Contribution of process-induced molten-globule state formation in duck liver protein to the enhanced binding ability of (E,E)-2,4-heptadienal

Contribution of ultrasound-assisted protein structural changes in marinated beef to the improved binding ability of spices and flavor enhancement

BACKGROUND

Marination is an important part of air-dried beef processing, and traditional methods are inefficient and produce inconsistent results. Ultrasound, as a novel technology, can be combined with traditional marination methods. The study aimed to investigate the improvement of beef flavor by ultrasound-assisted marination. At the same time, the potential relationship between the alteration of meat protein and flavor quality by ultrasound-assisted marinating was further investigated to enable better flavor modulation and research.

RESULTS

Headspace solid-phase microextraction-gas chromatography-mass spectrometry revealed that the spice flavor of beef was significantly enhanced by 500 W ultrasound-assisted marination. Meanwhile, the experimental results demonstrated that the ultrasound-assisted marination promoted the unfolding of beef myofibrillar protein structure, which increased the number of hydrophobic and hydrogen bonding sites, enhanced the electrostatic effect and improved the functional properties of the protein. Ultrasound-assisted marination significantly enhanced the binding ability of beef myofibrillar proteins to flavor compounds compared with conventional marination. An electronic nose confirmed that this resulted in a significant increase in the flavor of the marinated meat.

CONCLUSION

Ultrasound-assisted marination effectively enhanced the flavor of marinated meat, which was closely related to the development of protein conformation. The results of this study have important implications for the food industry and the role of protein unfolding processes in flavor modulation. In particular, the findings can be practically applied to improving meat flavor under ultrasound-assisted marination. © 2024 Society of Chemical Industry.

Molten globule-state protein structure: Perspectives from food processing applications

Under specific pretreatment or processing conditions, spheroprotein can be transformed into a molten globule state, a typical protein conformation with enhanced functionality. Analyzing the correlation between the formation of molten-globule structures and their quality and functional characteristics is critical for developing tailored processing features, especially for minimally processed future foods. This review outlines the mechanisms driving the formation of molten globule proteins through various processes including ultra-high pressure pretreatments, heating, ultrasonication, pH-shifting, macromolecular crowding and exposure to small-molecule denaturants. These treatments yield proteins that retain structural compactness and primary and secondary structures of their native forms, but with modified conformations and increased hydrophobicity. Common methods for characterizing molten globule proteins include fluorescence spectroscopy, circular dichroism spectroscopy, and nuclear magnetic resonance. The review also explores the application of molten globule proteins in food processing, highlighting their potential significance in advancing the field. The detailed elucidation and exploration of the microstructural transition and conformational features of molten globule proteins, together with their quantitative relationship with processibility of proteins from various sources, holds significant implications for optimizing protein-based food processing techniques and achieving targeted improvements in food quality.

Carboxymethyl chitosan coating infused with linalool-loaded molten globular β-Lactoglobulin nanoparticles for extended preservation of fresh-cut apples

This investigation employed molten globule state β-lactoglobulin nanoparticles (MG-BLGNPs) for encapsulating linalool (LN) combined with carboxymethyl chitosan (CMC) coating to enhance the shelf-life of fresh-cut apples. The effect of different MG structures on the encapsulation efficiency of BLGNPs and the properties of coating was studied. Structural characterization and molecular simulation showed structural differences between heat-induced MG state (70-BLGNPs, heated at 70 °C for 1 h) and sodium dodecyl sulfate-co-heat-induced MG state (SDS/70-BLGNPs, treated with 0.192 mg/mL SDS for 10 min, then heated at 70 °C for 1 h), with the latter being more unfolded. LN self-assembles into MG-BLGNPs, among the generated particles, SDS/70-BLG@LN exhibits stronger binding effect and higher LN loading capacity. Integration of MG-BLG@LN into CMC enhanced coating's mechanical properties and adhesion to fresh-cut apples. The SDS/70-BLG@LN/CMC coating showed superior preservation on fresh-cut apples during storage, reducing enzymatic browning, membrane lipid oxidation, and microbial growth while maintaining hardness and overall quality.

Exploring the binding mechanisms of thermally and ultrasonically induced molten globule-like β-lactoglobulin with heptanal as revealed by multi-spectroscopic techniques and molecular simulation

This work employed the model protein β-lactoglobulin (BLG) to investigate the contribution of microstructural changes to regulating the interaction patterns between protein and flavor compounds through employing computer simulation and multi-spectroscopic techniques. The formation of molten globule (MG) state-like protein during the conformational evolution of BLG, in response to ultrasonic (UC) and heat (HT) treatments, was revealed through multi-spectroscopic characterization. Differential MG structures were distinguished by variations in surface hydrophobicity and the microenvironment of tryptophan residues. Fluorescence quenching measurements indicated that the formation of MG enhanced the binding affinity of heptanal to protein. LC-MS/MS and NMR revealed the covalent bonding between heptanal and BLG formed by Michael addition and Schiff-base reactions, and MG-like BLG exhibited fewer chemical shift residues. Molecular docking and molecular dynamics simulation confirmed the synergistic involvement of hydrophobic interactions and hydrogen bonds in shaping BLG-heptanal complexes thus promoting the stability of BLG structures. These findings indicated that the production of BLG-heptanal complexes was driven synergistically by non-covalent and covalent bonds, and their interaction processes were influenced by processes-induced formation of MG potentially tuning the release and retention behaviors of flavor compounds.

Food off-odor generation, characterization and recent advances in novel mitigation strategies

The pronounced perception of off-odors poses a prevalent issue across various categories of food ingredients and processed products, significantly exerting negative effects on the overall quality, processability, and consumer acceptability of both food items and raw materials. Conventional methods such as brining, marinating, and baking, are the main approaches to remove the fishy odor. Although these methods have shown notable efficacy, there are simultaneously inherent drawbacks that ultimately diminish the processability of raw materials, encompassing alterations in the original flavor profiles, the potential generation of harmful substances, restricted application scopes, and the promotion of excessive protein/lipid oxidation. In response to these challenges, recent endeavors have sought to explore innovative deodorization techniques, including emerging physical processing approaches, the development of high-efficiency adsorbent material, biological fermentation methods, and ozone water rinsing. However, the specific mechanisms underpinning the efficacy of these deodorization techniques remain not fully elucidated. This chapter covers the composition of major odor-causing substances in food, the methodologies for their detection, the mechanisms governing their formation, and the ongoing development of deodorization techniques associated with the comparison of their advantages, disadvantages, and application mechanisms. The objective of this chapter is to furnish a theoretical framework for enhancing deodorization efficiency through fostering the development of suitable deodorization technologies in the future.

Correlation investigation between core microbe inoculation and the evolution of flavor characteristics during the storage of sturgeon caviar (Acipenser gueldenstaedtii)

The volatile and non-volatile compounds were monitored to investigate the microbial evolution associated with the characteristic flavors for sturgeon caviar during refrigeration. The results revealed that the composition of volatile compounds changed significantly with prolonged refrigeration time, especially hexanal, nonanal, phenylacetaldehyde, 3-methyl butyraldehyde, and 1-octen-3-ol. The nonvolatile metabolites were mainly represented by the increase of bitter amino acids (Thr. Ser, Gly, Ala, and Pro) and a decrease in polyunsaturated fatty acids, especially an 18.63 % decrease in 5 months of storage. A total of 332 differential metabolites were mainly involved in the biosynthetic metabolic pathways of α-linolenic acid, linoleic acid, and arachidonic acid. The precursors associated with flavor evolution were mainly phospholipids, including oleic, linoleic, arachidonic, eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids. The most abundant at the genus level was Serratia, followed by Arsenophnus, Rhodococcus, and Pseudomonas, as obtained by high-throughput sequencing. Furthermore, seven core microorganisms were isolated and characterized from refrigerated caviar. Among them, inoculation with Mammalian coccus and Bacillus chrysosporium restored the flavor profile of caviar and enhanced the content of nonvolatile precursors, contributing to the characteristic aroma attributes of sturgeon caviar. The study presents a theoretical basis for the exploitation of technologies for quality stabilization and control of sturgeon caviar during storage.

Tunability of Pickering particle features of whey protein isolate via remodeling partial unfolding during ultrasonication-assisted complexation with chitosan/chitooligosaccharide

The potential of ultrasonication-driven molecular self-assembly of whey protein isolate (WPI) with chitosan (CS)/chitooligosaccharide (COS) to stabilize Pickering emulsions was examined, based on CS/COS ligands-induced partial unfolding in remodeling the Pickering particles features. Multi-spectral analysis suggested obvious changes in conformational structures of WPI due to interaction with CS/COS, with significantly higher unfolding degrees of WPI induced by COS. Non-covalent interactions were identified as the major forces for WPI-CS/COS conjugates. Ultrasonication enhanced electrostatic interaction between CS's -NH3 groups and WPI's -COO- groups which improved emulsification activity and storability of WPI-COS stabilized Pickering emulsion. This was attributed to increased surface hydrophobicity and decreased particle size compared to WPI-CS associated with differential unfolding degrees induced by different saccharide ligands. CLSM and SEM consistently observed smaller emulsion droplets in WPI-COS complexes than WPI-CS/COS particles tightly adsorbed at the oil-water interface. The electrostatic self-assembly of WPI with CS/COS greatly enhanced the encapsulation efficiency of quercetin than those stabilized by WPI alone and ultrasound further improved encapsulation efficiency. This corresponded well with the quantitative affinity parameters between quercetin and WPI-CS/COS complexes. This investigation revealed the great potential of glycan ligands-induced conformational transitions of extrinsic physical disruption in tuning Pickering particle features.

Identification of Efficacy-Associated Markers to Discriminate Flos Chrysanthemum and Flos Chrysanthemi Indici Based on Fingerprint-Activity Relationship Modeling: A Combined Evaluation over Chemical Consistence and Quality Consistence

Monitoring the quality consistency of traditional Chinese medicines, or herbal medicines (HMs), is the basis of assuring the efficacy and safety of HMs during clinical applications. The purpose of this work was to characterize the difference in hydrophilic antioxidants and related bioactivities between Flos Chrysanthemum (JH) and its wild relatives (Chrysanthemum indicum L.; YJH) based on the establishment of fingerprint-efficacy relationship modeling. The concentrations of the total phenolics and flavonoids of JH samples were shown to be generally higher than those of YJH, but the concentration distribution ranges of YJH were significantly greater compared to JH samples, possibly related to environmental stress factors leading to the concentration fluctuations of phytochemicals during the growth and flowering of Chrysanthemum cultivars. Correspondingly, the total antioxidant capabilities of JH were greatly higher than those of YJH samples, as revealed by chemical assays, including DPPH and ABTS radical scavenging activities and FRAP assays. In addition, cellular-based antioxidant activities confirmed the results of chemical assays, suggesting that the differences in antioxidant activities among the different types of Chrysanthemums were obvious. The extracts from YJH and JH samples showed significant α-glucosidase inhibitory activity and lipase-inhibitory activity, implying the modulatory effects on lipid and glucose metabolisms, which were also confirmed by an untargeted cell-based metabolomics approach. The selected common peaks by similarity analysis contributed to the discrimination of YJH and JH samples, and the modeling of the fingerprint-bioactivity relationship identified neochlorogenic acid, isochlorogenic acid A, and linarin as efficacy-associated chemical markers. These results have demonstrated that integrating HPLC fingerprints and the analysis of similarity indexes coupled with antioxidant activities and enzyme-inhibitory activities provides a rapid and effective approach to monitoring the quality consistency of YJH/JH samples.