Degree Of Glycation Research Articles

Cricket protein conjugated with different degrees of polymerization saccharides by Maillard reaction as a novel functional ingredient

This study investigated the effects of different saccharides (inulin and fructooligosaccharides (FOS)), pH (8–10) and thermal treatment time (6–24 h) at 70 °C on the structural, functional properties and antioxidant activities of conjugated cricket protein (CCPs) by wet heating Maillard reaction (MR). Results suggested that the browning intensity, color development and degree of glycation were significantly increased (p < 0.05) under increasing thermal treatment with FOS. SDS-PAGE and FTIR confirmed the formation of a higher molecular weight of CCPs. Water solubility, oil holding capacity, emulsifying properties, and antioxidant properties of CCPs were all superior to the unconjugated products. However, the over-conditioning (treatment time > 6 h, pH > 9) in MR could contribute to a significant decrease (p < 0.05) of CCPs functional properties. The results suggested that the conjugation of cricket protein isolate (CPI) with MR is the most promising way to improve cricket protein properties for food industry applications.

Ultra-stable high internal phase emulsions stabilized by protein-anionic polysaccharide Maillard conjugates

This paper reports the production of O/W high internal phase emulsions (HIPEs) using protein-anionic polysaccharide Maillard conjugates. First, Maillard conjugates were prepared from soy protein isolate (SPI) or sodium caseinate (SC) proteins and Alyssum homolocarpum seed gum (AHSG) or kappa-carrageenan (kC) polysaccharides. The conjugation process was confirmed and monitored by UV spectrophotometry, Fourier transform infrared, circular dichroism, fluorescence spectroscopies, and differential scanning calorimetry. Under the optimized reaction conditions, SC-AHSG conjugates exhibited the highest glycation degree and emulsifying properties. Next, HIPEs were made using the optimized conjugates, and their microstructure, droplet size, and physical stability were evaluated. The emulsion stabilized by SC-AHSG conjugate had the lowest mean droplet size (363.07 ± 34.56 nm), orderly-packed oil droplets with monomodal distribution, the highest zeta potential (-27.70 ± 0.70 mV), high storage stability (no creaming or oil-off) and was ultra-stable against environmental stresses. Results of this research are helpful for development of emulsion-based foods with novel functionality.

Effect of chitosan oligosaccharide glycosylation on the emulsifying property of lactoferrin

There is fast increasing interest in the development of alimentary protein stabilized emulsions due to their potential applications in functional food fields. This work studied the effect of glycation degree with chitosan oligosaccharide (COS) on the emulsifying properties of lactoferrin (LF) through Maillard reaction. In the present study, SDS-PAGE and FT-IR were used to confirm LF and COS covalently binding together successfully. Intrinsic fluorescence showed that glycation with COS led more hydrophobic groups exposed to the surface of the structure and particle size increase of LF. Emulsions with 50% (v/v) oil phase and protein concentration of 2% (w/v) was fabricated through one-step shear method. Compared with native LF, emulsions stabilized by LF-COS conjugates showed smaller droplet size and lower creaming index (CI). Among these samples, LF-COS conjugates under 4 h had the best emulsifying efficiency and stability, the emulsion droplet size and the CI of which decreased 39.66% and 28.55% compared with LF, respectively. Furthermore, glycation with COS enhanced the interfacial activity of LF leading to more adsorbing amount and forming thicker layer on the droplets and gel network in the emulsions. This finding would make sense to further understand the modification of emulsifying properties of alimentary proteins through glycosylation with saccharides and develop novel protein-based emulsifiers.

Glycation Alters the Fatty Acid Binding Capacity of Human Serum Albumin.

Glycation significantly alters the physicochemical and biofunctional properties of proteins in foods and in vivo. In the present study, human serum albumin (HSA) as the major transporter of fatty acids was modified with glyoxal under physiological conditions. Reversibly albumin-bound glyoxal was removed, and advanced glycation end products were quantitated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The total modification of protein-bound lysine and arginine residues reached up to 4.2 and 9.6%, respectively. The impact of these modifications on the transport capacity of long-chain fatty acids was characterized by spin-labeled fatty acid probes via electron paramagnetic resonance spectroscopy. With increasing degree of glycation, the equivalence of the seven binding sites of native HSA with a dissociation constant of 0.74 ± 0.09 μM was set off with only the three high-affinity sites 2, 4, and 5 remaining (0.46 ± 0.07 μM). The other four sites were shifted to low affinities with significantly higher dissociation constants (1.32 ± 0.35 μM). Tryptic peptide mapping enabled us to relate these findings to molecular changes at specific binding sites. Modification hotspots identified were lysine 351, 286, 159 and arginine 144, 485, 117. Further investigation of plasma protein samples of uremic patients vs healthy controls gave first insights into the in vivo situation.

Effect of glycation on protein structure, amino acid composition and digestibility of silver carp mince

SummaryThis study was to investigate the effects of glycation on the quality of silver carp mince (SCM) proteins. The browning index (BI), sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE), Fourier transform infrared spectroscopy (FTIR), total amino acid composition, chemical score, protein digestibility and reductive power of digested products were determined. The correlation between the degree of glycation, protein structure and protein nutritional quality was analysed. The results showed that the BI value of SCM‐G increased with the increase in heating time. Myosin heavy chain (MHC), myosin light chain (MLC), tropomyosin and actin were the main protein reactants for glycation. Glycation led to the expansion of the secondary structure of SCM proteins. Glycation reduced lysine and cysteine content but did not change the first limiting amino acid (Val) in SCM. The essential amino acid content of glycated SCM remained consistent with the amino acid nutritional requirements for children and above recommended by FAO/WHO. In addition, glycation did not change protein digestibility but significantly increased the reducing power of digested products with increasing degree of glycation. These results provided a theoretical basis for the application of glycation in food processing industry and the development of aquatic products with high nutritional value.

Sensory quality and digestibility evaluation of silver carp sausage glycated with l ‐arabinose

This study focused on the effect of different levels of l-arabinose addition on the sensory quality and digestibility of silver carp sausage by testing color, texture, smell, taste, sensory score, and digestibility. The results showed that the L* value of fish sausage decreased with the increase of l-arabinose, while a* value, b* value, and BI increased. In addition, the hardness, springiness, and chewiness of fish sausage reached the maximum when adding 2% l-arabinose. Principal component analysis results of E-nose and E-tongue data showed that l-arabinose enhanced the aroma and taste profiles. Sensory evaluation found that fish sausage with 2% l-arabinose had the highest overall acceptability. Moreover, the addition of 2% arabinose could better maintain the protein digestibility of fish sausage intact. This study has suggested a promising potential for applying glycation in aquatic product processing and the development of nutritious ready-to-eat fish products using l-arabinose. Novelty impact statement This work investigates the impact of different levels of l-arabinose addition on the color, texture, smell, taste, and digestibility of silver carp sausage. It explains how the change of glycation degree affects the sensory quality and digestibility of silver carp sausage. Fish sausage with good overall acceptability and digestibility was obtained by adding 2% l-arabinose. This work contributes a theoretical basis for applying glycation in aquatic product processing and developing nutritious ready-to-eat fish products using l-arabinose.

Effect of glycation degree on the structure and digestion properties of ovalbumin: A study of amino acids and peptides release after in vitro gastrointestinal simulated digestion

Glycation can improve the functional properties of protein. However, in vitro and animal studies have shown that glycation induced lysine blockage and impaired protein digestibility. This study aimed to explore the effects of different glycation degree on the structure and digestive characteristics of ovalbumin. The results showed that glycation decreased the turbidity and hydrophobicity of the protein and changed the protein structure. Moreover, the results of in vitro simulated digestion revealed that glycation reduced the contents of essential amino acids and total amino acids after digestion. Glycation changed the amino acids and peptides release from the protein by resisting the digestion of digestive enzymes, especially trypsin. In conclusion, this work links glycation, protein digestibility, and the release of amino acids and peptides. This emphasizes the importance of the balance between improving properties and ensuring the digestibility of proteins during food processing.

Genotoxicity of advanced glycation end products in vitro is influenced by their preparation temperature, purification and cell exposure time.

Advanced glycation end products (AGEs) are formed via non-enzymatic reactions between amino groups of proteins and the carbonyl groups of reducing sugars. Previous studies have shown that highly glycated albumin prepared using a glucose-bovine serum albumin (Glu-BSA) model system incubated at 60°C for 6 weeks induces genotoxicity in WIL2-NS cells at 9 days of exposure measured by the cytokinesis-block micronucleus cytome (CBMNcyt) assay. However, this AGE model system is not physiologically relevant as normal body temperature is 37°C and the degree of glycation may exceed the extent of albumin modification in vivo. We hypothesised that the incubation temperature and purification method used in these studies may cause changes to the chemical profile of the glycated albumin and may influence the extent of genotoxicity observed at 3, 6 and 9 days of exposure. We prepared AGEs generated using Glu-BSA model systems incubated at 60°C or 37°C purified using trichloroacetic acid (TCA) precipitation or ultrafiltration (UF) and compared their chemical profile (glycation, oxidation, and aggregation) and genotoxicity in WIL2-NS cells using the CBMNcyt assay after 3, 6 and 9 days of exposure. The number of micronuclei (MNi) was significantly higher for cells treated with Glu-BSA incubated at 60°C and purified via TCA (12 ± 1 MNi/1000 binucleated cells) compared to Glu-BSA incubated at 37°C and purified using UF (6 ± 1 MNi/1000 binucleated cells) after 9 days (P < 0.0001). The increase in genotoxicity observed could be explained by a higher level of protein glycation, oxidation, and aggregation of the Glu-BSA model system incubated at 60°C relative to 37°C. This study highlighted that the incubation temperature, purification method and cell exposure time are important variables to consider when generating AGEs in vitro and will enable future studies to better reflect in vivo situations of albumin glycation.

Effect of different heat treatments on the Maillard reaction products, volatile compounds and glycation level of milk

In this study, the formation of Maillard reaction products and the Maillard reaction sites of milk proteins were studied under different heat treatment conditions. Fifteen samples heated at 75, 90, 105, 120 or 135 °C for 5, 15 or 30 s were selected to investigate the effects of different heat treatment conditions on the Maillard reaction products volatile compounds and protein glycation degree. The contents of fluorescence intensity, furosine, lactulose, and 5-hydroxymethylfural were positively associated with the heat temperature and treatment time. Compared with that of raw milk, the number of glycated proteins increased from 14 to 49 in the milk samples heated at 135 °C for 5 s, and the number of binding sites increased from 47 to 166. These results advance current knowledge about the effect of different heat treatments on the degree of the Maillard reaction and the sensory quality and glycation level of milk.

Comparison of glycation degrees of HbG-Coushatta and HbG-Taipei with HbA using liquid chromatography with tandem mass spectrometry

BackgroundHemoglobin A1c(HbA1c) is widely used to measure glycemic status and control in diabetes testing and treatment and is an important risk factor forcomplications of diabetes. Hemoglobin variants can interfere with the HbA1c testing method by reducing the life span of erythrocytes or due to differences in glycation degrees. In this study, glycation levels of the HbA, HbG-Coushatta, and HbG-Taipei β-chains (βA, βG-Coushatta, and βG-Taipei, respectively) were examined. MethodsBlood samples from heterozygotic patients (HbG-Coushatta/HbA, HbG-Taipei/HbA) were analyzed. Glycation rateswere determined using high-performance liquid chromatography with tandem mass spectrometry. Ratios of glycated βG-Coushatta to glycated βA and glycated βG-Taipei to glycated βA were calculated by comparingareas under the curves from extracted ion chromatograms. ResultsβG-Coushatta and βG-Taipei were 6.08 ± 1.38% and 5.95 ± 0.93% glycated (respectively), which were significantly higher than βA chains(4.55 ± 1.30% and 4.51 ± 0.91%, respectively; p = 0.000). The total glycation degree (α + β) in HbG-Coushatta and HbG-Taipei heterozygotes were estimated to be 9% and 8% higher than those of HbA homozygotes (P＜0.001), respectively. ConclusionβG-Coushatta and βG-Taipei glycation degrees were significantly higher than βA, while the differences in total hemoglobin (α + β) were small and unlikely to impact the clinical interpretation of HbA1c results.

Glycation of soy protein isolate with two ketoses: d‐Allulose and fructose

SummaryModification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d‐Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier‐transform infrared spectroscopy analysis, antioxidant activity experiments and time‐domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d‐Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities.

How Does Glycation Affect Binding Parameters of the Albumin-Gliclazide System in the Presence of Drugs Commonly Used in Diabetes? In Vitro Spectroscopic Study.

In this research, the selected drugs commonly used in diabetes and its comorbidities (gliclazide, cilazapril, atorvastatin, and acetylsalicylic acid) were studied for their interactions with bovine serum albumin—native and glycated. Two different spectroscopic methods, fluorescence quenching and circular dichroism, were utilized to elucidate the binding interactions of the investigational drugs. The glycation process was induced in BSA by glucose and was confirmed by the presence of advanced glycosylation end products (AGEs). The interaction between albumin and gliclazide, with the presence of another drug, was confirmed by calculation of association constants (0.11–1.07 × 104 M−1). The nature of changes in the secondary structure of a protein depends on the drug used and the degree of glycation. Therefore, these interactions may have an influence on pharmacokinetic parameters.

Mechanism on the Allergenicity Changes of α-Lactalbumin Treated by Sonication-Assisted Glycation during In Vitro Gastroduodenal Digestion.

Physical-assisted chemical modification is effective to reduce the allergenicity of α-lactalbumin (ALA). However, there are few in-depth studies on the allergenicity changes of physical-assisted chemical-modified ALA during digestion. The effect of gastroduodenal digestion on the allergenicity changes of ALA treated by sonication-assisted glycation was assessed. Digestion of both ALA and its glycated forms generated peptide fractions, and intact undigested glycated ALA in the hydrolysates still covalently bound to d-galactose. High-resolution mass spectrometry revealed that a higher glycation degree was discovered in sonication-preprocessed ALA compared to native ALA. Enzyme-linked immunosorbent assay and basophil degranulation showed that sonication-assisted glycation could significantly reduce ALA allergenicity. The allergenicity of both gastric and gastroduodenal hydrolysates was further increased, and the hydrolysates of sonication-assisted glycated ALA showed the lowest allergenicity. The reason could be the shielding effect of the linear epitope found to be caused by a higher glycation degree; although linear epitopes were exposed, d-galactose covalently bound to intact undigested glycated ALA in the hydrolysates retained its masking role. These results indicated that sonication-assisted glycation could be a promising method to prepare immunotherapeutic agents for allergen immunotherapy to achieve the purpose of allergy desensitization.

Ultrasound assisted vis-à-vis classical heating for the conjugation of whey protein isolate-gellan gum: Process optimization, structural characterization and physico-functional evaluation

In the present work, ultrasonic assisted synthesis and characterization of Maillard conjugates of whey protein isolate (WPI) and gellan gum (GG) was carried out and compared with the classical heating method. Conjugation was confirmed by FTIR, secondary structure, intrinsic fluorescence analysis, and degree of glycation (DG). The structural analysis revealed high protein unfolding by sonication confirming loss of α-helix content and exposing more amino groups to the conjugation reaction. Color change analysis confirmed that ultrasonication accelerated the initial stage of Maillard reaction but did not form the advanced Maillard reaction products. Ultrasonication gave higher DG in lesser time (17.22% in 60 min) than classical heating method (8.41% in 4 h). Physico-functional properties such as pH and thermal stability, emulsifying activity index, emulsion stability index, foaming capability and antioxidant activity of WPI-GG conjugates prepared by ultrasonic treatment were superior to classical heating method suggesting ultrasonication as a potentially alternative method for Maillard conjugation. Industrial relevanceImprovising supplementary protein functionality by conjugation with food grade polysaccharides like gellan gum through ultrasonication could make the process more controllable and economical. The undesired browning can be inhibited in ultrasonic assisted conjugate synthesis and hence the overall acceptance of the final product can be increased.

Stability and bioaccessibility of curcumin emulsions stabilized by casein hydrolysates after maleic anhydride acylation and pullulan glycation

The effects of maleic anhydride (MA) acylation and pullulan glycation on casein hydrolysates (CH) and the physicochemical stability of modified or unmodified CH-stabilized emulsions were explored. Compared with casein, the solubility of CH was improved, and CH1 (hydrolysis degree 4%) exhibited the optimal emulsifying properties. After the acylation of MA, degrees of acylation (DA) increased with increasing addition of MA. Fourier-transform infrared spectroscopy revealed that a covalent bond was formed between MA and CH1. The results of pullulan glycation indicated that the degree of glycation decreased with increasing DA. Acylation combined with glycation effectively reduced the surface hydrophobicity of CH. Results of analysis of physicochemical stability and gastrointestinal fate of curcumin in emulsions revealed that CH modified by MA acylation and pullulan glycation played a positive role in enhancing the stability and bioaccessibility of curcumin loaded in emulsions.

Utilization of Maillard reaction in moist-dry-heating system to enhance physicochemical and antioxidative properties of dried whole longan fruit

This research aimed to enhance the physicochemical and antioxidant properties of dried whole longan fruit using Maillard reaction or non-enzymatic glycosylation (glycation) in a moist-dry-heating system at 60 °C with approximately 75% relative humidity for 5–50 days. During Maillard reaction, the browning index (BI) of the fruits increased significantly while lightless, redness and yellowness decreased. Interestingly, the rare sugars especially D-psicose and D-allose gradually increased by 2–3 folds when compared to the initial Maillard reaction. The development of D-mannose was additionally established through the glycation. The degree of glycation increased with the decrease of free amino acid, suggesting that conjugation of sugar with amino acids was involved. SDS-PAGE confirmed that the high molecular weight (HMW) of conjugated sugar-amino acid was the Maillard reaction product. The antioxidative properties including DPPH and ABTS radical scavenging activities, also ferric reducing antioxidant power (FRAP) were also increased as Maillard reaction progressed, which showed the activities in the range of 43.2–94.1 mg GAE/100 g dry basis, 0.23–3.09 g TE/100 g dry basis, and 0.35–5.95 g FeSO4/100 g dry basis, respectively. This study demonstrated a practical approach of Maillard reaction for the development of dried longan fruit with high antioxidative properties.

An insight into heat-induced gelation of whey protein isolate–lactose mixed and conjugate solutions: rheological behavior, microstructure, and molecular forces

It is known that protein/sugar conjugates prepared by Maillard reaction (MR) have good gel properties. However, there is not much information about the mechanism of MR on the gel properties of whey protein isolate (WPI). Electrophoresis confirmed the maximum molecular weight conjugate was obtained at incubation for 2 days, and its glycation degree was 82% by O-phthaldialdehyde (OPA) method. At this time, its absorbance at 294 nm and 420 nm increased significantly. The rheological results showed that the conjugate gel had better relative viscoelasticity, higher fracture modulus and mechanical strength, more covalent bonds in the gel structure and higher viscosity at high shear rates than the mixed gel. The total free sulfhydryl groups and relative fluorescence intensity of WPI–Lactose conjugate decreased significantly, indicating the conformation of WPI was altered after MR. Besides WPI–Lactose conjugate gel had a denser and smaller smooth pores microstructure by microcopy analysis.

Improved Heat Stability of Whey Protein Isolate by Glycation with Inulin

Glycation between proteins and sugars via the Maillard reaction has been shown to improve the heat stability of proteins. In this study, inulin, a healthy dietary fiber, was glycated with whey protein isolate (WPI), and the effects of reaction conditions were investigated. Conjugates were prepared by freeze-drying mixed WPI and inulin solutions at 1:1 to 6:1 WPI-to-inulin weight ratios followed by dry heating at 70, 75, or 80 °C for 12 to 72 h under uncontrolled, 44%, or 80% relative humidity. Heat stability was evaluated by turbidity, particle size, and rheological measurements. Degree of glycation was assessed by quantifying the loss of amino groups and the formation of the Amadori compounds. Results showed that conjugation led to improved heat stability, as shown by decreased turbidity and particle size as well as the ability to maintain the viscosity compared to control samples. Based on the loss of amino groups, the optimum glycation conditions were achieved with WPI–inulin mixtures at 2:1, 4:1, and 6:1 weight ratios and 80 °C temperature for 12 to 72 h without controlling the relative humidity. The improved heat stability could be due to an increase in negative charge as well as increased structural stabilization of the proteins. Under a limited degree of glycation, glycated WPI–inulin conjugates have great potential to be utilized as food ingredients, especially in the beverage industry.

Vitexin Inhibits Protein Glycation through Structural Protection, Methylglyoxal Trapping, and Alteration of Glycation Site.

In this study, the antiglycation potential and mechanisms of vitexin were explored in vitro by multispectroscopy, microscope imaging, high-resolution mass spectrometry, and computational simulations. Vitexin was found to show much stronger antiglycation effects than aminoguanidine. The inhibition against the fluorescent advanced glycation end products was more than 80% at 500 μM vitexin in both bovine serum albumin (BSA)-fructose and BSA-methylglyoxal (MGO) models. Treated with 100 and 200 μM vitexin for 24 h, the contents of MGO were reduced to 4.97 and 0.2%, respectively, and only one vitexin-mono-MGO adduct was formed. LC-Orbitrap-MS/MS analysis showed that vitexin altered the glycated sites and reduced the glycation degree of some sites. The mechanisms of vitexin against protein glycation were mainly through BSA structural protection, MGO trapping, and alteration of glycation sites induced by interaction with BSA. These findings provided valuable information about the functional development of vitexin as a potential antiglycation agent.

Modification of whey protein microgel particles with mono- oligo- and polysaccharides through the Maillard reaction: Effects on structural and techno-functional properties

Many food and drink products have a pH value between 4.0 and 6.0, which is near the isoelectric point (pI) of whey proteins. This study evaluated the modification of whey protein microgel (WPM) through Maillard conjugation with several common saccharides including arabinose, glucose, fructose, lactose, inulin, and maltodextrin in a liquid system, which is considered a potential route to boost the utilization of these protein particles in acidic conditions. Glycation degree (22–31 %), pH decrease, presence of final products, FTIR, and SDS-PAGE confirmed the bonding of carbohydrates to WPMs. The conjugates prepared by lactose, glucose, and inulin, i.e. moderately reactive carbohydrates, rendered lower surface hydrophobicity, higher colloidal stability (∼40−50% at pH 4.0), and improved emulsifying properties in comparison with WPM, heated WPM and other glycoproteins. Foaming capacity of Maillard reaction products was lower or without change relative to the WPM; however, foam prepared by maltodextrin-glycated WPM was substantially more stable (up to 24 h). These findings could open avenues for applicability of these pre-denatured densely-packed particles in a range of food products and soft-matter applications.