Recent Progress on Green New Phase Extraction and Preparation of Polyphenols in Edible Oil.

With the proposal of replacing toxic solvents with non-toxic solvents in the concept of green chemistry, the development and utilization of new green extraction techniques have become a research hotspot. Phenolic compounds in edible oils have good antioxidant activity, but due to their low content and complex matrix, it is difficult to achieve a high extraction rate in a green and efficient way. This paper reviews the current research status of novel extraction materials in solid-phase extraction, including carbon nanotubes, graphene and metal-organic frameworks, as well as the application of green chemical materials in liquid-phase extraction, including deep eutectic solvents, ionic liquids, supercritical fluids and supramolecular solvents. The aim is to provide a more specific reference for realizing the green and efficient extraction of polyphenolic compounds from edible oils, as well as another possibility for the future research trend of green extraction technology.

Effects of polyphenols on the gel and digestive properties of Penaeus vannamei myosin after freezing.

Polyphenols could inhibit the freezing-induced denaturation of myosin, and affect its nutritional and functional properties, which have rarely been studied to date. Therefore, the effects of interactions between polyphenols and myosin after freezing on myosin gel and digestive properties were investigated using low field NMR, a texture analyzer, a dynamic rheometer, ultraviolet-visible spectra, scanning electron microscopy, LC-MS/MS, an automatic amino acid analyzer, etc. Hesperetin (HE), dihydroquercetin (DI), salidroside (SA), and mangiferin (MA) increased the water-holding capacity, non-flowable water content, gel strength, texture, storage modulus, and fractal dimensions of the myosin gel, while modifying its leading force. The results of scanning electron microscopy revealed that the surfaces of polyphenol groups were relatively smoother than those of the control group. Meanwhile, the four types of polyphenols under study significantly improved the gastric and gastrointestinal digestibility of myosin. Furthermore, they significantly increased the contents of essential, flavor, and total free amino acids, as well as the unique peptide numbers in myosin digestion products. This work provides reliable guidance for polyphenols to improve protein function and nutritional properties.

Synergistic effect of ultrahigh pressure and allicin on gel properties, flavor characteristics, and myosin structure of the obturator muscle of the scallop (Patinopecten yessoensis).

The synergistic effects of the combination of ultrahigh pressure (UHP) with allicin on the gel properties, flavor characteristics, and myosin structure of scallops were investigated. The results indicated that chewiness reached maximum, uniform, and dense microstructures at B-300 MPa, and scallops with favorable gel properties. In addition, the electronic nose and tongue could clearly distinguish the olfactory and gustatory properties of scallops, and the interaction of UHP and allicin increased the variety of volatile compounds in scallops, which mainly included 1-hydroxy-2-propanone, 1-hexenal, 2-butanone-D, and 1-octen-3-ol. The main performance was fruit aroma and a plantlike aroma and mushroomlike odor. UHP and allicin changed the microenvironment of tryptophan residues, and allicin formed larger aggregates by forming disulfides with myosin. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis results could show that myosin had low degradation in B-300 MPa. Thus, comprehensively viewed, UHP and allicin play a role in gel formation of myosin from obturator muscle at 300 MPa, whereas allicin and myosin form disulfides as the main factor of myosin gelation. PRACTICAL APPLICATION: To enhance the diversity of scallop preparation methods and improve the quality of the obtained product, UHP and allicin treatment result in scallops with satisfactory chewiness and flavor, which provides application prospects for scallop processing.

Effects of chickpea protein-stabilized Pickering emulsion on the structure and gelling properties of hairtail fish myosin gel.

The effects of different amount (0-12%) of chickpea protein-stabilized Pickering emulsion (CPE) on the gelling properties, intermolecular interactions, microstructure, and physicochemical stability of hairtail fish myosin gels were investigated. The myosin gel with 6%-9% CPE demonstrated significantly higher viscoelasticity, gel strength, hardness, water-holding capacity and whiteness, compared to the control (P < 0.05). In addition, Raman spectroscopy showed that CPE changed the microenvironment of the myosin, which promoted the changes in protein secondary structures, disulfide bond conformation and the local environments of the composite gels. The addition of 6%-9% CPE also enhanced the disulfide bond and hydrophobic interaction of myosin gels which induced more compact gel network structures. Furthermore, CPE improved the lipid oxidative stability and freeze-thaw stability of myosin gel. The results indicated that CPE could improve the gelling properties of myosin, making it a potential new additive and lipid substitute for the development of new emulsion gel products.

Identification, molecular docking, and protective effects on H2O2-induced HEK-293 cell oxidative damage of antioxidant peptides from Pacific saury (Cololabis saira).

We identified novel antioxidant peptides from Pacific saury (Cololabis saira). Enzymatic hydrolysates were isolated, purified, and identified by ultrafiltration, gel chromatography, reverse phase high-performance liquid chromatography (RP-HPLC), and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS). Twenty putative peptides were identified from five components of HPLC, among which sixteen peptides were predicted to have good water solubility and non-toxicity by online tools. Fifteen peptides were successfully docked with myeloperoxidase, and we observed that Arg31, Arg323, and Lys505 played a key role in the antioxidant mechanism, with van der Waals forces and conventional hydrogen bonds as important interaction forces. Six identified peptides with lower CDOCKER energy values were synthesized to verify the antioxidant activity, and the results showed that the synthetic peptide QQAAGDKIMK displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate (31.05 ± 0.27%) and reducing power (0.29 ± 0.01). The synthetic peptide KDEPDQASSK at a concentration of 300 µg mL-1 exhibited the strongest protective effects on H2O2-induced oxidative damage of HEK-293 cells, with cell viability and ROS level of 0.38 ± 0.03 and 0.08 ± 0.01, respectively.

Prediction of the freshness of horse mackerel (Trachurus japonicus) using E-nose, E-tongue, and colorimeter based on biochemical indexes analyzed during frozen storage of whole fish.

Electronic nose (E-nose), electronic tongue (E-tongue) and colorimeter combined with data fusion strategy and different machine learning algorithms (artificial neural network, ANN; extreme gradient boosting, XGBoost; random forest regression, RFR; support vector regression, SVR) were applied to quantitatively assess and predict the freshness of horse mackerel (Trachurus japonicus) during the 90-day frozen storage. The results showed that the fusion data of the E-nose, E-tongue and colorimeter could contain more information (with a total variance contribution rate of 94.734 %) than that of the independent one. ANN, RFR and XGBoost showed good performance in predicting biochemical indexes with the RP2 (the square correlation coefficient of the Test set) ≥ 0.929, 0.936, 0.888, respectively, while SVR models showed a bad performance (RP2 ≤ 0.835). In addition, among the established quantitative models, the RFR model had the best prediction effect on K value (freshness index) with Rp2 of 0.936, ANN model had the highest fitting degree in predicting carbonyl content (protein oxidation degree) with Rp2 of 0.978, XGBoost model had the best performance in predicting the TBA value (lipid oxidation degree) with Rp2 of 0.994, RFR model was the best strategy for predicting Ca2+-ATPase activity (protein denaturation degree) with Rp2 of 0.969. The results demonstrated that the freshness of frozen fish can be effectively evaluated and predicted by the combination of electronic sensor fusion signals.

Plant polyphenols regulating myoglobin oxidation and color stability in red meat and certain fish: A review.

Color is an essential criterion for assessing the freshness, quality, and acceptability of red meat and certain fish with red muscle. Myoglobin (Mb), one of the significant pigment substances, is the uppermost reason to keep the color of red meat. Their oxidation and browning are easy to occur throughout the storage and processing period. Natural antioxidants are substances with antioxidant activity extracted from plants, such as plant polyphenols. Consumers prefer natural antioxidants due to safety concerns and limitations on the use of synthetic antioxidants. In recent years, plant polyphenols have been widely used as antioxidants to slow down the deterioration of product quality due to oxidation. As natural antioxidants, it is necessary to strengthen the researches on the antioxidant mechanism of plant polyphenols to solve the discoloration of red meat and certain fish. A fundamental review of the relationship between Mb oxidation and color stability is discussed. The inhibiting mechanisms of polyphenols on lipid and Mb oxidation are presented and investigated. Meanwhile, this review comprehensively outlines applications of plant polyphenols in improving color stability. This will provide reference and theoretical support for the rational application of plant polyphenols in green meat processing.

Effects of ultrasound pretreatment at different powers on flavor characteristics of enzymatic hydrolysates of cod (Gadus macrocephalus) head.

To make better use of cod head (Gadus macrocephalus), a by-product of fish processing, the effects of ultrasound pretreatment on the enzymatic properties and volatile compounds of cod head enzymatic hydrolysates were investigated. The results demonstrated that ultrasound pretreatment at 150-600 W had a positive effect cod head enzymatic hydrolysates. The soluble peptides content of the enzymatic hydrolysates reached the highest value of 5.31 ± 0.16 mg/mL at the ultrasound power level of 450 W, and the content of peptide molecules < 3-kDa was up to 93.96%. The type and relative content of volatile compounds, especially aldehydes, alcohols, and ketones, also increased with the increase the ultrasound power. The electronic tongue results indicated that ultrasound pretreatment reduced bitterness and astringency. The electronic nose results indicated that the hydrogen- and alkane-containing odor components in the hydrolyzed liquid after ultrasound pretreatment differed significantly from conventional enzymatic hydrolysates. In conclusion, ultrasound pretreatment may be applicable as a suitable technology to assist enzymatic hydrolysis of the cod head, and as such, promote the utilization of fish by-products.

Study on the interactions between the screened polyphenols and Penaeus vannamei myosin after freezing treatment.

The denaturation of proteins (particularly myosin) due to freezing can lead to the deterioration of Penaeus vannamei. The purpose of this study was to verify the antifreeze protective effects of polyphenols screened by a molecular docking technique, and to explore their interactions with myosin after freezing treatment. It was found that the screened polyphenols could significantly increase the freezing rate and unfreezable water content of shrimp paste. The results of fluorescence spectra indicated that the hesperetin to myosin quenching process included both dynamic and static quenching, and it was primarily bound to myosin through hydrophobic interactions; The quenching of myosin by both dihydroquercetin and mangiferin was static quenching, and they were bound to myosin mainly by hydrogen bonds and van der Waals forces; All three of these polyphenols had only one binding site on myosin. Surface hydrophobicity indicated that all four polyphenols were engaged in non-covalent binding (hydrophobic interactions) with myosin. Infrared spectra demonstrated that the addition of these four polyphenols significantly increased the α-helix content of myosin. They also reduced the myosin particle size, zeta potential, and protein degeneration degree. Scanning electron microscopy revealed that the four polyphenols reduced the degree of aggregation, while more uniformly distributing the myosin particles. These observations provide a basis for the screening of polyphenols and further research into the protective mechanism of polyphenols on frozen myosin.

Improvement of the gel properties and flavor adsorption capacity of fish myosin upon yeast ß-glucan incorporation.

The potential effects of yeast ß-glucan (YG) on heat-induced gel properties, microstructure and flavor adsorption capacity of fish myosin at different NaCl concentrations were investigated in this study. The incorporation of YG significantly improved the texture properties, gel strength, water holding capacity (WHC), storage modulus and loss modulus of myosin gels, especially at a high salt level, whereas the whiteness declined. Furthermore, myosin gels containing YG displayed a more compact and ordered three-dimensional network structure, accompanied by the increasing immobilization of water in gels. The binding abilities of gels to selected flavor compounds at high salt content were inferior to those at the low salt content. Regardless of the salt level, YG addition boosted the flavor binding capacity of gels, which might be attributed to the unfolding of the protein conformation by exposing more flavor-binding sites, as well as the porous sponge structure of YG with unique adsorption capacity.

Effect of deacetylated konjac glucomannan on heat-induced structural changes and flavor binding ability of fish myosin.

This work investigated the effects of deacetylated konjac glucomannan (DKGM) on heat-induced structural changes and flavor binding in bighead carp myosin. DKGM could cross-link with fish myosin to form a thermostable complex and improve the gel strength of myosin. The incorporation of DKGM increased the surface hydrophobicity and total sulfhydryl content of heat-induced myosin. Increasing DKGM concentrations resulted in a decrease in the absolute zeta potential and a continuous increase in particle size. DKGM addition significantly reduced the α-helical content of myosin with a concomitant increase in ß-sheet, ß-turn, and random coil content. The binding abilities of myosin to flavors were significantly enhanced by increasing amounts of DKGM, attributing to the accelerative unfolding of myosin secondary structures and the exposure of additional hydrophobic and thiol binding sites. Increased numbers of available hydroxyl groups after DKGM treatment could also cause an increase of flavor adsorption by hydrogen bonding.

Effect of heat treatment duration on the interaction between fish myosin and selected flavor compounds.

BACKGROUND: Interactions between flavor compounds and proteins during food processing are critical to flavor perception of the final product. Here, we investigated the effect of the duration of heat treatment on the interaction between bighead carp myosin and selected flavor compounds including hexanal, heptanal, octanal, nonanal, (E)-2-heptenal, and 1-octen-3-ol. RESULTS: The binding of flavor compounds to native myosin was strong and decreased in the order nonanal > octanal > (E)-2-heptenal > heptanal > hexanal >1-octen-3-ol. The aldehydes, especially trans-2-undecenal, were more conducive to hydrophobic binding to myosin than alcohols. Within the initial 5 min of heating, the surface hydrophobicity and total sulfhydryl exposure increased, while α-helix turned into ß-sheets, ß-turns, and random coils. However, upon further heating, the hydrophobicity and sulfhydryl contents declined, ß-sheets, ß-turns and random coils shifted to α-helix. Throughout the heating process, the particle size increased, and the absolute zeta potential decreased continuously, indicating that thermal aggregation of myosin occurred simultaneously. Changes in binding capacities of flavor compounds to myosin were consistent with changes in hydrophobicity and sulfhydryl contents. CONCLUSION: The initial enhancement of the flavor-binding capacity of myosin was attributed to the unfolding of secondary structures by exposing more hydrophobic bonding sites and hydrogen bonding sites. The rebuilding and aggregating of myosin was enhanced upon prolonged heating, thus favoring hydrophobic protein-protein interactions and weakening the resultant flavor binding capacity of myosin.

Identification, taste characteristics and molecular docking study of novel umami peptides derived from the aqueous extract of the clam meretrix meretrix Linnaeus.

To understand the delicious taste of the clam M. meretrix Linnaeus, the putative umami peptides from the aqueous extract of the cooked clam were obtained by ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography. The isolated peptide fraction with the most intense umami taste was screened by sensory and electronic tongue analysis. Seven novel peptides, GLLPDGTPR, RPNPFENR, STMLLESER, ANPGPVRDLR, QVAIAHRDAK, VLPTDQNFILR, and VTADESQQDVLK, were identified and synthesized to verify their taste characteristics. The taste activity prediction and the sensory evaluation of the synthetic peptides revealed that those peptides were umami and umami-enhancing peptides. Docking of the synthesized peptides with the umami taste receptor T1R1/T1R3 indicated that the peptides could enter the binding pocket in the Venus flytrap domain of the T1R3 cavity, wherein Asp196 and Glu128 may play key roles in the synergism of umami taste and hydrogen bonding and electrostatic interactions are important interaction forces.

Effect of 6-gingerol on physicochemical properties of grass carp (Ctenopharyngodon idellus) surimi fortified with perilla oil during refrigerated storage.

BACKGROUND: Surimi is produced from deboned fish muscle through washing to remove blood, lipids, sarcoplasmic proteins and other impurities. There is an increasing interest in the fortification of surimi with ω-3 polyunsaturated fatty acids because of their health benefits. However, lipid oxidation should be considered as an important factor during storage. Hence, in this study, the quality properties and oxidative stability of surimi fortified with 30 g kg-1 perilla oil (PO), or 5 g kg-1 6-gingerol (GI) or their combination (PO+GI) was investigated. RESULTS: Perilla oil significantly improved whiteness of surimi gel, but negatively influenced its gel strength, water holding capacity (WHC) and texture. However, there was no significant difference in texture properties among GI, PO+GI and control groups. During the whole storage period, GI and PO+GI groups had higher gel strength and WHC than control and PO groups. Moreover, lower thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), carbonyl content and total plate count (TPC) were observed in GI group compared with other groups. CONCLUSION: Perilla oil and 6-gingerol could be applied together to effectively fortify surimi qualities. Additionally, 6-gingerol could prevent lipid and protein oxidation and microbial growth of surimi during refrigerated storage. © 2017 Society of Chemical Industry.

Antimicrobial effect and membrane-active mechanism of tea polyphenols against Serratia marcescens.

In this study, we investigated the antimicrobial effect of tea polyphenols (TP) against Serratia marcescens and examined the related mechanism. Morphology changes of S. marcescens were first observed by transmission electron microscopy after treatment with TP, which indicated that the primary inhibition action of TP was to damage the bacterial cell membranes. The permeability of the outer and inner membrane of S. marcescens dramatically increased after TP treatment, which caused severe disruption of cell membrane, followed by the release of small cellular molecules. Furthermore, a proteomics approach based on two-dimensional gel electrophoresis and MALDI-TOF/TOF MS analysis was used to study the difference of membrane protein expression in the control and TP treatment S. marcescens. The results showed that the expression of some metabolism enzymes and chaperones in TP-treated S. marcescens significantly increased compared to the untreated group, which might result in the metabolic disorder of this bacteria. Taken together, our results first demonstrated that TP had a significant growth inhibition effect on S. marcescens through cell membrane damage.

Effect of tea polyphenols on microbiological and biochemical quality of Collichthys fish ball.

BACKGROUND: Tea polyphenols (TP), as the most active constituents of tea, are considered natural food additives. This study examined the preservative properties of TP for Collichthys fish ball in well storage. Vacuum-packed Collichthys fish balls were treated with 0, 0.1, 0.15, 0.20, 0.25, and 0.30 g kg(-1) TP and stored at 0 °C for 17 days. RESULTS: Microbiological results were obtained using a biochemical test, API system kit, and 16S rDNA sequence analysis. Results confirmed that the dominant bacteria in Collichthys fish balls are the genera Serratia and Pseudomonas. Total viable counts dropped two orders of magnitude in Collichthys fish balls with 0.25 g kg(-1) TP compared with the control. The advantages of total volatile basic nitrogen value, 2-thiobarbituric acid value and texture value were clearly observed, whereas pH and whiteness value exhibited no significant decrease for the group treated with 0.25 g kg(-1) TP. More than 0.25 g kg(-1) TP added could retain excellent fish ball characteristics in terms of sensory assessment after 17 days. CONCLUSION: The shelf life of Collichthys fish balls supplemented with tea polyphenols can be prolonged for an additional 6 days in good condition at 0 °C storage.

Tea polyphenols inhibit Pseudomonas aeruginosa through damage to the cell membrane.

This paper aims to delineate the inhibition mechanism of tea polyphenols (TP) toward Pseudomonas aeruginosa by cell membrane damage. Morphological changes in bacteria treated with TP were investigated by transmission electron microscopy, with results indicating that the primary inhibitory action of TP is to damage bacterial cell membranes. TP also increased the permeability of the outer and inner membranes of P. aeruginosa and disrupted the cell membrane with the release of small cellular molecules. A proteomics approach based on two-dimensional gel electrophoresis and MALDI-TOF/TOF MS analysis was used to study the differences in the membrane proteins of TP-treated P. aeruginosa and those of control samples. Twenty-seven differentially expressed proteins were observed in the treated and the control groups. Most of the proteins identified by MALDI-TOF/TOF MS were enzymes (dihdrollpoamide dehydrogenase 50s ribosomal protein, and so on), which may have induced the metabolic disorder of the bacteria and resulted in their death.