Search

This research elucidated the reason of flavor deficiency during the thermal degradation of glutamic acid (Glu)-galactose (Gal) Amadori rearrangement product (GG-ARP) and the solution. The flavor formation from GG-ARP during the thermal degradation was investigated. Compared to the volatile compounds in Glu-Gal Maillard reaction products (GG-MRP), pyrazines in the volatile compounds derived from GG-ARP were restrained. The disadvantage in evolution asynchrony and content sufficiency of α -dicarbonyl compounds and Glu in the GG-ARP model limited the pyrazines formation. With the addition of Gal, the asynchronous effect was further exacerbated, and the furans in the GG-ARP-Gal model (956.81 μg/L, 120 °C, 60 min) were more significantly dominant among the volatile flavor compounds than in the GG-ARP model (454.98 μg/L, 120 °C, 60 min), while the pyrazines were still missing. Whereas, the extra-added Glu in the GG-ARP model could offset the deficiency of amino acids growth after α -dicarbonyl formation and promote the formation of pyrazines (74.47 μg/L, 120 °C, 60 min). Meanwhile, the formation of diketones (92.96 μg/L, 120 °C, 60 min) was promoted. The addition of Glu enhanced both milk-like and baking flavor of the GG-ARP system simultaneously. Formulated GG-ARP-Glu mixture was proposed to promisingly achieve the controlled formation of process flavors for baked foods with both desirable milk-like and baking scent. [Display omitted] • Evolution of dicarbonyls and glutamic acid was asynchronous during ARP degradation. • Asynchronous effect was further exacerbated with the exogenous galactose addition. • Exogenous glutamic acid promoted the formation of both pyrazines and diketones. [ABSTRACT FROM AUTHOR]

This research involved the formation of volatile flavor compounds due to the combined effect of enzymatically hydrolyzed milk fat and glutamic acid-galactose Amadori rearrangement product (Glu-Gal-ARP). A novel formulated frankincense-like flavor precursors produced by a specific ARP and enzymatically hydrolyzed milk fat was proposed. The relative molecular weight of Glu-Gal-ARP was 309, and the molecular formula was C11H19NO9 determined through LC–MS and NMR analysis. The enzymatically hydrolyzed milk fats were prepared with different degrees of hydrolysis and mixed with the glutamic acid-galactose ARP as frankincense-like flavor precursors. The flavor compounds formed from the precursors during thermal treatment were analyzed by GC–MS, sensory evaluation, and partial least squares regression analysis (PLSR). An optimal flavor profile was obtained when the enzymatically hydrolyzed milk fats with an acid value of 3.897 mg/g, peroxide value of 0.257 mmol/kg, and carbonyl value of 11.417 mL/g were used, and the thermal processing products were obtained by heating at 120 °C for 60 min. A total of 33 aroma compounds were observed as the characteristic frankincense-like flavor compounds through the correlation between the volatile compounds and sensory characteristics of the thermal reaction products by PLSR, therein, 14 compounds were from ARP, 7 compounds were from the enzymatically hydrolyzed milk fats, and 8 compounds were from the interaction of ARP and enzymatically hydrolyzed milk fats. The frankincense-like flavor precursor has the potential to be used as the flavor enhancer in the processing of frankincense-like foods. [ABSTRACT FROM AUTHOR]

As an electrostatic deposited coating for gelatin/sodium carboxymethyl cellulose (CMC) coacervates, chitosan was applied to improve their stability and resistance against harsh environment (extreme pH, high ionic strength and high temperature). With eugenol as the core material, gelatin/CMC microcapsules (SM) and gelatin/CMC microcapsules coated by chitosan (DM) were prepared, and their structures were further characterized. To minimize the bridging flocculation of chitosan by the electrostatic interaction, SM were prepared at pH 4.4 and coated by chitosan at pH 5.0. According to the thermal gravimetric analysis results, the degradation temperature of DM was 292 °C compared to 265 °C of SM. The eugenol retention of SM decreased from 65% to 20% as pH increased from 2 to 10, while DM always kept it over 70% between pH 2–10. Moreover, the eugenol retention of DM remained at 70%–80% with an ionic strength of 0–200 mmol/L (pH 4 and 10). CLSM and SEM confirmed that the SM were coated with chitosan, and the Fourier transform infrared (FTIR) spectra showed that electrostatic force played a main role in the binding of gelatin, CMC and chitosan. Circular dichroism (CD) revealed that the secondary structure of gelatin molecules was changed from a flexible pattern to an ordered pattern due to the addition of CMC and chitosan. Consequently, the chitosan coating could improve the stability of complex coacervated microcapsules in harsh environments, which might have a broad prospect to protect essential oils and flavor substances against severe harsh environmental stresses during in the processing of food and pharmaceuticals. [Display omitted] ● Chitosan significantly reduced the environmental sensitivity of Gelatin/CMC. ● Dominant force among gelatin, CMC and chitosan was electrostatic interaction. ● Addition of CMC and chitosan made gelatin structure tend to be ordered. [ABSTRACT FROM AUTHOR]

• Added glycine boosts the diversity of furans via formaldehyde in chain elongation. • Added glutamic acid or lysine promote pyrazine formation by nucleophilic attack. • Glyoxal promoted the degradation of ARP and retro-aldol cleavage of deoxyosone. The role of amino acids and α-dicarbonyls in the flavor formation of Amadori rearrangement product (ARP) during thermal processing was investigated. Comparisons of the volatile compounds and their concentrations when N -(1-deoxy-α- d -ribulos-1-yl)-glycine reacted with different amino acids or glyoxal (GO) at 100 °C were executed. Additional amino acids, such as glycine (Gly), in ARP models contributed to the diversity of furanoids by the chain elongation of the derived formaldehyde. Whereas the monoanion of additional glutamic acid acted as nucleophile, favored 2-ethyl-3,5-dimethylpyrazine and 2,5-dimethylpyrazine formation; the nonionized amino group of additional lysine were involved in α-dicarbonyls formation, causing pyrazine and methylpyrazine accumulation in the ARP model. Moreover, the high dosage and pH stabilization of additional GO probably promoted the ARP degradation and deoxyosones retro-aldol cleavage, resulting in methylpyrazine rather than furanoids formation. The present work provided the guidance for the controlled flavor formation of ARP in industrial application. [ABSTRACT FROM AUTHOR]

The complex composition of braised pork, including lean meat, pigskin, and fat, makes it difficult for sensory evaluation of its texture properties. This study investigated the correlation between sensory texture attributes and physicochemical properties to achieve an objective and comprehensive evaluation of the texture of braised pork. Sensory analysis demonstrated that the overall texture acceptability of braised pork was significantly and negatively influenced by sensory texture attributes (including sensory hardness, chewiness, and toughness), while it was positively impacted by sensory adhesiveness, softness, and juiciness. Shear force and texture profile analysis (TPA) variables, reflecting mastication behavior, were used to characterize the textural properties of braised pork. They were closely related to water distribution, with a higher proportion of immobilized water (P21), indicating a higher water holding capacity and a more tender texture. Correlation analysis between sensory texture attributes and physicochemical properties through partial least squares regression further revealed significant associations between shear force, TPA variables, and sensory texture attributes. Moreover, the proportion of immobilized water (P21) significantly and negatively affected sensory hardness and chewiness, whereas the proportion of free water (P22) significantly influenced sensory toughness. Sensory texture attributes could be well predicted by the physicochemical properties by projecting test samples onto calibration models established by known samples. Therefore, a combination of sensory and instrumental measures can reliably reflect the texture properties of braised pork. Practical Application: The combination of sensory and instrumental methods is an effective strategy to accurately and objectively evaluate the texture properties of braised pork, which overcomes the limitations caused by the complexity of the composition and texture traits of braised pork. The accurate evaluation and standardization of texture properties is an important premise for the repeatable and stable cooking of traditional braised pork. Furthermore, this research method and findings can also be applied to guide the procedural optimization of smart appliances (e.g., induction cookers) for cooking braised pork. [ABSTRACT FROM AUTHOR]

The current study was devoted to preparing biopolymer nanoparticles stable to harsh environment (extreme pH, high ionic strength and high temperature) to improve the protection of cinnamaldehyde. Cinnamaldehyde-loaded nanoparticles (NPs-C) were prepared by heating electrostatic complexes of whey protein isolate-dextran conjugate (WPI-Dex) and chondroitin sulfate (ChS) in the presence of cinnamaldehyde. Results showed relatively high encapsulation efficiency and loading capacity (76.57% and 19.02% respectively). The particle size was around 185 nm and the polydispersity index (PDI) was 0.22. Both hydrogen bonding and hydrophobic interactions facilitated the successful entrapment of cinnamaldehyde into the nanoparticles. The NPs-C were stable over the pH range of 1–10 in the absence or presence of various NaCl concentrations (1–4 M). Moreover, the nanoparticles remained stable against a combined effect of different pH, different ionic strength and heating (90 °C, 30 min). Interestingly, the result indicated that the addition of NaCl improved the heat stability of NPs-C especially at pH 2. Results have also revealed that cinnamaldehyde encapsulation has improved its storage stability, where nanoparticles have effectively protected cinnamaldehyde during storage for 6 weeks both at 4 °C and 25 °C. The WPI-Dex/ChS nanoparticles fabricated in this research have a promising prospect to protect essential oils or bioactive compounds against harsh environmental stresses in food, nutraceutical and pharmaceutical industries. Furthermore, the sustained antimicrobial activity endows NPs-C with a great potential application in the aforementioned industries. Image 1 • Cinnamaldehyde-loaded nanoparticles were obtained by heat-induced gelation method. • Combined effect of pH, ionic strength and heat on stability was studied. • Biopolymer nanoparticles were stable against harsh environment. • NaCl addition was able to improve the stability of nanoparticles. [ABSTRACT FROM AUTHOR]

• Metal complexed-enzymatic hydrolyzing prepared chitosan of narrower M W distribution. • Chitosan with M W of 5.67 kDa could hold moisture and retain a lower a W. • Mounting newly formed chain-end hydrophilic groups increased moisture retention. To obtain chitosan (CTS) with narrower molecular weight distribution, CTS with weight-average molecular weight (M W) of 197.30 kDa was first metal complexed and then degraded into five CTSs with M W of 107.90, 56.48, 10.40, 5.67 (CTS-4) and 3.66 kDa. Decrease of M W did not cause a significant change in chemical structure of the residue CTS, but the crystal structure was transformed significantly. The moisture retention increased firstly and then decreased as the M W of CTS decreased. CTS-4 was superior to CTSs with other M W and propylene glycol in terms of the moisture retention. The lower water activity and increase of net isosteric heat were observed in CTS-4, which was due to the migration of immobilized water to a bound-state caused by mounting newly formed chain-end hydrophilic groups per unit weight. CTS-4 could effectively improve moisture retention, showing a potential to substitute commonly used humectant such as propylene glycol. [ABSTRACT FROM AUTHOR]

[Display omitted] Browning can occur in the matrices of alditol and amino acids due to heating or long-term storage, which poses challenges in achieving the desired appearance stability. To investigate the mechanism of browning in the sorbitol-glycine system, we evaluated the evolution of typical intermediates, including glucose and α-dicarbonyl compounds (α-DCs), during heating at 100 ˚C. The browning index and intermediate products of the sorbitol-glycine system increased more rapidly compared to those of the sorbitol system. After heating for 10 h, the browning index of the sorbitol-glycine system was eight times higher than that of sorbitol alone. In the presence of glycine, sorbitol underwent continuous conversion into glucose. After 10 h of heating, the concentration of glucose in the sorbitol-glycine system reanched 726.6 mg/L, which was approximately 63 times higher than that in the sorbitol system. Mass spectrometry analysis revealed the presence of α-DCs such as 3-deoxyglucosone (3-DG), glyoxal (GO), methylglyoxal (MGO), 2,3-butanedione (2,3-BD), in the sorbitol-glycine system. These compounds were precursors of melanoidins, indicating the occurrence of the Maillard reaction and resulting in the browning of the system. Therefore, the browning process in the sorbitol-glycine system involved two stages of reactions: the conversion of sorbitol to glucose and the Maillard reaction between glucose and glycine. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-stage heating improved the tenderness and juiciness of meat. • Preheating at 60 ℃ induced the dissociation of actomyosin of pork. • The unfolding of actomyosin promoted the liberation of actin. The effects of two-stage heating with different preheating combinations on the shear force and water status of pork-pieces were explored. The results showed that the combined preheating at 50 ℃ for 35 min or at 60 ℃ for 5 or 20 min with traditional high temperature heating reduced the shear force and improved the water retention of meat, which was attributed to uniformly separation of myofibers and smaller myofiber space. Visible dissociation of actomyosin in heating groups of 50 ℃-35 min, and 60 ℃-5, 20 min was related to the tenderization of meat. The higher surface hydrophobicity, tryptophan fluorescence intensity, and lower α-helices of actomyosin at 60 ℃ contributed to the liberation of actin. However, severe oxidation of sulfhydryl groups at 70 ℃ and 80 ℃ promoted the aggregation of actomyosin. This study presents the advantage of two-stage heating in improving meat tenderness and juiciness and its underlying mechanisms. [ABSTRACT FROM AUTHOR]

The characteristic aroma compounds of traditional braised pork were investigated by gas chromatography–mass spectrometry−olfactometry (GC–MS–O), odor-activity values, and aroma recombination and omission experiments. A total of 56 volatile compounds were detected by GC–MS, among which hexanal, octanal, nonanal, (E)-2-octenal, 2,3-octanedione, 1-octen-3-ol, 2-pentylfuran, methanethiol, and dimethyl trisulfide were identified as the key aroma compounds by molecular sensory science. Partial least squares regression analysis indicated that some aroma compounds significantly contributed to fatty (hexanal, heptanal, 2-pentylfuran, nonanal, and (E)-2-octenal), meaty (methanethiol, dimethyl disulfide, dimethyl trisulfide, and octanal), sauce-like flavor (3-hydroxy-2-butanone and 2-furfural), and sweet, caramel (2,3-octanedione, 1-octen-3-ol). Lean meat produced more aldehydes, alcohols, ketones, and sulfur-containing compounds than subcutaneous fat. The seasonings (saccharose, cooking wine, and soy sauce) facilitated the formation of ethyl L-lactate, 2-acetylfuran, 2-furfural, 5-methyl-2-furaldehyde, 2-methyl-pyrazine, and 2-acetylpyrrole. Meanwhile they reduced the content of lipid oxidation products, thereby stimulated the characteristic aroma of the Chinese traditional braised pork. [Display omitted] • Key aroma compounds in braised pork were identified by molecular sensory science. • PLSR analysis revealed correlation between aroma compounds and sensory quality. • PLSR analysis can serve as complementary method of molecular sensory science. • Lean meat produced more aroma compounds than subcutaneous fat. • Seasonings improved flavor profile by weakening excessive lipid oxidation. [ABSTRACT FROM AUTHOR]

The stability of coffee's characteristic aroma was investigated during half an hour incubation of coffee brew, revealing that thiols, including 2-furfurylthiol (2-FFT), 2-methyl-3-furanthiol (2M3F), and methanethiol (MET), experienced reductions to 3.3%, 34.4%, and 25.5%, respectively. To identify the dominant components responsible for the reduction of aromas, the effects of coffee lipids, hydroxyhydroquinone, melanoidin of varying molecular sizes, and carbohydrates on selected characteristic aroma compounds were evaluated in a mimic coffee model. It was proposed that higher amounts of lipids generally led to a reduction in coffee aromas, particularly those with a positive oil-water partition coefficient. Among potential aroma-binding precursors, hydroxyhydroquinone, a thermal degradation product of chlorogenic acid, exhibited the highest correlation with the loss of 2-FFT and 2M3F. In contrast, the reduction of aromas such as MET, 2,3-butanedione, 2,5-dimethylpyrazine, dimethyl trisulfide, and difurfuryl disulfide was significantly negatively correlated with melanoidin, especially low molecular weight melanoidin (<3 kD). The binding reaction between hydroxyhydroquinone and 2-furfurylthiol was further investigated in brewed coffee, demonstrating that quinones, the oxidation products of hydroxyhydroquinone, exhibited a higher reactivity, directly reacting with 2-furfurylthiol, which was the primary reactant for 2-furfurylthiol. • The dominant coffee aroma binding factors were studied in a mimic coffee model. • The direct reactant of 2-furfurylthiol in coffee brew was further screened. • The aroma changes effected by coffee lipids was studied in a mimic coffee model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gradient-temperature cooking regime improved the tenderness of braised pork. • Preheating at 50–60 °C weakened shrinkage of myofibrils during pressure heating. • Subsequent slow heating at low pressure weakened the aggregation of protein. • Myofiber network formed by this regime increased immobilized water retention. A novel gradient-temperature heating regime was proposed to improve the texture of braised pork. Compared with one-stage pressure heat treatment of around 107 °C, the gradient-temperature heat regime of preheating at 60 °C, followed by a slow increase of temperature to 107 °C and simmering at 97 °C increased the retention of immobilized water and reduced the shear force of meat. In this cooking regime, preheating treatment at 50–60 °C could promote the dissociation of thin and thick myofilaments, which contributed to a weakened shrinkage of myofibrils during the subsequent high temperature heating process. Pressure-heating treatment with a slow increasing temperature and the medium-temperature simmering significantly reduced (p < 0.05) the oxidation of sulfhydryl groups and the loss of α-helical, which weakened the excessive aggregation of protein and promoted the formation of myofibril network. Both the weakened shrinkage and the formation of myofibril network during gradient-temperature heating contributed to the decreased shear force and an increased immobilized water. Hence, the reduction of the oxidation and aggregation of the proteins is the key to improve the tenderness of the braised meat. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extra amino substrates improved the concentration and varieties of pyrazine. • High temperature and alkaline pH further increased the generation of pyrazine. • Methylglyoxal other than glyoxal was the main precursor for pyrazine formation. The Amadori compound of glucose and l -alanyl- l -glutamine (Ala-Gln-ARP) was prepared and characterized by UPLC-MS/MS and NMR. There were no pyrazines produced by heated Ala-Gln-ARP alone due to the asynchronicity of regenerated l -alanyl- l -glutamine and α -dicarbonyl compounds. High temperature (130 °C) and long reaction time could facilitate the 2,5-dimethylpyrazine formation at a small concentration (33.4 ± 3.47 μg/L). The exogenous amino substrates would lower the formation temperature of pyrazines and make it to be generated effectively. Extra supplied l -alanyl- l -glutamine could generate 2,5-dimethylpyrazine at 110 °C, while higher temperature of 140 °C could strengthen the formation of 2,5-dimethylpyrazine (793 ± 119 μg/L) and stimulate the generation of other pyrazines, including methylpyrazine and 2,6-dimethylpyrazine. The exogenous alanine, glutamic acid, and glutamine was also beneficial to enhance the pyrazines formation, especially the glutamic acid. Furthermore, alkaline pH of thermal reaction made pyrazines increase significantly than in neutral medium and further enriched their species such as unsubstituted pyrazine and trimethylpyrazine. [ABSTRACT FROM AUTHOR]

A novel long-acting antifungal active film was successfully created, as an alternative to conventional chemical food preservatives. The antifungal films incorporated with cinnamaldehyde (CA) microcapsules achieved long-lasting antifungal activity, mitigated yellowing caused by the direct addition of CA, and showed improved flexibility properties. CA multinuclear microcapsules were produced using gelatin with a Bloom value of 200 and gum Arabic, resulting in increased encapsulation efficiency (99.86 %), good dispersibility and enhanced antifungal ability (inhibition zone diameter of 32 mm). These microcapsules can be incorporated into films as a sustained-release antifungal agent. Compared to unencapsulated CA, the addition of 1 % CA microcapsules reduced the ultraviolet transmittance (<36.40 %) of the film while maintaining visible-light transmittance (36.40 %–65.20 %), and improving its elongation at break (23.49 %). The water vapor permeability of the film was not affected by the inclusion of CA microcapsules below 0.25 %. Moreover, microcapsules can enhance the thermal properties of the film. Antifungal films incorporated with 0.5 %–2 % microcapsules may offer better long-acting inhibition against A. brasiliensis. This study presents a new promising pathway for food storage. [Display omitted] • The microcapsules prepared by gelatin (200 Bloom) had the largest inhibition zone. • The addition of microcapsules improved the flexibility of the film. • The films with the addition of microcapsules exhibited excellent long-lasting antifungal. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the distribution pattern and migration pathway of sodium ion in the myofibrillar protein (MP) gel matrix during microwave heating. The results showed that the content of sodium ions in the outer layer of MP gel increased by 47.85% compared with that in the inner layer. In the inner layer of protein gel, the non-covalent disulfide bonds (mainly ε(γ-Glu)-Lys) increased (P < 0.05), which contributed to the formation of a better rigid structure of the protein. The free water content was significantly higher than that of the inner layer (P < 0.05), which was related to the higher mobility of sodium ions. The results of microstructure analysis showed that the outer layer of the MP gel formed a more porous network than the inner layer. This work is expected to give some insights into the development of promising salt-reduced meat products by microwave heating. [Display omitted] • Microwave heating enhanced inhomogeneous distribution of sodium in protein gels. • The sodium migration was related to water mobility and protein aggregation of gel. • The loose and porous microstructure was formed in the rapidly warming region of the gel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Key aroma compounds of braised pork were identified by molecular sensory science. • PLSR clarified the contribution of key aroma compounds to sensory attributes. • Better aroma profile was achieved by fire cooking rather than induction cooker. • More key aroma compounds derived from lean meat due to its higher phospholipid. • Electromagnetic heating parameters significantly affected key aroma formation. The characteristic aroma compounds of braised pork were identified through molecular sensory science and PLSR analysis, and the difference between two cooking methods, traditional open-fire (BPF) and induction cooker (BPC), was compared. Seventeen aroma compounds with odor activity values (OAVs) > 1 were identified in both samples. BPF revealed higher OAVs for most of the aroma compounds compared to BPC, and the higher aroma quality. Aroma recombination and omission experiments confirmed that twelve aroma compounds significantly contributed to the characteristic aroma of braised pork, and eight compounds such as hexanal, (E)-2-octenal, and methanethiol were further confirmed as important contributors by PLSR analysis. Furthermore, PLSR analysis clarified the role of aldehydes such as hexanal, (E)-2-octenal, and (E , E)-2,4-decadienal in contributing to fatty attribute, whereas methanethiol was responsible for the meaty aroma. These characteristic aroma compounds mainly derived from lean meat due to its high content of phospholipids, and the exogenous seasonings contributed to the balanced characteristic aroma profile of braised pork by altering the distribution of these characteristic aroma compounds. Variations in heating parameters affected the formation of lipid oxidation and Strecker degradation products, which might explain aroma discrepancy between braised pork cooked by two methods with different heat transfer efficiencies. [ABSTRACT FROM AUTHOR]

• The calculated results show that SbP exhibits superior gas sensing performance to SO 2. • Orbital hybridization is the main reason for strong interaction between SbP and SO 2. • SbP is suitable for SO 2 gas sensing by comparing adsorption of different substrates. We theoretically explored the possibility of monolayer antimonide phosphorus (SbP) detecting SF 6 decomposition components based on the first-principles calculations. The calculated results indicate that monolayer SbP exhibits more excellent gas sensing performance to SO 2 than to other gas molecules, with the adsorption energy of −0.541 eV and the charge transfer of −0.232 e. In addition, we predict that SbP is suitable for SO 2 sensing to detect SF 6 decompositions by comparing adsorption energy and charge transfer of different substrates. Therefore, monolayer SbP can be a promising candidate for high sensitivity SO 2 sensor to detect SF 6 decompositions. [ABSTRACT FROM AUTHOR]

• 2D SiAs 2 /GeP 2 heterostructure shows substantial absorption in both visible and UV light regions. • 2D penta-SiAs 2 /penta-GeP 2 heterostructure possesses a typical type-II band alignment. • A considerable power conversion efficiency of 12.1% endows the SiAs2/GeP2 heterostructure promising for solar cell. The two-dimensional (2D) materials offer tremendous opportunities for efficient, ultrathin solar cells beyond conventional three-dimensional materials. In this work, we study the interfacial electrical properties and charge transfer characteristics of the SiAs 2 /GeP 2 heterostructure by first-principles calculations. The SiAs 2 /GeP 2 heterostructure shows a 2.25 eV bandgap and pronounced solar light absorption. Furthermore, the heterostructure presents a type-II alignment, and possesses a desirable power conversion efficiency (PCE) of up to 12.1%. These results reveal that SiAs 2 /GeP 2 is promising for solar energy conversion in photovoltaic applications, and also provide a possible alternative for experiment scheme. [ABSTRACT FROM AUTHOR]

Abstract To further explore the aroma mechanism of Chinese faint-scent cigarettes, the contribution of tobacco leaf composition, including six kinds of saccharides, eight tobacco alkaloids, seventeen kinds of organic acids, eighteen kinds of amino acids and four ions (Na+, K+, Mg2+ and Ca2+), on aroma quality characteristic (freshness, flowery and acidic notes) of faint-scent cigarettes was analyzed by chromatography and PLSR. The results showed that (i) xylose, fructose, glucose, maltose and sucrose were negatively correlated to acidic note, while galactose showed significantly positive correlation to acidic note. (ii) Phenylalanine and proline showed significant and positive correlation with characteristic aromas. Proline contributed to freshness and flowery, while leucine significantly contributed to acidic note. (iii) Most organic acids were significantly correlated to characteristic aromas. Palmitic acid and stearic acid contributed to the freshness, while dodecanoic acid and palmitic acid significantly contributed to flowery. (iv) Tobacco Na ion plays negative and significant correlation to acidic note. Highlights • Most saccharides were negatively correlated to acidic note of cigarettes. • Phenylalanine and proline were positively correlated to characteristic aromas. • Proline, palmitic acid and stearic acid contributed to the freshness. • Proline, dodecanoic acid and palmitic acid significantly contributed to flowery. • Tobacco Na ion has negative and significant correlation to acidic note. [ABSTRACT FROM AUTHOR]

[Display omitted] • Raman spectra can be used to rapidly test the degree of unsaturation during heating. • The early event of radical formation in pork belly during processing were evaluated. • Unsaturated fatty acids and oxidation products positively relate to aldehyde content. • The collection and synergy of taste-active compounds improved the umami and richness. This study investigated the mechanisms underlying the evolution and formation of aroma and taste-active compounds of pork belly in representative traditional pork cuisines during pan-heating. The results revealed that as the temperature increased to 110 ℃, the unsaturation of fatty acids decreased from 60.25 % to 58.71 %, while the content of free radicals and secondary oxidation products increased. At the later heating stages, the addition of spices and increased heating temperature (150 ℃) led to continuous increments in the contents (from 958.20 μg/kg to 1511.88 μg/kg) and diversity of volatile compounds in pork belly, imparting the unique aroma. Additionally, the accumulation of low-molecular-weight peptides, free amino acids, and nucleotides not only provided the substrate for thermal reactions and their synergistic effects, but also contributed to the desired taste quality. These findings offered insights into the flavor formation mechanisms of traditional pork cuisines and provided direction for further research. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shifts of α-helix to β-sheet decreased the water-holding capacity of lean meat. • The occurrence of heat-induced protein oxidation toughened the lean meat. • Immobilized water was responsible for the softness of lean meat. • The rupture of perimysium structure enhanced the tenderness of lean meat. Tenderness of lean meat in braised pork is of great importance to the consumer palatability and acceptance. The influence of water status, protein structure and histological changes on lean meat tenderness during cooking was investigated. Results indicated that lean meat began to tenderize mainly after 20 min-cooking. In the early period of cooking, the decrease of total sulfhydryl content caused the protein oxidative cross-linking, leading to the gradual unfolding of the protein structure, thus resulting in a decrease of T 22 and an increase of centrifugal loss, which decreased the tenderness of lean meat. However, after cooking for 20 min, the β-sheet decreased and random coil increased, thus generating conversion between P 21 and P 22. The rupture of perimysium structure was observed. Changes in protein structure, water status, and tissue histology could facilitate the initiation and development of lean meat tenderness. [ABSTRACT FROM AUTHOR]

We systematically investigate the electronic properties the two-dimensional (2D) silicene/GaP heterobilayer by using density functional theory calculations. We find the silicene and GaP monolayer are bounded to each other via orbital hybridization, and the charge redistribution occurring at the silicene/GaP interface leads to the opening of a direct energy band gap of about 0.997 eV in silicene. Importantly, by applying external electric field, the band structure of silicene/GaP heterostructure can be effectively modulated, and a semiconductor-metal transition even emerges. These intriguing properties make the silicene/GaP heterobilayer a promising 2D material for future electronics and strain sensors. [ABSTRACT FROM AUTHOR]

• Asynchronism between regenerative cysteine and fragments of deoxyosones led to the block of Strecker degradation. • Added xylose intensified the original flavor compounds derived from TTCA model under 100 °C. • Released Cys catalyzed the transformation from extra-added Xyl to more carbohydrate fragments. • Higher temperature was beneficial to the thermal degradation of Cys and provided more sulfur elements. • Effect of elevated temperature and added xylose on flavor improvement was confirmed by isotope labeling technique. The flavor intensity of thermally processed 2‑threityl-thiazolidine-4-carboxylic acid (TTCA) was significantly improved to 1.56 times of that generated from MRPs, but its flavor profile was not as desirable as that of fresh MRPs. The synergistic effect between the additional xylose (Xyl) and elevated temperature was proposed and confirmed via the quantitative analyses of regenerative cysteine (Cys) and fragments of deoxyosones (MGO/GO), which reduced the asynchronism between the formation of released Cys from degraded TTCA and retro -aldolisation products of the intermediate deoxyosones. This synergistic effect further enhanced the Strecker degradation of Cys as well as its thermal degradation and thereby promoted the formation of characteristic flavor substances including sulfur-containing compounds and pyrazines, and the total concentrations of TTCA reaction model reached 205.954 μg/L with additional Xyl at 140 °C. Model reaction systems were employed to verify this hypothesis and the proposed mechanism was further elucidated through isotope labeling technique. [ABSTRACT FROM AUTHOR]

• The retention rate of cinnamaldehyde was 15 %∼20 % higher than that of eugenol. • The Schiff base reaction led to formation of elastic-dominated interfacial layers. • The viscous dominant weak interfacial layers were formed in the presence of eugenol. The addition of tea seed oil improved storage stability and retention rate of HIPPEs. • Cinnamaldehyde-loaded HIPPEs had better storage stability than eugenol-loaded HIPPEs. This work aimed to investigate the encapsulation and stabilization mechanism of cinnamaldehyde and eugenol in high internal phase Pickering emulsions (HIPPEs) through regulating their interfacial rheological properties and interfacial microstructure. With the incorporation of cinnamaldehyde, the Schiff base reaction between the cinnamaldehyde and proteins favored the formation of the predominantly elastic and solid-like interfacial layers. In contrast, the hydrogen bonds between eugenol and proteins resulted in the transformation of interfacial layers to viscous dominant with weak viscoelastic responses. Thus, cinnamaldehyde-loaded HIPPEs had a better storage stability than eugenol-loaded HIPPEs, and the retention rate was increased by about 15 %∼20 %. The addition of tea camellia seed oil inhibited the mobility of immobilized water and improved the retention rates of cinnamaldehyde and eugenol by approximately 6 % and 12 % (30 days at 25 °C), respectively. These findings will be beneficial for the development and design of effective essential oil encapsulation systems in the food industry. [ABSTRACT FROM AUTHOR]

• The bandgaps of the hybridized (ABNM) 2 -(AC 3 BM) n monolayers can be tuned from 1.031 to 0.835 eV by increasing the number of AC 3 BM units. • The electronic properties of (ABNM) 2 -(AC 3 BM) 2 monolayer can be effectively regulated by external strain and electric field. • The absorption rate of visible part of the spectrum has increased in scope and intensity with the increment of AC 3 BM units. To extend the application range of h-BN monolayer which possesses a wide bandgap (5.9 eV), constructing lateral heterostructures is proved to be a feasible and novel method. Here, considering C 3 B monolayer possessing an indirect narrow bandgap (0.67 eV), the lateral heterostructure is proposed by using h-BN monolayer to hybridize with C 3 B monolayer. The structural, electronic, optical and transport properties of the h-BN/C 3 B lateral heterostructures are systematically investigated by performing first-principles calculation. The calculated results demonstrate that the electronic properties of the studied lateral heterostructures can be easily modulated by strain and external electric field. Specifically, the (ABNM) 2 -(AC 3 BM) 2 exhibits metal-to-semiconductor transition under different strain conditions and the bandgap of the (ABNM) 2 -(AC 3 BM) 2 can be adjusted from 1.03 to 2.62 eV by applying external electric field vertically. In addition, the optical calculations reveal that (ABNM) 2 -(AC 3 BM) n behave outstanding optical-absorption capacity in visible region. Furthermore, the calculated asymmetrical carrier effective masses suggest that the migratory directions of electron and hole are parallel to the interface. These highly-tunable electronic properties and favorable optical performances of the (ABNM) 2 -(AC 3 BM) n lateral heterojunctions may facilitate their practical applications for nanoelectronics and optoelectronics. [ABSTRACT FROM AUTHOR]

The methionine/glucose (Met/Glc) and methionine/glucose-derived Amadori rearrangement product (MG-ARP) models were established to analyze their differences in flavor profiles and aroma potentiality. The principal component analysis revealed the advantage of MG-ARP in the formation of low temperature-induced processing flavor. MG-ARP exhibited superior potential in the rapid formation and high intensity of processed flavor than the Met/Glc except for the inefficiency in pyrazine production. The extra-added Glc tended to react with recovered Met to compete against α-dicarbonyl compounds to suppress the Strecker degradation and pyrazine formation. The additional Met effectively improved the precursor availability and facilitated the conversion of C 6 -α-dicarbonyl compounds to short-chained α-dicarbonyl compounds for pyrazine formation rather than their dehydration and cyclization to generate furans. The oxidation of Met favored the nonoxidative carbohydrate degradation leading to MGO formation and the aldolization of dihydropyrazines, which synergistically enriched the varieties of pyrazines, especially for the promoted formation of long-chain substituted pyrazines., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Lysine (Lys) glycated by xylose (Xyl) at α-NH 2 [ N α (1-deoxy-D-xylulos-1-yl)lysine ( N α -Xyl-Lys ARP)] or ε-NH 2 [ N ε -(1-deoxy-D-xylulos-1-yl)lysine ( N ε -Xyl-Lys ARP)] significantly impacted the thermal degradation pathways of Amadori rearrangement products (ARPs). N α -Xyl-Lys ARP was found to undergo retro-aldolization on the sugar fragment more readily to form glyoxal/methylglyoxal than N ε -Xyl-Lys ARP. Furans and pyrazines formation during the degradation of the diglycated lysine [ N α , N ε -di(1-deoxy-d-xylulos-1-yl)lysine ( N α ,N ε -di-Xyl-Lys ARP)] was delayed at 120 °C relative to N ε -Xyl-Lys ARP. This was attributed to the complex degradation of N α ,N ε -di-Xyl-Lys ARP, which slowed the substantial formation of deoxypentosones and the effective release of Lys. At 140 °C, the dual glycated N α ,N ε -di-Xyl-Lys ARP was more conducive to promoting the redistribution of electrons and facilitating molecular rearrangement. This accelerated the efficient decomposition of dual glycated groups in N α ,N ε -di-Xyl-Lys ARP and enabled glyoxal to actively participate in Strecker degradation. Thus, the production of furans and pyrazines was substantially increased, and the variety of pyrazines was expanded from three types to eight types. An appropriate increase to pH 7.5 effectively avoided the overprotonation of hydroxyl and amino groups (pH 5.5), simultaneously enhancing furans and pyrazines yield while minimizing the formation of pyridines under alkaline conditions.

The formation pathway and mechanism of various pyrazines were investigated during the thermal treatment of the alanine-xylose Amadori compound (Ala-ARP) and exogenous alanine (Ala). 15 N -labeled Ala was used to coheated with Ala-ARP to clarify the nitrogen sources and the respective contributions of exogenous Ala and the regenerated Ala released from Ala-ARP to different pyrazine formation. It was found that exogenous Ala exhibited a priority in capturing glyoxal (GO) to form pyrazine during the thermal degradation of ARP. Compared to the Ala-methylglyoxal (MGO) model, a lower activation energy was required for the Ala-GO reaction, where the reaction dynamics of Ala-GO followed a zero-order model. In addition to forming pyrazine, the interaction between existing exogenous Ala and GO would accelerate the thermal degradation of Ala-ARP and retro-aldolization reaction of deoxyxylosones (DXs) to α-dicarbonyls. During this process, the release of regenerated Ala and MGO was promoted. Accordingly, as GO was expended by exogenous Ala during the initial stage of ARP-Ala degradation, the condensation between regenerated Ala and MGO became intensified, leading to the generation of methylpyrazine and 2,5-dimethylpyrazine. As a result, in the thermally treated mixture of Ala-ARP and exogenous Ala, 55% of the formed pyrazine originated from exogenous Ala, while 63% of the formed methylpyrazine and 57% of the formed 2,5-dimethylpyrazine were derived from regenerated Ala (120 °C, 30 min).

Amadori rearrangement products (ARPs) are gaining more attention for their potential usage in the food flavor industry. Peptide-ARPs have been studied, but pyrazinones that were theoretically found in the Maillard reaction (MR) have not been reported to be formed from small peptide-ARPs. This study found four pyrazinones: 1-methyl-, 1,5-dimethyl-, 1,6-dimethyl-, and 1,5,6-trimethyl-2(1 H )-pyrazinones in both MR and ARP systems. It was the first time 1-methyl-2(1 H )-pyrazinone was reported, along with 1,5-dimethyl- and 1,5,6-trimethyl-2(1 H )-pyrazinones being purified and analyzed by nuclear magnetic resonance for the first time. The primary formation routes of the pyrazinones were also proven as the reaction between diglycine and α-dicarbonyls, including glyoxal, methylglyoxal, and diacetyl. The pyrazinones, especially 1,5-dimethyl-2(1 H )-pyrazinone, have strong fluorescence intensity, which may be the reason for the increase of fluorescence intensity in MR besides α-dicarbonyls. Cytotoxicity analysis showed that both Gly-/Digly-/Trigly-ARP and the three pyrazinones [1-methyl-, 1,5-dimethyl-, and 1,5,6-trimethyl-2(1 H )-pyrazinones] showed no prominent cytotoxicity in the HepG2 cell line below 100 μg/mL, further suggesting that ARPs or pyrazinones could be used as flavor additives in the future. Further research should be conducted to investigate pyrazinones in various systems, especially the peptide-ARPs, which are ubiquitous in real food systems.

Directional and rapid formation of the Amadori rearrangement product (ARP) from the glutamic acid and xylose was achieved through intermittent microwave heating. The yield of ARP reached 58.09 % by subjecting the system to intermittent microwave heating at a power density of 10 W/g for 14 min. Dehydration rate and microwave effects were found to be key factors to optimize the conditions for directional and rapid preparation of the ARP. Through a comprehensive analysis of the ARP degradation and further browning under both conductive and microwave thermal processing, it was observed that microwave processing significantly accelerated the browning degree of systems, leading to a tenfold reduction in the heating time required for browning. This research presented a promising avenue for the development of novel and expedited methods for the production of ARP and highlighted the potential of ARP in enhancing color quality in fast-cooking applications utilizing microwave., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Dihydromyricetin (DMY) was employed to reduce the yield of furfural derived from the Amadori rearrangement product of l-threonine and d-xylose (Thr-ARP) by trapping Thr-ARP, 3-deoxyxyosone (3-DX), and furfural to form adducts. The effect of different concentrations of DMY at different pH values and temperatures on the reduction of furfural production was studied, and the results showed that DMY could significantly reduce furfural production at higher pH (pH 5-7) and lower temperature (110 °C). Through the surface electrostatic potential analysis by Gaussian, a significant enhancement of the C 6 nucleophilic ability at higher pH (pH ≥ 5) was observed on DMY with hydrogen-dissociated phenol hydroxyl. The nucleophilic ability of DMY led to its trapping of Thr-ARP, 3-DX, and furfural with the generation of the adducts DMY-Thr-ARP, DMY-3-DX, and DMY-furfural. The formation of the DMY-Thr-ARP adduct slowed the degradation of Thr-ARP, caused the decrease of the 3-DX yield, and thereby inhibited the conversion of 3-DX to furfural. Therefore, DMY-Thr-ARP was purified, and the structure was identified by nuclear magnetic resonance (NMR). The results confirmed that C 6 or C 8 of DMY and carbonyl carbon in Thr-ARP underwent a nucleophilic addition reaction to form the DMY-Thr-ARP adduct. In combination with the analysis results of Gaussian, most of the DMY-Thr-ARP adducts were calculated to be C 6 -DMY-Thr-ARP. Furthermore, the formation of DMY-furfural caused furfural consumption. The formation of the adducts also shunted the pathway of both Thr-ARP and 3-DX conversion to furfural, resulting in a decrease in the level of furfural production.

The involvement of exogenous alanine was observed to inhibit the generation of 2-furfural during the thermal degradation of the Amadori rearrangement product (ARP). To clarify the reason for the reduced yield of 2-furfural triggered by exogenous alanine, the evolution of the precursors of 2-furfural formed in the ARP model and ARP-alanine model was investigated, and a model including ARP and 15 N -labeled alanine was used to differentiate the role of endogenous and exogenous alanine in the degradation of ARP. It was found that the condensation between ARP and 3-deoxyxylosone could occur during thermal treatment. Nevertheless, the interaction of ARP with 3-deoxyxylosone exhibited an accelerated pace in the presence of exogenous alanine. In this way, exogenous alanine blocked the recovery of endogenous alanine while simultaneously enhancing the consumption of ARP and 3-deoxyxylosone during the Maillard reaction. Hence, the yield of 2-furfural was diminished with the interference of exogenous alanine. Furthermore, the promotion of the reaction between ARP and deoxyxylosone induced by exogenous alanine blocked their retro-aldolization reaction to short-chain α-dicarbonyls (α-DCs) and consequently resulted in a lack of pyrazine formation during the ARP degradation. The present study provided a feasible method for the controlled formation of 2-furfural during the thermal treatment of ARP derived from alanine.

Efficient and rapid screening of target materials in a vast material space remains a significant challenge in the field of materials science. In this study, first-principles calculations and machine learning algorithms are performed to search for high out-of-plane piezoelectric stress coefficient materials in the MXene functional database among the 1757 groups of noncentrosymmetric MXenes with nonzero band gaps, which meet the criteria for piezoelectric properties. For the monatomic MXene testing set, the random forest regression (RFR), gradient boosting regression (GBR), support vector regression (SVR), and multilayer perceptron regression (MLPR) exhibit R 2 values of 0.80, 0.80, 0.89, and 0.87, respectively. Expanding our analysis to the entire MXene data set, the best active learning cycle finds more than 140 and 22 MXenes with out-of-plane piezoelectric stress coefficients ( e 31 ) exceeding 3 × 10 -10 and 5 × 10 -10 C/m, respectively. Moreover, thermodynamic stabilities were confirmed in 22 MXenes with giant piezoelectric stress coefficients and 9 MXenes with both large in-plane ( d 11 > 15 pm/V) and out-of-plane ( d 31 > 2 pm/V) piezoelectric strain coefficients. These findings highlight the remarkable capabilities of machine learning and its optimization algorithms in accelerating the discovery of novel piezoelectric materials, and MXene materials emerge as highly promising candidates for piezoelectric materials.

The efficient preparation of the ribose-glutathione (Rib-GSH) Amadori rearrangement product (RG-ARP) as a potent precursor of meaty flavor was studied through the atmospheric-vacuum thermal reaction. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that the oxidation and degradation of GSH occurred during the preparation of RG-ARP via the atmospheric thermal reaction, especially at a low molar ratio of Rib to GSH and high reaction temperature. The RG-ARP and the ARPs derived from the products of GSH oxidation and degradation with the participation of Rib were identified by MS/MS as N -(1-deoxy-d-ribulos-1-yl)-glutathione, N -(1-deoxy-d-ribulos-1-yl)-cysteinylglycine, and N -(1-deoxy-d-ribulos-1-yl)-glutathione disulfide. The selective formation of RG-ARP was disrupted due to the multiple consumption pathways of GSH and Rib. The removal of water and the reduction of oxygen content during vacuum dehydration exhibited an obvious inhibitory effect on the oxidation of cysteinyl and the cleavage of glutamyl, limiting the oxidation and degradation of GSH. Meanwhile, the rapid evaporation of water promoted the molecular collision between the reactants, which allowed the glycation reaction of GSH to be advanced and fragmentation of RG-ARP to be inhibited at a mild dehydration temperature. Accordingly, the atmospheric-vacuum thermal reaction was proposed to limit the generation of secondary byproducts and enhance the yield of RG-ARP, enabling the RG-ARP yield to reach 49.23% at 80 °C and a molar ratio of 2:1 (Rib/GSH) for 20 min.

Maillard reaction intermediates (MRIs) derived from enzymatic hydrolysates of soybean protein were prepared by combining dehydration method with spray drying and vacuum drying. Taste characteristics, browning precursors, water activity, and moisture state were monitored during the process of vacuum drying. The water activity was significantly reduced and the proportion of bound water was increased, which could promote the large accumulation of MRIs. The saltiness, umami, and bitterness responses of MRIs were all reduced and the reduction of taste intensity during vacuum drying was probably caused by the reaction of small peptides of taste-active amino acids with glucose. The continuous accumulation of browning precursors during vacuum drying was confirmed by fluorescence spectroscopic analysis and by quantitative analysis of α-dicarbonyl compounds. Subsequent browning reactions further demonstrated that the MRI with the highest fluorescence intensity also had the greatest browning potential., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Industrial production, environmental monitoring, and clinical medicine put forward urgent demands for high-performance gas sensors. Two-dimensional (2D) materials are regarded as promising gas-sensing materials owing to their large surface-to-volume ratio, high surface activity, and abundant surface-active sites. However, it is still challenging to achieve facilely prepared materials with high sensitivity, fast response, full recovery, and robustness in harsh environments for gas sensing. Here, a combination of experiments and density functional theory (DFT) calculations is performed to explore the application of tellurene in gas sensors. The prepared tellurene nanoflakes via facile liquid-phase exfoliation show an excellent response to NO 2 (25 ppb, 201.8% and 150 ppb, 264.3%) and an ultralow theory detection limit (DL) of 0.214 ppb at room temperature, which is excellent compared to that of most reported 2D materials. Furthermore, tellurene sensors present a fast response (25 ppb, 83 s and 100 ppb, 26 s) and recovery (25 ppb, 458 s and 100 ppb, 290 s). The DFT calculations further clarify the reasons for enhanced electrical conductivity after NO 2 adsorption because of the interfacial electron transfer from tellurene to NO 2 , revealing an underlying explanation for tellurene-based gas sensors. These results indicate that tellurene is eminently promising for detecting NO 2 with superior sensitivity, favorable selectivity, an ultralow DL, fast response-recovery, and high stability.

The interaction mechanism of (-)-epigallocatechin gallate (EGCG) with Amadori compound (Amadori rearrangement product, ARP) in xylose-alanine model reaction systems was investigated. The adducts between ARP and EGCG were identified as two ARP-EGCG isomers, two ARP-EGCG-H 2 O isomers, and multiple ARP-deoxypentosone (DP)-EGCG isomers. The structure of an isolated and purified ARP-EGCG adduct was analyzed by means of Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, liquid chromatography-time-of-flight (TOF)-mass spectrometry (LC-TOF-MS), and nuclear magnetic resonance (NMR). Using the two-dimensional NMR analyses, the structure of ARP-EGCG adducts was clarified to consist of a covalent linkage between the C 12 position of the ARP and the C 8 position of the A-ring of EGCG, presumably generated by the nucleophilic nature of the EGCG or aromatic substitution reactions. The results showed that slightly alkaline pH and higher temperature could facilitate this reaction. Additionally, the thermal stability of ARP-EGCG and its degradation products revealed that the decomposition pathways of this adduct altered the classic decomposition pathway of ARP, resulting in a lower browning rate and blocking the subsequent Maillard reaction.

(-)-Epigallocatechin gallate (EGCG) had a significant effect on Maillard reaction intermediate formation in the xylose/alanine model system. A trapping effect of EGCG on the reactive deoxyosones was observed to change the reaction pathways. The rate constant of Amadori rearrangement product (ARP) conversion to deoxyosones was decreased with EGCG addition, indicating an inhibition of ARP degradation. Dehydration improved the ARP formation during the thermal reaction and synergistically improved the yield of ARP with the EGCG trapping effect on the deoxyosones. Additionally, EGCG decreased the activation energy for the conversion of xylose/alanine to ARP (from 77.8 to 62.8 kJ/mol) and in turn accelerated the ARP formation. The effect of EGCG was further facilitated at the optimal conditions of 90 °C, at pH 7.5, and a molar ratio of xylose to alanine of 2:1, which improved the yield of ARP ( N -(1-deoxy-d-xylulos-1-yl)alanine) from 2 to 95%.

The formation conditions of the Amadori compound (ARP) N-(1-deoxy-d-xylulos-1-yl)-alanine were determined in an aqueous Maillard reaction between l-alanine and d-xylose under a two-step temperature rising process with (-)-epigallocatechin gallate (EGCG) as an indicator followed by browning intensity detection of the final Maillard reaction products (MRPs). To clarify the mechanism of EGCG indication on the ARP formation, the change in the concentration of some key products generated during the Maillard reaction with EGCG addition was investigated. Results showed an inhibition effect of EGCG on the browning precursor formation through the generation of ARP-EGCG adducts and deoxyosone-EGCG adducts, which was proposed as an important pathway to inhibit browning during the Maillard reaction and to indicate ARP formation.

The Maillard reaction intermediate (MRI) and Maillard reaction products (MRPs) derived from xylose (Xyl) and phenylalanine (Phe) were prepared, then stored at 25 °C for 60 days. After storage, the contents of flavor compounds and the clarity of MRPs solution decreased, and the apparent Z-average hydrodynamic diameter (D h ) of particles in the solution increased from 149 to 439 nm. However, the MRI solution remained transparent during storage. The concentration of MRI only decreased by 6.49%, and A 294 of the solution increased slightly yet A 420 remained stable. Numerous flavor compounds in MRPs decreased during heat treatment, meanwhile the cross-linking and aggregation of MRPs were intensified, and the particles' D h increased to micron level. The heated MRI solution showed a similar appealing profile and flavor fingerprints as the MRPs solution before heat treatment. Controlled formation of flavors from MRIs is proposed to be used as potential alternative to the existing Maillard flavorings., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Exploring two-dimensional materials with novel properties is becoming particularly important due to their potential applications in future electronics and optoelectronics. In the current work, the electronic and optical properties of penta-Sn 3 H 2 are investigated by density-functional theory. By assessing the phonon spectrum, we find that penta-Sn 3 H 2 monolayer is energetically more favorable compared with pristine penta-stanene due to hydrogenation transforming the sp 2 -sp 3 hybrid orbitals into sp 3 hybridization. Our calculations revealed that penta-Sn 3 H 2 is a semiconductor with indirect band gaps of 1.48 eV according to the GGA functional (2.44 eV according to the HSE06 functional). Moreover, the electronic structures of penta-Sn 3 H 2 can be effectively modulated by biaxial tensile strain. Meanwhile, our calculations reveal that the indirect to direct band gap transition can be achieved in this monolayer sheet by >4% biaxial strain. On the other hand, the well-located band edge and visible light absorption make penta-Sn 3 H 2 a potentially promising optoelectronic material for photocatalytic water splitting., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)