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Abstract: O-Lauroyl l-serinamide and O-lauroyl l-threoninamide were synthesized with an immobilized lipase using lauric acid and l-serinamide or l-threoninamide in water-miscible organic solvents, of which 2-methyl-2-propanol gave the highest conversion of 93% for O-lauroyl l-serinamide at 50mmol-l-serinamide/L and 100mmol-lauric acid/L. The addition of 4Å 1/16 molecular sieves at 50mg/mL increased the conversion to 53% for O-lauroyl l-threoninamide at 50 mmol-l-threoninamide/L and 150mmol-lauric acid/L in 2-methyl-2-butanol. The difference of conversion between the two products was exactly proportional to the difference of solubility of aminoacid amides. [Copyright &y& Elsevier]

[Display omitted] • 1. Microwave intermittent heating can effectively regulate the Maillard reaction process. • 2. The rapid preparation of the Amadori compound (ARP) was realized by microwave heating. • 3. Dehydration rate and microwave effects were key factors to improve the yield of ARP. • 4. ARP can degrade rapidly and accelerate the Maillard reaction in microwave processing. • 5. ARP was expected to be an important color enhancer for microwave fast processed food. 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. [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] • 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]

[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]

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, TM 1 -TM 6 ) on chicken broth sensory evaluation and flavor profile was studied. Sensory evaluation results showed that chicken broth processed using TM 1 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 TM 1 samples had the most abundant odorants. The umami-taste components from TM 1 samples such as umami free amino acids and inosine 5′-monophosphate (IMP) had the highest amount, 20.0 ± 0.10 mg/g chicken broth and 17.19 ± 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Maillard reaction intermediates prepared by vacuum drying showed taste enhancement. • Reaction of small peptides with glucose led to a decline in taste enhancement. • Fluorescence spectroscopy was a practical means to characterize browning precursors. 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. [ABSTRACT FROM AUTHOR]

Maillard reaction products (MRPs) were prepared from sunflower peptide and D-xylose with or without L-cysteine (PXC or PX) by heating over a range of temperatures (80–140°C) for 2.0h and a pH of 7.4 and subsequently the products were sensory evaluated. Partial least square regression (PLSR) was performed to analyze the correlation among data of quantitative sensory descriptive analysis, peptides, GC–MS and free amino acid (FAA) data of PXCs and PXs. Results revealed that MRPs formed at 120°C with cysteine addition (PXC-120) had greater meat-like flavor, mouthfulness and continuity taste compared to other MRPs. Molecular weight distribution showed that the presence of cysteine inhibited the low molecular weight (LMW) peptide cross-linking but accelerated the high molecular weight (HMW) peptide degradation with increasing temperature. Furthermore, results showed that the peptide above 5kDa has a significant negative contribution to sensory attributes of PXCs, while the peptide between 1 and 5kDa showed no significant but positive influence on PX sensory attributes. Sulfur containing compounds showed a significant and positive correlation to sensory attributes of PXCs while nitrogen containing compounds and furan were significantly but negatively correlated to sensory attributes of PXCs. [ABSTRACT FROM AUTHOR]

Abstract: Sensory attributes and antioxidant capacity of Maillard reaction products (MRPs) from sunflower protein hydrolysate, xylose and l-cysteine model system (SFPC) were evaluated and compared to soybean MRPs (SPC). The model systems were heated at 120°C for 2.0h. Findings showed that SFPC exhibited stronger (p <0.001) antioxidant effect. The reducing power and DPPH radical scavenging activity were higher compared to SPC (0.689 vs. 0.667 at 3mg/mL and 95.06% vs.90.73% at 1mg/mL, respectively). Furthermore, the sensory attributes showed that SFPC had greater mouthfulness and continuity taste compared to SPC due to the higher content in Maillard peptide between 1 and 5kDa (18.05% vs. 16.01%), and also an acceptable meat-like flavor from sulfur substituted furan and good overall acceptability. Therefore, sunflower MRPs could potentially be used to produce flavor enhancers with high antioxidant activity as an alternative to soybean MRPs. [Copyright &y& Elsevier]

[Display omitted] • Double emulsion prior to complex coacervation was effective for co-encapsulation. • Mononuclear ellipse-like shape was obtained at 2% total biopolymer concentration. • Structural similarity of conjugated linoleic acid and PGPR damaged co-encapsulation. • The capsules made by conjugated linoleic acid has worst encapsulation of vitamin C. • Quercetin carried by conjugated linoleic acid and fish oil got better encapsulation. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spray drying improved Amadori compound conversion from 3.6% to 69.2%. • 20% salt reduction did not lower saltiness at Amadori compound dosages above 0.4%. • Proline derived Amadori compound promoted aldosterone secretion in saliva. Amadori rearrangement product (ARP) derived from proline and glucose was prepared in aqueous medium, and purified by ion exchange chromatography and identified by mass spectrometry and nuclear magnetic resonance spectrometry. The ARP was confirmed as 1-deoxy-1-L-proline-D-fructose (C 11 H 19 O 7 N, 277 Da) with four main isomers. A preliminary vacuum dehydration coupled with subsequent spray drying was used to improve the yield of ARP conversion from 3.63% to 69.15%. Furthermore, the taste characteristics of spray dried ARP products were analyzed by electronic tongue and sensory evaluation. The results indicated that when the dosage of ARP products was above 0.4%, a 20% salt reduction could be achieved without reduction in the salty taste as well as having a significant enhancement in the umami attribute. The products at low- and medium- extents of reaction could stimulate more secretion of aldosterone in oral cavity and then improve its sensitivity to the salt, while the product at high- extent of reaction inhibits aldosterone secretion. [ABSTRACT FROM AUTHOR]

• Variable-temperature Maillard reaction could indicate MRIs formation. • Maillard reaction could lower the bitterness of pea protein hydrolysates. • MRIs of pea protein hydrolysates had greater umami-enhancing abilities. • MRIs of pea protein hydrolysates showed saltiness enhancement in salt solutions. • MRIs of pea protein hydrolysates promoted salivary aldosterone secretion. Maillard reaction intermediates (MRIs) derived from enzymatic hydrolysates of pea protein, mainly initial Maillard reaction products, were prepared at a low temperature (80 °C) and the reaction time was determined by variable-temperature Maillard reaction. Electronic tongue and sensory evaluation were used to analyze the taste qualities of pea protein hydrolysates and their MRIs. Both evaluations showed that bitterness of enzymatic hydrolysates of pea protein reduced but umami taste increased through Maillard reaction. The intensities of umami and saltiness were positively correlated with the concentration of MRIs. Even when the dosage of MRIs was 0.1% (w/w), MRIs could achieve a 20% reduction in NaCl content without decreasing saltiness, which could be great potential substitutes for salt reduction. On the other hand, the increased MRIs promoted aldosterone secretion in saliva, which might enhance human perception of saltiness. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of microwave and traditional water bath on physical and chemical properties of grass carp meat and the impact on saltiness perception. The surface hydrophobicity and Fourier transform infrared spectroscopy (FTIR) results showed that microwave made meat proteins unfold less than water bath. The low degree of protein unfolding of meat cooked by microwave caused the changes in water distribution and the formation of a compact microstructure, which were related to the enhancement of saltiness perception. Furthermore, the meat cooked by microwave had lower cooking loss and shear force compared to traditional water bath. The sodium level remained and the distribution of Na and Cl in meat matrix further demonstrated sensory analysis result that the grass carp meat cooked by microwave was saltier than that cooked by water bath. The current research also provided a new approach to reduce salt consumption in fish cooking for home cooking or food industry. Unlabelled Image • Microwave cooking could improve saltiness perception of grass carp meat. • Salt retention in meat was related to water distribution and microstructure. • Water distribution differences was due to changes of protein tertiary structure. • Microstructure differences was caused by changes of protein tertiary structure. [ABSTRACT FROM AUTHOR]