Inhibitory effect of thiol compounds on browning precursors and intermediates in sorbitol/glycine system.

BACKGROUND: Sorbitol as a sweetener is often thought to be unable to participate in the Maillard reaction causing browning. However, browning of a system was found to be significant when sorbitol was mixed with glycine and heated. The thiol compounds glutathione and cysteine were added to the system, and the inhibition mechanism of the two on the browning of the system was studied by combining the changes of precursor substances, intermediate products and browning degree. RESULTS: When the concentration of thiol compounds reached 25 mg mL-1, both could make the browning inhibition of the system more than 80%, and the accumulated glucose concentration was reduced to <35% of the control. The production of 3-deoxyglucosone, a precursor of melanoidin, was significantly reduced. CONCLUSION: Glutathione and cysteine directly inhibited the production of substrates in the sorbitol/glycine system, reduced glucose accumulation through competitive consumption and captured highly active intermediates through sulfhydryl groups. This has implications for the browning control of food systems containing sugar alcohols. © 2024 Society of Chemical Industry.

Microencapsulation of essential oils by complex coacervation method: preparation, thermal stability, release properties and applications.

The microencapsulation of essential oils by complex coacervation continues to attract considerable attention due to high payload, increased thermal stability and sustained release of core materials. This review recapitulates the thermal properties of coacervates and essential oil microcapsules prepared by complex coacervation method using protein/polysaccharide and polysaccharide/polysaccharide. The authors discussed the factors affecting coacervation and the thermal properties of coacervates. Besides, this review describes the microencapsulation processes physicochemical properties and release characteristics of essential oils microcapsules based on complex coacervation method. Finally, the review concentrates on the antimicrobial properties and the applications of essential oils microcapsules in food and nutrition. Despite extensive research conducted on the preparation of essential oils microcapsules prepared by complex coacervation, the application of this technique in encapsulating essential oils exposed to high temperatures during processing and storage remains a current area of research. Therefore, the research consolidated in this review describes a high degree of thermal stability of essential oils microcapsules prepared with complex coacervation that is yet understood, which can be readily utilized in the food and pharmaceutical industries.

Gelation and microstructural properties of fish myofibrillar protein gels with the incorporation of l-lysine and l-arginine at low ionic strength.

BACKGROUND: The solubility limitation and poor gelation properties of myofibrillar proteins at low ionic strength are the most challenging obstacle to limit salt reduction in meat products. In the present study, five amino acids with different concentrations of 5, 10 15, and 20 mmol L-1 , l-lysine (Lys), l-arginine (Arg), l-histidine (His), l-proline (Pro) and l-glycine (Gly), were introduced into myofibrillar protein (MP) suspensions at low ionic strength to improve solubility and gelation properties. RESULTS: The dynamic rheological analysis showed that the MPs at 100 mmol L-1 NaCl containing 15/20 mmol L-1 Lys/Arg exhibited similar gelling behaviors to MPs at 600 mmol L-1 NaCl. Similarly, 15/20 mmol L-1 Lys/Arg significantly increased the solubility of MPs and the water holding capacity (WHC) and gel strength of MP gels, which was comparable to those of MPs at 600 mmol L-1 NaCl. Furthermore, Lys and Arg promoted the formation of aggregation-type gel with a dense and compact structure observed by scanning electron microscopy. The gels containing 15/20 mmol L-1 Lys/Arg exhibited a significant increase in the proportion of immobilized water (P21 ). CONCLUSION: The enhancement of WHC, gel strength, and P21 was closely associated with the increased solubility and the dense microstructure induced by Lys and Arg with high concentrations of 15 and 20 mmol L-1 . The knowledge obtained from this study may be useful for the improvement of gelation properties of MPs at low ionic strength using l-lysine and l-arginine. © 2021 Society of Chemical Industry.

Effect of sodium chloride concentration on off-flavor removal correlated to glucosinolate degradation and red radish anthocyanin stability.

Anthocyanin-rich concentrates from different red radish can be used as natural food colorants. However, the development of off-flavor during extraction has been major challenge in processing industries. This work aimed to evaluate the effect of sodium chloride (NaCl) concentration in phosphoric acidified medium pH 2.5 on removal of off-flavor from red radish anthocyanin. The effect of NaCl concentration on anthocyanin properties was also evaluated. Results showed that the total glucosinolate was highly degraded at high NaCl concentration (< 500 mM) compared with control, leading to higher off-flavor development. Additionally, the glucosinolate degradation was positively and significantly correlated to isothiocyanate, while was negatively and significantly correlated with dimethyl di-, trisulfide, cedrol, triacetin, 6-methyl-5-hepten-2-one. Moreover, total monomeric and color properties of extracted anthocyanins were degraded at high NaCl concentration (< 500 mM) compared with control. The tentative anthocyanin identification by UPLC-TQ-MS showed 12 glycosylated anthocyanins substituted at C3 and C5 in tested anthocyanin extracts. In conclusion, higher NaCl concentration (< 500 mM) could not be useful for red radish off-flavor removal and anthocyanin properties.

Effect of Temperature on Flavor Compounds and Sensory Characteristics of Maillard Reaction Products Derived from Mushroom Hydrolysate.

Maillard reaction products (MRPs) were prepared from mushroom hydrolysate (MH) by heating with d-xylose and l-cysteine at various temperatures (100 °C-140 °C) for 2 h at a pH of 7.4. The sensory characteristics of MH and MRPs were evaluated by panelists and volatile compounds were analyzed by GC/MS. Additionally, partial least squares regression (PLSR) was performed to analyze the correlation between quantitative sensory characteristics and GC/MS data. GC/MS results revealed that higher reaction temperature resulted in more nitrogen and sulfur containing compounds in MRPs while alcohols, ketones and aldehydes were the major flavor compounds obtained in MH. PLSR results showed that 3-phenylfuran and 2-octylfuran were the compounds responsible for the caramel-like flavor; 1-octen-3-ol, (E)-2-octen-1-ol and geranyl acetone were significantly and positively correlated to mushroom-like flavor, whereas, 2-thiophene-carboxaldehyde, 2,5-thiophenedicarboxaldehyde and 3-methylbutanal positively affected MRPs meat-like attribute. Overall, 125 °C was identified as the optimal temperature for preparing MRPs with abundant volatile compounds and favorable sensory characteristics; the concentration of free amino acids and 5'-GMP, which are associated with the umami taste, in MRPs derived under 125 °C were 3 to 4 times higher than those in MH.

Correlating enzymatic browning inhibition and antioxidant ability of Maillard reaction products derived from different amino acids.

BACKGROUND: Up to now, only limited research on enzymatic browning inhibition capacity (BIC) of Maillard reaction products (MRPs) has been reported and there are still no overall and systematic researches on MRPs derived from different amino acids. In the present study, BIC and antioxidant capacity, including 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and Fe2+ reducing power activity, of the MRPs derived from 12 different amino acids and three reducing sugars were investigated. RESULTS: The MRPs of cysteine (Cys), cystine, arginine (Arg) and histidine (His) showed higher BIC compared to other amino acids. Lysine (Lys)-MRPs showed the highest absorbance value at 420 nm (A420 ) but very limited BIC, whereas Cys-MRPs, showed the highest BIC and the lowest A420 . The A420 can roughly reflect the trend of BIC of MRPs from different amino acids, except Cys and Lys. MRPs from tyrosine (Tyr) showed the most potent antioxidant capacity but very limited BIC, whereas Cys-MRPs showed both higher antioxidant capacity and BIC compared to other amino acids. Partial least squares regression analysis showed positive and significant correlation between BIC and Fe2+ reducing power of MRPs from 12 amino acids with glucose or fructose, except Lys, Cys and Tyr. The suitable pH for generating efficient browning inhibition compounds varies depending on different amino acids: acidic pH was favorable for Cys, whereas neutral and alkaline pH were suitable for His and Arg, respectively. Increasing both heating temperature and time over a certain range could improve the BIC of MRPs of Cys, His and Arg, whereas any further increase deteriorates their browning inhibition efficiencies. CONCLUSION: The types of amino acid, initial pH, temperature and time of the Maillard reaction were found to greatly influence the BIC and antioxidant capacity of the resulting MRPs. There is no clear relationship between BIC and the antioxidant capacity of MRPs when reactant type and processing parameters of the Maillard reaction are considered as variables. © 2017 Society of Chemical Industry.

Analysis of the browning reaction in a sorbitol/glycine model: Formation and degradation of precursors, glucose and α-dicarbonyl compounds during heating.

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.

Microwave-induced heterogeneity in protein conformation and water mobility interferes with the distribution pattern and migration pathway of sodium ion in myofibrillar protein gel.

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.

Rapid preparation of the Amadori rearrangement product of glutamic acid - xylose through intermittent microwave heating and its browning formation potential in microwave thermal processing.

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.

Liposomes for encapsulation of liposoluble vitamins (A, D, E and K): Comparation of loading ability, storage stability and bilayer dynamics.

To understand the encapsulation difference and stability mechanism of nanoliposomes (NLPs) loaded with different kinds and loads of liposoluble vitamins (LSV, including VA, VD, VE, and VK), the physicochemical stability during three-months storage and bilayer membrane properties of LSV-NLPs were evaluated. The results suggested that VD and VE were not suitable for high-load (≥30 wt%) encapsulation, but the stability of other LSV-NLPs was excellent during storage. Their particle size was less than 100 nm, the polydispersity index was less than 0.3, and the retention rate of VE and VK remained above 85 %. LSV encapsulation inhibited malondialdehyde production, decreased liposome surface roughness, and improved nanoliposome rigidity. The order of occupying capacity of LSV to the hydrophobic zone of the bilayer was VK＞VD＞VE＞VA, and the stability of LSV located in the hydrophobic region was better. Except for high-load VD and VE, the other LSV encapsulation increased the microviscosity of the lipid-water interface and hydrophobic zone by 0.5 âˆ¼ 7.1 times and 0.5 âˆ¼ 20 times, respectively. The accumulation of acyl chain was enhanced by 0.2 âˆ¼ 4 times, and the interchain longitudinal and intra-chain transverse order degree was increased by 10.89 %∼144.35 % and 3.26 %∼115.52 %, respectively. High microviscosity and tight chain stacking limited bilayer fluidity and thus improve LSV-NLPs stability. This work will contribute to the application of nanoliposomes as liposoluble vitamin carriers in the food industry.

Effects of tannic acid interfacial absorption on the physicochemical stability of algal oil-loaded emulsions and inhibition of fishy off-flavor.

In the present study, the inhibition of fishy off-flavor and destabilization in algae oil-loaded emulsions by tannic acid (TA) adsorption on octenyl succinic anhydride (OSA) starch interfaces were investigated. The changes of typical fishy off-flavor components in the emulsion, physiochemical stability, and interaction between TA and OSA starch were analyzed. The TA fortification significantly prevented the production of fishy smell-related volatile components such as heptanal and (E, E)-3, 5-octadiene-2-one. The proportion of TA on the interface was more than 90 %, forming an interfacial film with the antioxidant function. The emulsions stabilized by OSA starch-TA complexes had better oxidative and physical stability. The isothermal titration calorimetry suggested that the interaction between OSA starch and TA included hydrogen bonding and van der Waals forces (ΔG = -13.272 kJ·mol-1·K-1, ΔH = -1.302 × 103 kJ·mol-1, ΔS = -4.326 kJ·mol-1·K-1). Altogether, these results provided application guidance for developing starch-based oil-in-water emulsion systems with antioxidant properties.

The selective encapsulation and stabilization of cinnamaldehyde and eugenol in high internal phase Pickering emulsions: Regulating the interfacial properties.

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.

Effect of tannic acid-OSA starch complexation on the binding capacity and release of aldehydes off-flavor in aqueous matrix.

In order to further clarify the regulation of tannic acid on the off-flavor in starch-based algal oil emulsions, the effect of different starch matrix (OSA starch and OSA starch-tannic acid complex) on the release capacities of aldehydes (pentanal, hexanal, heptanal, nonanal) were investigated. The adsorption and retention ability, thermodynamic parameters, and hydrophobicity of aldehydes in the starch matrix were analyzed. Nonanal exhibited the strongest adsorption ability (65.01%-85.69%) with the starch matrix, followed by heptanal, hexanal, and pentanal, which accounted for the structures of aldehydes. Furthermore, aldehydes had a higher affinity with complex (16.33%-83.67%) than OSA starch (9.70%-66.71%) because the tannic acid altered the structure of OSA starch. Isothermal titration calorimetry suggested that the interaction between the starch matrix and aldehydes was an entropy-driven spontaneous endothermic reaction, and hydrophobic interactions were the predominant driving forces. Altogether, these results lay a theoretical foundation for facilitating the regulation of flavor in starch foods.

Changes of lipid oxidation, volatile and taste-active compounds during pan-heating of pork belly.

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 â„ƒ) 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.

Microwave heating and conduction heating pork belly: Non-volatile compounds and their correlation with taste characteristics, heat transfer modes, and matrix microstructure.

This study investigated the difference in the taste characteristics of pork belly cooked by traditional pan-heating (TH), microwave heating (MH), and microwave combined with conduction heating (MH + CH). The results showed that MH destroyed the microstructure integrity and made the cooking loss (50.33%) and sodium ion concentration (10.8 mg/g) about 1.6 times that of MH + CH, thereby enhancing the saltiness. In addition, compared with TH, microwave heating could accelerate the hydrolysis of proteins and the thermal degradation of ribonucleotides, resulting in higher contents of free amino acids (880.71 and 714.85 mg/100 g) and nucleotides (181.41 and 145.52 mg/100 g) in MH and MH + CH. Combined with the results of non-volatile compounds and sensory evaluation, the MH + CH not only promoted the accumulation but also improved the dissolution uniformity of taste compounds, which enhanced the sensory umami. The inconsistency between non-volatile compounds, electronic tongue, and sensory evaluation indicated that the matrix effects caused by cooking also had significant influences on the taste quality of solid samples.

Contribution of sulfur-containing compounds to the colour-inhibiting effect and improved antioxidant activity of Maillard reaction products of soybean protein hydrolysates.

BACKGROUND: Light-coloured and savoury-tasting flavour enhancers are attractive to both consumers and food producers. The aim of this study was to investigate the colour-inhibiting effect of L-cysteine and thiamine during the Maillard reaction of soybean peptide and D-xylose. The correlation between volatile compounds and antioxidant activity of the corresponding products was also studied. RESULTS: Colour formation was markedly suppressed by cysteine. Compared with peptide/xylose (PX), the taste profile of Maillard reaction products (MRPs) derived from peptide/xylose/cysteine (PXC) and peptide/xylose/cysteine/thiamine (PXCT) was stronger, including umami, mouthfulness, continuity, meaty and overall acceptance. PXC and PXCT also exihibited distinctly higher antioxidant activity. Principal component analysis was applied to investigate the correlation between antioxidant activity and volatile compounds. Of 88 volatile compounds identified, 55 were significantly correlated with antioxidant activity by two principal components (accounting for 85.05% of the total variance). CONCLUSION: Effective colour control of the Maillard reaction by L-cysteine may allow the production of healthier (higher antioxidant activity) and tastier foods to satisfy consumers' and food producers' demands. Light-coloured products might be used as functional flavour enhancers in various food systems.

Saltiness perception enhancement of fish meat treated by microwave: The significance of conformational characteristics, water and sodium mobility.

A saltiness perception enhancement method of grass carp meat conducted by microwave heating was investigated. Ion chromatographic results demonstrated that all samples had the same sodium level retained in matrices after being treated by water bath (WBV) and microwave with different power of 2.5, 7.5, 10, and 12.5 W/g (MWV). However, the meat treated by microwave exhibited a higher salty intensity than that of WBV, particularly MWV-10 W/g and MWV-12.5 W/g. The enhanced saltiness perception of meat treated by microwave was attributed to the facilitated water and sodium mobility demonstrated by low field-NMR and pulse-field-gradient stimulated echo (PFG-STE) 23Na NMR experiments. Furthermore, the enhancement was also related to the formation of microstructure favorable for sodium diffusion, originating from the insufficient denaturation and less exposure of hydrophobic groups of proteins induced by microwave heating. Therefore, microwave heating has the potential to enhance the saltiness perception of meat in the food industry.

High internal phase pickering emulsions stabilized by pea protein isolate-high methoxyl pectin-EGCG complex: Interfacial properties and microstructure.

The pea protein isolate-high methoxyl pectin-epigallocatechin gallate (PPI-HMP-EGCG) complex was used to stabilize Pickering emulsions (PEs) and high internal phase PEs (HIPPEs), and the effect of interfacial rheology on the microstructure, bulk rheology and stability of these emulsions was investigated. The PPI-HMP-EGCG complex with PPI to EGCG 30:1 exhibited partial wettability (81.6 ± 0.4°) and optimal viscoelasticity for the formation of stable interfacial layer. The microstructure demonstrated that the PPI-HMP-EGCG complex acted as an interfacial layer and surrounded the oil droplets, and continuous phases were mainly filled with excessive HMP, which enhanced emulsion stability. The formation of a firm gel-like network structure required a dense interfacial layer to provide the PEs (complex concentration of 0.1%) and HIPPEs (oil-phase up to 0.83) with ideal viscoelasticity and stability. The results provide the guidelines for the rational design of EGCG-loaded HIPPEs stabilized by water-soluble protein/polysaccharide complexes.

Chitosan decoration improves the rapid and long-term antibacterial activities of cinnamaldehyde-loaded liposomes.

In this work, cinnamaldehyde-loaded liposomes decorated with different concentrations of chitosan (0, 0.25, 0.5, 1, 2, 3, and 4 mg/mL) were prepared and their physical and antibacterial properties were evaluated. The results showed that the physical decoration of chitosan improved the encapsulation efficiency and storage stability of the liposomes. Liposomes decorated with chitosan at the concentration of 0.25 to 4 mg/mL were able to achieve an obvious antibacterial efficiency against Staphylococcus aureus after only 10 min of incubation. The antibacterial efficiency of chitosan-decorated liposomes was still higher than 90% after being stored for 28 d when the chitosan concentration was greater than 1 mg/mL. Besides, increasing the chitosan concentration significantly decreased the minimum inhibitory concentration of the liposomes. The comparison of the antibacterial activities and mechanisms of cinnamaldehyde-loaded liposomes decorated with chitosan at a concentration of 4 mg/mL (CH-CL), cinnamaldehyde-loaded liposomes (CL), cinnamaldehyde, and chitosan revealed that chitosan and cinnamaldehyde exerted a cumulative and synergistic bacteriostatic effect in the liposomes. This led to damage to the cell membrane integrity, causing cell death by inducing leakage of intracellular components. These results can potentially provide guidance for the preparation and application of natural preservatives with rapid and long-term bacteriostatic effects.

Regulating water binding capacity and improving porous carbohydrate matrix's humectant and moisture proof functions by mixture of sucrose ester and Polygonatum sibiricum polysaccharide.

The moisture stability of tobacco shred, a typical porous carbohydrate material, is very important during its processing, storage and smoking, moreover, it is sensitive to environmental conditions. Therefore, effect of sucrose esters (SEs) and sucrose ester/Polygonatum sibiricum polysaccharide mixture (SPMs) on the moisture retention and moisture resistance of tobacco shred was assessed. When SEs were added to tobacco shred, moisture resistance was significantly enhanced, whereas moisture holding capacity was attenuated. Contrarily, the addition of SPMs made moisture retention index (MRI) and moisture proof index (MPI) increase from 1.8910 to 2.1612 and from 1.9489 to 2.0665, respectively, revealing that SPMs improved the moisture retention and moisture proof ability of tobacco shred simultaneously. The monolayer moisture content (M0) was decreased by SEs and increased by SPMs. Low-field nuclear magnetic resonance (LF-NMR) analysis showed that during adsorption, SPMs reduced the interaction between tobacco shred and water via hydrophobic property of SEs; during desorption, SPMs promoted the interaction between tobacco shred and water through hydrophilic binding of polysaccharide, leading to the migration of immobilized water to bound state. The modeling of the isotherms and LF-NMR analysis clarified the mechanism why SPMs could improve moisture stability of tobacco.