Biological activities and physicochemical properties of Maillard reaction products in sugar–bovine casein peptide model systems

Glycated Walnut Meal Peptide-Calcium Chelates: Preparation, Characterization, and Stability

Finding stable and bioavailable calcium supplements is crucial for addressing calcium deficiency. In this study, glycated peptide-calcium chelates (WMPHs-COS-Ca) were prepared from walnut meal protein hydrolysates (WMPHs) and chitosan oligosaccharides (COSs) through the Maillard reaction, and the structural properties and stability of the WMPHs-COS-Ca were characterized. The results showed that WMPHs and COSs exhibited high binding affinities, with a glycation degree of 64.82%. After glycation, Asp, Lys, and Arg decreased by 2.07%, 0.46%, and 1.06%, respectively, which indicated that these three amino acids are involved in the Maillard reaction. In addition, compared with the WMPHs, the emulsifying ability and emulsion stability of the WMPHs-COS increased by 10.16 mg2/g and 52.73 min, respectively, suggesting that WMPHs-COS have better processing characteristics. After chelation with calcium ions, the calcium chelation rate of peptides with molecular weights less than 1 kDa was the highest (64.88%), and the optimized preparation conditions were 5:1 w/w for WMPH-COS/CaCl2s, with a temperature of 50 °C, a chelation time of 50 min, and a pH of 7.0. Scanning electron microscopy showed that the "bridging role" of WMPHs-COS changed to a loose structure. UV-vis spectroscopy and Fourier transform infrared spectrometry results indicated that the amino nitrogen atoms, carboxyl oxygen atoms, and carbon oxygen atoms in WMPHs-COS chelated with calcium ions, forming WMPHs-COS-Ca. Moreover, WMPHs-COS-Ca was relatively stable at high temperatures and under acidic and alkaline environmental and digestion conditions in the gastrointestinal tract, indicating that WMPHs-COS-Ca have a greater degree of bioavailability.

Physicochemical characterization and environmental stability of a curcumin-loaded Pickering nanoemulsion using a pea protein isolate-dextran conjugate via the Maillard reaction

This study investigated pea protein isolate (PPI) and dextran (DX) conjugates produced via the Maillard reaction as Pickering stabilizers for various food applications. The results found that as heating time increased (0-5 h), the grafting degree heightened. The PPI-DX conjugate exhibited a rough porous surface in contrast to native PPI, accompanied by changes in molecular weight and secondary structure. Additionally, the aggregation of low-solubility PPI was partially inhibited due to the contribution of increased solubility and reduced surface hydrophobicity by glycation. Curcumin-loaded Pickering nanoemulsions stabilized with PPI-DX had smaller droplets and higher curcumin encapsulation (greater than80 %) than PPI-stabilized nanoemulsions. PPI-DX adsorbed on the interface showed improved physical stability compared to PPI alone, even after various pH conditions and three heat treatments. The nanoemulsion stabilized with PPI-DX demonstrated improved apparent viscosity and dispersion stability. These findings highlight the effectiveness of PPI-DX conjugates as stabilizers for developing stable and functional Pickering nanoemulsions.

Effect of enzymolysis combined with Maillard reaction treatment on functional and structural properties of gluten protein

In this work, the modified gluten was prepared by enzymolysis combined with Maillard reaction (MEG), and its functional and structural properties were investigated. The result showed that the maximum foamability of MEG was 19.58 m2/g, the foam stability was increased by 1.8 times compared with gluten, and the solubility and degree of graft were increased to 44.4 % and 28.1 % at 100 °C, whereas the content of sulfhydryl group decreased to 0.81 μmol/g. The scavenging ability on ABTS+radical and DPPH radical of MEG was positively correlated with reaction temperature, and the maximum values were 86.57 % and 71.71 % at 140 °C, respectively. Furthermore, the fluorescence quenching effect of tryptophan and tyrosine residues was enhanced, while the fluorescence intensity decreased with the temperature increase. Scanning electron microscopy revealed that the surface of enzymatically hydrolyzed-gluten became smooth and the cross section became straightened, while MEG turned smaller and irregular approaching a circular structure. FT-IR spectroscopy showed that enzymatic hydrolysis promoted the occurrence of more carbonyl ammonia reactions and the formation of precursors of advanced glycosylation end products. These results provide a feasible method for improving the structure and functional properties of gluten protein.

Development and evaluation of anti-reflux functional-oral suspension raft composed of sodium alginate-mung bean protein complex

This study aimed to develop a sodium alginate (Na alginate) and mung bean protein (MBP) raft complex to improve gastric reflux symptoms. Na alginate and MBP complexes with different ratios (1:1, 2:1, and 3:1, respectively) were used for raft formulations through a wet Maillard reaction. Structural properties of raft strength, reflux resistance, intrinsic fluorescence emission spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were investigated for rafts. The suspension 1:1 Na alginate/MBP with 0 h Maillard reaction time exhibited the lowest sedimentation volume among the suspensions. In contrast, 3:1 Na alginate/MBP with 6 h Maillard reaction time showed the highest sedimentation volume. Based on the results, the 3:1 Na alginate/MBP rafts had the best results, and the results were within acceptable limits. Functional properties, including antioxidant properties, the Helicobacter pylori inhibition assay, the pancreatic lipase inhibition assay, and angiotensin-converting enzyme (ACE) inhibition, were investigated for rafts. The Na alginate/MBP raft has similar characteristics to Gaviscon syrup and can be used for obesity, Helicobacter pylori infection, high blood pressure, and gastric reflux.

Characteristics and antioxidant properties of Harpadon nehereus protein hydrolysate-xylose conjugates obtained from the Maillard reaction by ultrasound-assisted wet heating in a natural deep eutectic solvents system

BACKGROUND

Harpadon nehereus is a high-protein marine fish. A valuable way to add value to H. nehereus is to convert it into protein hydrolysate. The Maillard reaction is an effective way to improve the functional properties of peptides and proteins, which are affected by many factors such as reactant concentration, water activity, pH, temperature, and heating time. However, the traditional Maillard reaction method is inefficient. The purpose of this study was therefore to explore the effect of the ultrasound-assisted wet heating method on the Maillard reaction of H. nehereus protein hydrolysate (HNPH) in a new-type green solvent - a natural hypereutectic solvent (NADES).

RESULTS

Harpadon nehereus protein hydrolysate-xylose (Xy) conjugates were prepared via a Maillard reaction in a NADES system using an ultrasound-assisted wet heating method. The effects of different treatment conditions on the Maillard reaction were studied. The optimized glycation degree (DG) of HNPH-Xy conjugates was obtained with a water content of 10%, a reaction temperature of 80 °C, a reaction time of 35 min, and an ultrasonic power level of 300 W. Compared with HNPH, the structure of HNPH-Xy conjugates were significantly changed. Moreover, the functional properties and antioxidant activity of HNPH-Xy were all superior to the HNPH.

CONCLUSIONS

An ultrasound-assisted wet-heating Maillard reaction between HNPH and Xy in the NADES system could be a promising way to improve the functional properties of HNPH. © 2023 Society of Chemical Industry.

Bovine Bone Gelatin-Derived Peptides: Food Processing Characteristics and Evaluation of Antihypertensive and Antihyperlipidemic Activities

This study aimed to evaluate the food processing properties of bovine bone gelatin-derived peptides (BGPs) and their effects and mechanisms on hypertension and hypertension complications in spontaneously hypertensive rats (SHRs). BGPs had good acid, high temperature, and NaCl resistance abilities in vitro. Additionally, Maillard reaction of BGPs with low-dose reducing sugar (≤15%) exhibited a free radical scavenging effect. BGPs significantly reduced the blood pressure, triglyceride levels, and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in SHRs through downregulated angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II type 1 receptor (AT1R) levels and the upregulated Ang II type 2 receptor (AT2R) level. In brief, BGP could alleviate hypertension and dyslipidemia in SHRs by inhibiting ACE/Ang II/AT1R and activating the Ang II/AT2R signaling pathway. Our study suggests that BGP has good food processing properties and could be a potential nutraceutical for antihypertensive and antihyperlipidemic issues.

Comprehensive characterization of the bacterial community structure and metabolite composition of food waste fermentation products via microbiome and metabolome analyses

Few studies have characterized the microbial community and metabolite profile of solid food waste fermented products from centralized treatment facilities, which could potentially be processed into safe animal feeds. In this study, 16S rRNA gene sequencing and liquid/gas chromatography-mass spectrometry were conducted to investigate the bacterial community structure and metabolite profile of food waste samples inoculated with or without 0.18% of a commercial bacterial agent consisting of multiple unknown strains and 2% of a laboratory-made bacterial agent consisting of Enterococcus faecalis, Bacillus subtilis and Candida utilis. Our findings indicated that microbial inoculation increased the crude protein content of food waste while reducing the pH value, increasing lactic acid production, and enhancing aerobic stability. Microbial inoculation affected the community richness, community diversity, and the microbiota structure (the genera with abundances above 1.5% in the fermentation products included Lactobacillus (82.28%) and Leuconostoc (1.88%) in the uninoculated group, Lactobacillus (91.85%) and Acetobacter (2.01%) in the group inoculated with commercial bacterial agents, and Lactobacillus (37.11%) and Enterococcus (53.81%) in the group inoculated with homemade laboratory agents). Microbial inoculation reduced the abundance of potentially pathogenic bacteria. In the metabolome, a total of 929 substances were detected, 853 by LC-MS and 76 by GC-MS. Our results indicated that inoculation increased the abundance of many beneficial metabolites and aroma-conferring substances but also increased the abundance of undesirable odors and some harmful compounds such as phenol. Correlation analyses suggested that Leuconostoc, Lactococcus, and Weissella would be promising candidates to improve the quality of fermentation products. Taken together, these results indicated that inoculation could improve food waste quality to some extent; however, additional studies are required to optimize the selection of inoculation agents.

Kiwicha (Amaranthus caudatus L.) protein hydrolysates reduce intestinal inflammation by modulating the NLRP3 inflammasome pathway

Amaranthus caudatus hydrolysates are investigated as a valuable source of active peptides able to take part as functional ingredients in food and nutraceutical preparations to prevent intestinal inflammation.

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.

Molecular characterization of sequence-driven peptide glycation

Peptide glycation is an important, yet poorly understood reaction not only found in food but also in biological systems. The enormous heterogeneity of peptides and the complexity of glycation reactions impeded large-scale analysis of peptide derived glycation products and to understand both the contributing factors and how this affects the biological activity of peptides. Analyzing time-resolved Amadori product formation, we here explored site-specific glycation for 264 peptides. Intensity profiling together with in-depth computational sequence deconvolution resolved differences in peptide glycation based on microheterogeneity and revealed particularly reactive peptide collectives. These peptides feature potentially important sequence patterns that appear in several established bio- and sensory-active peptides from independent sources, which suggests that our approach serves system-wide applicability. We generated a pattern peptide map and propose that in peptide glycation the herein identified molecular checkpoints can be used as indication of sequence reactivity.

Effects of glycation and acylation on the structural characteristics and physicochemical properties of soy protein isolate

This study examined the effects of different sequential treatments of dextran glycation and succinic anhydride acylation on the structure and physicochemical properties of soy protein isolate (SPI). The tested properties included electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy, endogenous fluorescence spectroscopy, surface hydrophobicity (H₀ ), free sulfhydryl (-SH), solubility, interfacial properties, rheological properties, and scanning electron microscope (SEM). The results show that the two treatments significantly improved the structure and functional characteristics of the SPI. The order of the methods had an important effect on the SPI. The lowest H₀ (231.76 ± 11.92), the highest free -SH content (3.09 ± 0.09 µmol/g), and the highest solubility at pH = 7 (77 ± 3.97%) were obtained when the acylation treatment was followed by the glycation treatment. Emulsification, emulsion stability, foaming, and foam stability were also the highest. Glycation and acylation caused the viscosity coefficient (k) of the SPI solution to decrease compared with SPI alone, but the flow index (n) value increased, and the sum G' value of the conjugate system decreased as gel time increased. SEM showed that its microstructure has changed significantly. Therefore, this research provided an effective method for improving the functional characteristics of SPI and had potential industrial application prospects. PRACTICAL APPLICATION: Glycation and acylation of soybean protein isolate improved the chemical modification method of protein, improved the functional properties of soybean protein, widened its application in food and materials, and provided a new idea for the further development and utilization of soybean protein.

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.

Impact of heat treatment on anti-oxidative and anti-colon cancer activities of the soluble extracts from black mulberry (Morus nigra L.) using water and ethanol-water solvents

Black mulberry (Morus nigra L.) is an edible fruit with various health functions in the body. In this study, the lyophilized black mulberry was extracted using water and 75% (v/v) ethanol-water, respectively; afterwards, the soluble extracts were subjected to these treatments like ethanol removal, heat treatment at 100 °C for various times, or activated carbon-mediated dephenolization. The assaying results indicated that the used heat treatment led to decreased anthocyanin but increased total phenol and flavonoid contents for the water- and ethanol-extracts, while the dephenolized extracts after the heat treatment also had increased total phenol and flavonoid contents. The performed heat treatment decreased anti-oxidative activities of the water- and ethanol-extracts, resulting in reduced scavenging activities to the DPPH and hydroxyl radicals and lower reducing power for Fe(iii) ions. However, the results from cell experiments also demonstrated that the heat treatment at 100 °C for 45 min caused the water- and ethanol-extracts or dephenolized extracts with higher anti-cancer activity against human colon cancer HCT-116 cells. Overall, the heated extracts were more effective than the unheated counterparts to inhibit cell growth, alter cell morphology, generate more intracellular reactive oxygen species, enhance intracellular Ca2+ level, and reduce mitochondrial membrane potential of the cells. It is thereby concluded that the heat treatment of black mulberry might reduce its anti-oxidation but increase its anti-colon cancer effect due to the occurrence of the Maillard reaction and other unidentified reactions, which will deepen our present knowledge and provide a scientific basis to optimize storage or processing conditions of plant-based foods.

Process optimization and the relationship between the reaction degree and the antioxidant activity of Maillard reaction products of chicken liver protein hydrolysates

The aim of this study was to optimize the protein hydrolysates from chicken liver with xylose under Maillard reaction (MR) conditions using response surface methodology. The correlation between the browning degree, grafting degree, and the antioxidant activities of the Maillard reaction products (MRPs) was investigated. The optimal reaction conditions were achieved with a reaction temperature of 138.78°C, an initial pH of 7.99, and a reaction time of 93.14 min. The grafting degree (41.98%) and browning degree (2.582) of chicken liver protein hydrolysate MRPs (CLPHM) were notably higher (P < 0.05) than those of protein MRPs (CLPM) and were significantly lower (P < 0.05) than those of sonicated hydrolysate MRPs (SCLPHM). The reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and hydroxyl radical scavenging of CLPM, CLPHM, and SCLPHM were significantly higher (P < 0.01) than those of the protein or hydrolysate substrates. The grafting degree and browning degree of CLPM, CLPHM, and SCLPHM had positive correlations with DPPH and hydroxyl radical scavenging activity. Hence, this study could enhance the added value of chicken liver by exhibiting the enhancements from ultrasound pretreatment and the MR. MRPs could have an effective and potential application in the food industry.

Formation and Antioxidant Activity of Maillard Reaction Products Derived from Different Sugar-amino Acid Aqueous Model Systems of Sesame Roasting

This investigation was carried out to offer insight into the formation and antioxidant activity of Maillard reaction products (MRPs) derived from various sugar-amino acid model systems active in the roasting of sesame seeds. Reducing sugars (glucose, fructose, and xylose) and amino acids (serine, cystine, arginine, and lysine) present in sesame seeds were used to prepare the MRPs at various reaction times, and then the effect of reaction time on the MRPs derived from the various model systems was investigated. Within the first 15 min, the amounts of free amino groups decreased around 40% remaining amino groups of Lys-sugar model and around 75% remaining amino groups of Arg-sugar model. Results indicated that reducing sugar and free amino groups decreased obviously in Lys- and Arg-model systems. Based on correlation coefficient of antioxidant activities assessment and MRP formation in the Lys- and Arg-model systems above 0.978 and an extremely significant correlation in Pearson test exists, a conclusion could be made that these model systems are critical contributing factors in MRP formation during the roasting of sesame seeds. These findings offer insight into the formation and antioxidation of MRPs during the sesame seeds roasting.

Fabricating a Pickering Stabilizer from Okara Dietary Fibre Particulates by Conjugating with Soy Protein Isolate via Maillard Reaction

Okara is underutilized despite its numerous values explorable in food products. In this study, okara dietary fibre (ODF) was micronized and decorated with soy protein isolate (SPI) through a Maillard reaction by dry heating at 60 °C. The resulting ODF-SPI conjugates were thermally stable, hydrophilic rather than hydrophobic, and exhibited excellent Pickering emulsion stabilization potentials as indicated in their interfacial behaviour, microstructure, droplet sizes, emulsifying activity index (EAI) and emulsion stability index (ESI). In addition, the conjugates' structure-function relationships, amino acid profile, and emulsifying potentials are indicative of being employed in the formulation of emulsion-based foods or non-edible products.

Formation of Nϵ-Carboxymethyllysine and Nϵ-Carboxyethyllysine in Prepared Chicken Breast by Pan Frying

The objective of this work was to investigate the effects of pan frying on the formation of two typical advanced glycation end products (AGEs) named N^ϵ-carboxymethyllysine (CML) and N^ϵ-carboxyethyllysine (CEL) in prepared chicken breast. The marinated chicken breast was pan fried for 1 to 6 min, and then protein, fat, moisture, carbonyl, sulfhydryl, thiobarbituric acid reactive substances, chroma (a*, b*, L*), absorbance at 294 and 420 nm, and AGE (CEL) levels were measured once a minute. Pearson's correlation was determined and indicated that moisture was significantly negatively correlated with Maillard reaction and AGEs (P < 0.05), fat and protein contents were significantly positively correlated with AGEs (P < 0.05), and a* values were positively correlated with Maillard reaction and CEL (P < 0.05). Protein and lipid oxidation played an important role on the correlation of AGEs. In conclusion, Maillard reaction and oxidation reaction are two important factors affecting AGE formation.

Maillard reaction products derived from food protein-derived peptides: insights into flavor and bioactivity

Food protein-derived peptides serve as food ingredients that can influence flavor and bioactivity of foods. The Maillard reaction plays a crucial role in food processing and storage, and generates a wide range of Maillard reaction products (MRPs) that contribute to flavor and bioactivity of foods. Even though the reactions between proteins and carbohydrates have been extensively investigated, the modifications of food protein-derived peptides and the subsequent impacts on flavor and bioactivity of foods have not been fully elucidated. In this review, the flavor and bioactive properties of food-derived peptides are reviewed. The formation mechanisms with respect to MRPs generated from food protein-derived peptides have been discussed. The state-of-the-art studies on impacts of the Maillard reaction on flavor and bioactivity of food protein-derived peptides are also discussed. In addition, some potential negative effects of MRPs are described.

Maillard reaction derived from oil-tea camellia seed through roasting

BACKGROUND

The Maillard reaction products (MRPs) formed after roasting of oil-tea camellia seeds (camellia seeds) were investigated. Camellia seeds are inevitably heated during processing, but the effect of heating or roasting on the physicochemical properties of camellia seed or oil-tea camellia seed oil (camellia oil) has been seldom studied, especially with respect to the Maillard reaction.

RESULTS

Changes in reducing sugars, free amino acids, pH, color, browning intensity and MRP (furosine, glyoxal, methylglyoxal, 5-hydroxymethylfurfural and furural) concentrations were examined in camellia seeds during roasting at 120-160 °C for 20-120 min. Results showed that roasting leads first to a decrease and then to a considerable increase in free amino groups and, at the same time, to a reduction in moisture content and decrease in pH. The sucrose content of the seeds decreased, while that of glucose and fructose increased reciprocally during roasting. On the other hand, the observed changes concerning glyoxal were negligible. Furthermore, 5-hydroxymethylfurfural and furfural have been found at the end of the roasting process, with maximum values of 572.26 ± 1.91 mg kg^-1 dry wt and 0.46 ± 0.003 mg kg^-1 dry wt, at 160 °C for 120 min, respectively.

CONCLUSION

This investigation provides the initial groundwork necessary for the development and implementation of green and efficient technology that could be applied to obtain high-quality camellia oil. Future research is necessary to assess antioxidant capacity, quality and safety of oil after thermal processing of camellia seeds. © 2019 Society of Chemical Industry.

Comparative study on the Maillard reaction of chitosan oligosaccharide and glucose with soybean protein isolate

Chitosan oligosaccharide (COS) has multiple biological properties and is hence promising in the modification of proteins through Mallard reaction. Its susceptibility to the reaction with soybean protein isolate (SPI) was evaluated by comparing with glucose (Glu). Conjugation with COS led to milder color change, less furosine and hydroxymethyl furfural formation, and fewer lysine/arginine consumption than with Glu, implying that COS was less susceptible to the Maillard reaction with SPI than Glu. Intrinsic fluorescence analysis indicated that different intermediate products were generated in the SPI-Glu and SPI-COS conjugates and the former intermediates were more prone to condensation to brown pigments. SDS-PAGE illustrated that COS inclined to conjugate with the small subunits of SPI. Conjugation with COS caused SPI unfolding and improved its emulsifying activity. Hence, COS has great potential in the modification of proteins through Maillard reaction and other attributes of the resultant conjugates, such as antioxidant and antibacterial activities, deserve further study.

Inhibition of Maillard Reactions by Replacing Galactose with Galacto-Oligosaccharides in Casein Model Systems

Lactose reduced dairy products are more prone to Maillard reactions due to the presence of reactive monosaccharides. Conventional β-galactosidases, which are used for lactose hydrolysis in lactose-reduced dairy products, will lead to conversion of lactose into glucose and galactose, where especially galactose is very reactive during Maillard reactions. Some β-galactosidases have transgalactosylating activity and will thus convert lactose into galacto-oligosaccharides (GOS) and hereby limit the release of galactose. The aim of this study was to investigate the extent of participation of GOS in Maillard reactions in comparison to lactose, a 50:50 mixture of glucose and galactose, and galactose exclusively in sodium caseinate-based milk-like model systems heated at 130 and 75 °C at pH 6.8. The GOS system exhibited reduced loss of free amino groups; accumulated less furosine and less of the following advanced glycation end products (AGEs): N^ε-carboxyethyl lysine, methylglyoxal-derived hydroimidazolone isomers, glyoxal-derived lysine dimer, and methylglyoxal-derived lysine dimer; and also developed less browning compared to monosaccharide models. However, the GOS-caseinate system accumulated more 3-deoxyglucosone and 3-deoxygalactosone, which resulted in higher concentrations of 5-(hydroxymethyl)furfural and pyrraline. The results indicated that GOS overall participate less readily in Maillard reactions than the monosaccharides investigated but were more prone to degradation to C6 α-dicarbonyls species. Finally, relationship analysis indicated that C6 α-dicarbonyls seemed to primarily increase concentrations of 5-(hydroxymethyl)furfural instead of AGEs. Our results suggest that conversion of lactose into GOS instead of monosaccharides in milk by transgalactosylating β-galactosidases could be a useful strategy for production of lactose-free milk for people with lactose intolerance.

Tracking the behavior of Maillard browning in lysine/arginine-sugar model systems under high hydrostatic pressure

BACKGROUND

High-pressure processing is gaining popularity in the food industry. However, its effect on the Maillard reaction during high-pressure-assisted pasteurization and sterilization is not well documented. This study aimed to investigate the effects of high hydrostatic pressure on the Maillard reaction during these processes using amino acid (lysine or arginine)-sugar (glucose or fructose) solution models.

RESULTS

High pressure retarded the intermediate and final stages of the Maillard reaction in the lysine-sugar model. For the lysine-glucose model, the degradation rate of Amadori compounds was decelerated, while acceleration was observed in the arginine-sugar model. Increased temperature not only accelerated the Maillard reaction over time but also formed fluorescent compounds with different emission wavelengths. Lysine reacted with the sugars more readily than arginine under the same conditions. In addition, it was easier for lysine to react with glucose, whereas arginine reacted more readily with fructose under high pressure.

CONCLUSION

High pressure exerts different effects on lysine-sugar and arginine-sugar models. © 2017 Society of Chemical Industry.

Antimicrobial and antioxidant capacity of glucosamine-zinc(II) complex via non-enzymatic browning reaction

Coordination compounds play an important role in the life process, and have been widely used in food, cosmetics and pharmaceutical industry. Herein, we have developed a novel kind of glucosamine-zinc(II) complex (GlcN-ZC) for food additive using non-enzymatic browning reaction. The GlcN-ZC was characterized by FTIR and XRD. Moreover, UV absorbance changes, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of GlcN-ZC were also evaluated. Results showed the GlcN-ZC intermediate compounds were accumulated in non-enzymatic browning while prolonging heating time and melanoidins were produced in the final stage. The fluorescence changes confirmed that fluorophores were formed during the non-enzymatic reaction and fluorescence intensity reached a maximun at 60 min. The highest radical scavenging activity of GlcN-ZC formed after 180 min of heating was 79.2%. Furthermore, GlcN-ZC exhibited excellent antibacterial activity against E. coli and S. aureus. Therefore, GlcN-ZC can be used as a novel promising additive in the food industry.

Using an enzymatic galactose assay to detect lactose glycation extents of two proteins caseinate and soybean protein isolate via the Maillard reaction

BACKGROUND

Glycation of food proteins via the Maillard reaction has been widely studied in the recent years; however, the amount of saccharide connected to proteins is usually not determined. An enzymatic galactose assay was proposed firstly in this study to detect lactose glycation extents of caseinate and soybean protein isolate (SPI) during the Maillard reaction at two temperatures and different times.

RESULTS

The separated glycated proteins were hydrolysed to release galactose necessary for the enzymatic assay and glycation calculation. Caseinate and SPI both obtained the highest lactose glycation extents at 100 °C or 121 °C by a reaction time of 180 or 20 min. Short- and long-time reaction resulted in lower glycation extents. During the reaction, three chemical indices (absorbences at 294/490 nm and fluorescence intensities) of reaction mixtures increased continually, but another index reactable NH₂ of glycated proteins showed the opposite trend. In general, changing profiles of the four indices were inconsistent with those profiles of lactose glycation extents of glycated proteins, implying practical limitation of the four indices in studies.

CONCLUSION

This proposed enzymatic assay could directly detect lactose glycation of the two proteins, and thus was more useful than the four chemical indices to monitor glycation of the two proteins. © 2016 Society of Chemical Industry.

New functionalities of Maillard reaction products as emulsifiers and encapsulating agents, and the processing parameters: a brief review

Non-enzymatic browning has been a wide and interesting research area in the food industry, ranging from the complexity of the reaction to its applications in the food industry as well as its ever-debatable health effects. This review provides a new perspective to the Maillard reaction apart from its ubiquitous function in enhancing food flavour, taste and appearance. It focuses on the recent application of Maillard reaction products as an inexpensive and excellent source of emulsifiers as well as superior encapsulating matrices for the entrapment of bioactive compounds. Additionally, it will also discuss the latest approaches employed to perform the Maillard reaction as well as several important reaction parameters that need to be taken into consideration when conducting the Maillard reaction. © 2016 Society of Chemical Industry.