively). As glycation progressed, the amount of conjugated sugar coupled with UV-vis absorbance at 294 nm and 420 nm increased more rapidly in C-Glu than in C-AO, and the available lysine decreased rapidly in C-Glu compared with C-AO. The early-to-middle- and late-stage products of the Maillard reaction were involved in enhanced antioxidant activity of digested C-AO and digested C-Glu, respectively. Additionally, C-AO acquired the antioxidant activity without marked available lysine loss. The cytoprotective effect of collagen in H₂O₂-induced damage was enhanced by glycation, achieved by reducing malondialdehyde content and increasing superoxide dismutase and catalase activities. These results indicate that AO is an excellent reducing sugar that enhances the health benefits of collagen without excessive loss of lysine, which is a nutritional problem of the Maillard-type glycation.

Effects of Enzymatic Konjac Glucomannan Hydrolysates on Textural Properties, Microstructure, and Water Distribution of Grass Carp Surimi Gels

This present work investigated the influence of konjac glucomannan (KGM) enzymatic hydrolysates on the textural properties, microstructure, and water distribution of surimi gel from grass carp (Ctenopharyngodon idellus). The molecular weight (M_w) of KGM enzymatic hydrolyzed by β-dextranase degraded from 149.03 kDa to 36.84 kDa with increasing enzymatic time. In the microstructure of surimi gels, KGM enzymatic hydrolysates with higher M_w showed entangled rigid-chains, while KGM enzymatic hydrolysates with lower M_w (36.84 kDa) exhibited swelled fragments. The hardness of surimi gel with a decline in KGM M_w exhibited first increasing then decreasing trends, while the whiteness of surimi gel increased. When KGM M_w decreased, the immobile water percentage of total signals decreased from 96.7% to 93.6%, and mobile water increased from 3.03% to 6.37%. In particular, the surimi gel with the addition of K2 showed better gel strength and water distributions. KGM enzymatic hydrolysates are expected to be used as a low-calorie healthy gel enhancer in surimi processing.

Maillard Reaction Induced Changes in Allergenicity of Food

Food allergy is increasing in prevalence, posing aheavier social and financial burden. At present, there is still no widely accepted treatment for it. Methods to reduce or eliminate the allergenicity of trigger foods are urgently needed. Technological processing contributes to producing some hypoallergenic foods. Among the processing methods, the Maillard reaction (MR) is popular because neither special chemical materials nor sophisticated equipment is needed. MR may affect the allergenicity of proteins by disrupting the conformational epitope, disclosing the hidden epitope, masking the linear epitope, and/or forming a new epitope. Changes in the allergenicity of foods after processing are affected by various factors, such as the characteristics of the allergen, the processing parameters, and the processing matrix, and they are therefore variable and difficult to predict. This paper reviews the effects of MR on the allergenicity of each allergen group from common allergenic foods.

Characterization of silver carp myosin glycated with phosphorylated konjac oligo-glucomannan

BACKGROUND

Myosin (Ms) is abundant in fish meat, but it has limited application in the food industry because of its low solubility and thermal stability. Our previous reports found that these functional properties of Ms can be significantly improved after glycation with konjac oligo-glucomannan (KOG). However, the effects of phosphorylated KOG (PKOG) on physicochemical, structural and functional properties of silver carp Ms are still unknown.

RESULTS

This study characterized the silver carp Ms protein glycated with PKOG at 50 °C and 75% relative humidity for 48 h. As degree of phosphorylation increased, free amino content increased, whereas degree of grafting decreased. Meanwhile, isoelectric point (pI) reduced, however, PKOGs showed no differences in pI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis suggested the formation of glycoconjugates, and scanning electron microscopy revealed thinner flakes and uneven appearance of glycoconjugates. Fourier transform infrared spectroscopy indicated that the amide I, II and III bands of Ms were changed by the glycation. Ms became highly soluble in 0.5 mol L^-1 NaCl with increased phosphate addition in PKOGs. Thermal stability of Ms was effectively improved when heated at 80 °C for 60 min.

CONCLUSION

Glycation with appropriate PKOG might be a promising method for Ms modification because of the resulting improvement in solubility and thermal stability. © 2021 Society of Chemical Industry.

Hermetia illucens Protein Conjugated with Glucose via Maillard Reaction: Antioxidant and Techno-Functional Properties

The food industry is considering novel sources of proteins with enhanced functionalities to meet the increasing demand and population growth. Edible insect proteins have emerged as an alternative that is environmentally friendly and economically viable and thus could make a significant contribution to global food security. This study was aimed to establish the effect of conjugation via the Maillard reaction on the antioxidant and techno-functional properties of black soldier fly larvae protein concentrate. Reaction mixtures containing black soldier fly larvae protein concentrate and glucose (2 : 1 weight ratio) were wet-heated at 50, 70, and 90°C for 2, 4, 6, 8, and 10 h, respectively, with an initial pH of 9. The results showed that the browning indices of the black soldier fly larvae-glucose (BSFL-Glu) model system increased with an increase in reaction time and temperature, with conjugates formed at 90°C exhibiting the highest browning intensity at 420 nm. At 50°C, the DPPH-RS of the conjugates ranged from 15.47 to 32.37%. The ABTS⁺ radical scavenging activity of BSFL-Glu conjugates produced at 90°C exhibited significantly (p < 0.05) higher scavenging activity as a function of reaction time. The foaming capacity of BSFL-Glu conjugates produced at 70°C showed a significant increase (p < 0.05) as a function of reaction time. Principal component analysis was applied to browning and antioxidant indices. Component 1 of the score plot accounted for 89%, while component 2 accounted for 8% of the observed variability and allowed discrimination/differentiation of the samples based on the heating temperature. These findings provide a practical means to improve the functionality of novel edible insect proteins for food application.

Ameliorative effects of L-arginine? On heat-induced phase separation of Aristichthys nobilis myosin are associated with the absence of ordered secondary structures of myosin

This investigation aimed to study the potential mechanism of L-arginine (L-Arg) on the heat-induced phase separation phenomenon of myosin from the perspective of conformational changes of myosin. L-Arg ameliorated the phase separation of myosin after a two-step heating procedure via suppression of heat-induced aggregation of myosin. The effect of L-Arg on the heating of myosin at high temperatures (75-85 °C) was more pronounced than that in the setting stage (35-45 °C), suggesting that the ameliorative effects of L-Arg on the heat-induced phase separation of myosin are mainly attributed to the inhibition of rod-rod cross-linking between denatured myosin molecules. Additionally, L-Arg without pH modification exhibited an increased ability to suppress the gelation of myosin compared with pH modification, indicating that both pH effects and the particular structure of L-Arg play noticeable roles in the suppression of myosin gelation. Far-UV circular dichroism, intrinsic fluorescence spectroscopy and differential scanning calorimetry demonstrated that L-Arg induced the absence of ordered secondary structures of myosin molecules, especially β-sheets, and thus generated a looser protein structure, which may represent the dominant suppression mechanisms of L-Arg on the heat-induced aggregation of myosin. This work provided support for the use of L-Arg as a food additive, and the results of this study will be attractive to the meat and beverage products.

Structural and antimicrobial properties of Maillard reaction products in chicken liver protein hydrolysate after sonication

This study aimed to investigate the structural and antimicrobial properties of Maillard reaction products (MRPs) in chicken liver protein (CLP) and its hydrolysate (CLPH) after sonication (SCLPH). The MRPs of CLP (CLPM), CLPH (CLPHM) and SCLPH (SCLPHM) were analyzed by several spectrometric techniques. The molecular weights of the CLPHM and SCLPHM were primarily between 1.35 kDa and 17 kDa. Moreover, the molecular weights in the CLPHM and SCLPHM below 1.35 kDa were increased, which indicated that cross-linking and thermal degradation occurred during the Maillard reaction (MR). The SCLPHM showed an obvious network skeleton, and the surface had many small crystal-shaped particles after ultrasound treatment and MR by scanning electron microscopy. The SCLPHM had more negative charges than the CLPHM, thus effectively inhibiting the growth of S. saprophyticus and E. coli. MR and ultrasound treatment could be a promising technology to expand the application prospects of low-value meat byproducts.

Preparation and characterization of carboxymethyl chitosan/collagen peptide/oxidized konjac composite hydrogel

Medical dressings are used to protect damaged skin from external factors and provide a good healing environment. Hydrogels are aggregates of hydrophilic polymers and water that have a three-dimensional space and can absorb large amounts of water. It has been widely studied in the field of biomedical materials. In this study, we prepared a novel composite hydrogel combined carboxymethyl chitosan, collagen peptide and oxidized konjac, all three materials have been shown to be biocompatible. Then, we set up different hydrogels and tested hydrogels with different proportions. The structures of CMCS (carboxymethyl chitosan)/COP (collagen peptide)/OKGM (oxidized konjac) hydrogels were characterized by IR, NMR, X-ray diffraction and SEM. The effects of hydrogels on the growth of NS-FB and HS-FB cells were studied in vitro. The results of these tests show that the composite hydrogel has excellent mechanical properties and biological activity, and has potential application in wound dressing field.

Optimization on production of konjac oligo-glucomannan and their effect on the gut microbiota

Konjac glucomannan (KGM) is a polysaccharide extracted from Amorphophallus konjac, and its degradation product is konjac oligo-glucomannan (KOG). The aim of this study was to produce KOG from KGM and to evaluate its effect on the gut microbiota in fecal batch culture. KOG was produced by enzymatic hydrolysis using β-mannanase. The optimum conditions were as follows: reaction temperature of 48°C, reaction time of 4 hr, pH of 5.5 and E/S of 0.05% followed by purification step using 3,000 NMWC ultrafiltration (UF) membrane pore size. The effect of KOG on changes in human fecal bacterial populations and short-chain fatty acids (SCFAs) production was evaluated. The results showed that low-molecular weight KOG (LKOG) from purification step with concentration of 9.54 mg/ml, and a prebiotic index (PI) of 0.76 was successfully produced. LKOG can enhance the production of butyric acid in the colon with the highest concentration (8.24 mM) found at 72 hr fermentation.

Chemical characterization of the glycated myofibrillar proteins from grass carp (Ctenopharyngodon idella) and their impacts on the human gut microbiota in vitro fermentation

Glycation greatly increased the anti-digestibility of myofibrillar proteins derived from grass carp, and affected the production of SCFAs and the microbial community structures inin vitrofecal fermentation.