Co-encapsulation of L-ascorbic acid and quercetin by gelatin/sodium carboxymethyl cellulose coacervates using different interlayer oils.

A two-step emulsification prior to complex coacervation was employed to develop a co-encapsulation technology of hydrophilic and hydrophobic components for nutrition enhancement. Processing parameters of mononuclear ellipse-like microcapsules using gelatin and sodium carboxymethyl cellulose as wall materials were evaluated. The particle size and morphology of microcapsules and the encapsulation efficiency of L-ascorbic acid were significantly affected by the water-oil phase ratio and total biopolymer concentration. The L-ascorbic acid and quercetin co-encapsulated microcapsules with an average size of 65.26 µm showed good physical and chemical stability. The encapsulation efficiencies of L-ascorbic acid and quercetin were 69.91% and 88.21%, respectively. To predict the potential of functional lipids as hydrophobic carriers, microcapsules using soybean oil, olive oil, fish oil, and conjugated linoleic acid as interlayer oils were developed. The encapsulation efficiencies of hydrophobic compounds carried by different oils were similarly high (88.21-93.08%), whereas, hydrophilic ones carried by conjugated linoleic acid had the lowest encapsulation efficiency (32.54%). The interface tension results indicated that the interfacial stability was impaired by a competitive relation between conjugated linoleic acid and hydrophobic emulsifier at the interface, due to their structural similarity. These results provided the guidance for improving the quality of interlayer oils from microcapsules.

Mild Enzyme-Induced Gelation Method for Nanoparticle Stabilization: Effect of Transglutaminase and Laccase Cross-Linking.

Low-environment-sensitive nanoparticles were prepared by enzymatic cross-linking of electrostatic complexes of dextran-grafted whey protein isolate (WPI-Dextran) and chondroitin sulfate (ChS). The effect of transglutaminase (TG) and laccase cross-linking on nanoparticle stability was investigated. Covalent TG cross-linking and grafted dextran cooperatively contributed to the stability of nanoparticles against dissociation and aggregation under various harsh environmental conditions (sharply varying pH, high ionic strength, high temperature, and their combined effects). However, fragmentation induced by laccase treatment did not promote nanoparticle stability. Structural characterization showed that the compact structure promoted by TG-induced covalent isopeptide bonds repressed dissociation against varying environmental conditions and thermal-induced aggregation. Furthermore, the increasing α-helix and decreasing random coil contents benefited the formation of disulfide bonds, further contributing to the enhanced stability of nanoparticles cross-linked by TG, whereas weak hydrophobic interactions and hydrogen bonding as evidenced by the increase in ß-sheet and microenvironmental changes were not able to maintain the stability of nanoparticles treated with laccase. Encapsulated cinnamaldehyde presented sustained release from TG-cross-linked nanoparticles, and the bioaccessibility was considerably enhanced to 50.7%. This research developed a novel mild strategy to enhance nanoparticle stability in harsh environments and digestive conditions, which could be an effective delivery vehicle for hydrophobic nutrients and drug applications in food and pharmaceutical industries.

Contribution of tobacco composition compounds to characteristic aroma of Chinese faint-scent cigarettes through chromatography analysis and partial least squares regression.

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.

Improved controlled flavor formation during heat-treatment with a stable Maillard reaction intermediate derived from xylose-phenylalanine.

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 (Dh) 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 A294 of the solution increased slightly yet A420 remained stable. Numerous flavor compounds in MRPs decreased during heat treatment, meanwhile the cross-linking and aggregation of MRPs were intensified, and the particles' Dh 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.

Synergistic Effect of a Thermal Reaction and Vacuum Dehydration on Improving Xylose-Phenylalanine Conversion to N-(1-Deoxy-d-xylulos-1-yl)-phenylalanine during an Aqueous Maillard Reaction.

The synergistic effect of a thermal reaction and vacuum dehydration on the conversion of xylose (Xyl) and phenylalanine (Phe) to a Maillard-reaction intermediate (MRI) was researched. The yield of N-(1-deoxy-α-d-xylulos-1-yl)-phenylalanine was successfully improved and increased from 13.62 to 47.23% through the method combining a thermal reaction and vacuum dehydration. A dynamic process was involved in the transformation of Xyl and Phe (Xyl-Phe) to N-substituted d-xylosamine and in the transformation of N-substituted d-xylosamine to N-(1-deoxy-α-d-xylulos-1-yl)-phenylalanine during the initial stage of dehydration; then, only the transformation of N-substituted d-xylosamine to N-(1-deoxy-α-d-xylulos-1-yl)-phenylalanine occurred during the final stage. Furthermore, the MRI was prepared under optimized conditions (90 °C and pH 7.4), and the obtained MRI was characterized and confirmed by ESI mass spectrometry and NMR.

Characterization of odor-active compounds of chicken broth and improved flavor by thermal modulation in electrical stewpots.

The influence of high temperature modes (cooking in traditional clay stewpot (TS) and cooking in commercial ceramic electrical stewpot (CS)) and low temperature modes (cooking in electrical stewpot with Temperature Modulations, TM1-TM6) on chicken broth sensory evaluation and flavor profile was studied. Sensory evaluation results showed that chicken broth processed using TM1 had the best flavor with higher chicken meat-like and lower off-flavor scores. Gas chromatography-mass spectrometry (GC-MS) and GC-MS/olfactometry (GC-MS/O) results revealed that the TM1 samples had the most abundant odorants. The umami-taste components from TM1 samples such as umami free amino acids and inosine 5'-monophosphate (IMP) had the highest amount, 20.0 ±â€¯0.10 mg/g chicken broth and 17.19 ±â€¯0.58 µg/g chicken broth respectively. The relationship between sensory evaluation and odor-active compounds were evaluated by Partial Least Squares Regression (PLSR), and the PLSR analysis indicated that heptanal, benzaldehyde, (Z)-2-decenal, (E,E)-2,4-decadienal, 1-pentanol, 2-undecanone, 2-pentyl-furan and one unknown compound were significantly and positively correlated with chicken meat-like note. Whereas, fatty aroma were significantly and positively correlated with octanal, (E,E)-2,4-decadienal and 1-pentanol. (E,E)-2,4-Decadienal and 2-undecanone had a significant and negative correlation with off-flavor attribute.

Sodium sulfite pH-buffering effect for improved xylose-phenylalanine conversion to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine during an aqueous Maillard reaction.

The yield of the Maillard reaction intermediate (MRI), prepared in aqueous medium, is usually unsatisfactory. However, the addition of sodium sulfite could improve the conversion of xylose-phenylalanine (Xyl-Phe) to the MRI (N-(1-deoxy-d-xylulos-1-yl)-phenylalanine) in aqueous medium. Sodium sulfite (Na2SO3) showed a significant pH-buffering effect during the Maillard reaction, which accounted for its facilitation of the N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. The results revealed that the pH could be maintained at a relatively high level (above 7.0) for an optimized pH-buffering effect when Na2SO3 (4.0%) was added before the reaction of Xyl-Phe. Thus, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine increased from 47.23% to 74.86%. Furthermore, the addition moment of Na2SO3 and corresponding solution pH were crucial factors in regulating the pH-buffering effect of Na2SO3 on N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. Based on the pH-buffering effect of Na2SO3 and maintaining the optimal pH 7.4 relatively stable, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine was successfully improved.

Investigating the optimum conditions for minimized 3-chloropropane-1,2-diol esters content and improved sensory attributes during savory beef flavor preparation.

In this study, the effects of enzymatic hydrolysis of tallow and addition of sodium chloride (NaCl) were evaluated on the formation of 3-monochloropropane-1,2-diol (3-MCPD) esters and sensory characteristic of beef flavors. The enzymatic hydrolysis condition had significant effects on 3-MCPD mono/di-esters formation during the beef flavor preparation. Considering the safety and sensory characteristics of beef flavors, the optimal enzymatic hydrolysis conditions were selected as: lipase concentration 75U/g tallow, tallow concentration 80% (w/v) and pH 7.0 at 47.5°C for 9.5h. Using the optimal enzymatic hydrolysis conditions, no 3-MCPD monoesters were detected and 3-MCPD-diesters concentration was strongly dependent on NaCl concentration and its addition moment (before or after thermal reaction) at different temperatures. In conclusion, beef flavor was prepared using the optimal hydrolysis conditions and heated at 110°C for 100min, then 10% NaCl was added when the system was cooled to 60°C.

Preparation and characterization of magnetic molecularly imprinted polymers for the extraction of hexamethylenetetramine in milk samples.

Magnetic molecularly imprinted polymers (M-MIPs) were synthesized as the sorbents for extracting hexamethylenetetramine (HMT) from milk samples. Molecular simulations were used to calculate the interaction energies of the template monomers. The physical properties of M-MIPs were characterized. The adsorption isotherms and kinetics were investigated. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was applied to determine the amount of HMT residue in milk samples. In the optimized method, a linear calibration curve was obtained using a matrix-matched standard in the range of 1.0-50.0µgL-1. The limit of detection (LOD) and limit of quantification (LOQ) was 0.3µgkg-1 and 1.0µgkg-1, respectively. The relative standard deviation (RSD) of the intra-day assay ranged from 2.6% to 5.2%, while that of the inter-day assay ranged from 3.6% to 11.5%. The recovery of HMT in milk samples ranged from 88.7% to 111.4%.

Contribution of crosslinking products in the flavour enhancer processing: the new concept of Maillard peptide in sensory characteristics of Maillard reaction systems.

In this study, the flavour-enhancing properties of the Maillard reaction products (MRPs) for different systems consisted of different peptides (sunflower, SFP; corn, CP and soyabean SP) with, xylose and cysteine were investigated. Maillard systems from peptides of sunflower, corn and soyabean with xylose and cysteine were designated as PXC, MCP and MSP, respectively. The Maillard systems were prepared at pH of 7.4 using temperature of 120C for 2 h. Results showed that all systems were significantly different in all sensory attributes. The highest scores for mouthfulness and continuity were observed for MCP with the lowest peptides distribution between 1000 and 5000 Da, known as Maillard peptide. This revealed that the MCP with the lowest Maillard peptide content had the strongest "Kokumi" effect compared to the other MRPsand demonstrated that "kokumi effect" of MRPs was contributed by not only the "Maillard peptide" defined by the molecular weight (1000-5000 Da). Results on sensory evaluation after fractionation of PXC followed by enzymatic hydrolysis showed no significant differences between PXC, P-PXC and their hydrolysates. This observation therefore confirmed that the presence of other contributors attributed to the "Kokumi" effect rather than the Maillard peptide. It can be deduced that the unhydrolyzed crosslinking products might have contributed to the "Kokumi" effect of MRPs. The structures of four probable crosslinking compounds were proposed and the findings have provided new insights in the sensory characteristics of xylose, cysteine and sunflower peptide MRPs.