Enhancing bighead carp cutting: Chilled storage insights and machine vision-based segmentation algorithm development.

To enhance market demand and fish utilization, cutting processing is essential for fish. Bighead carp were cut into four primary cuts: head, dorsal, belly, and tail, collectively accounting for 77.03% of the fish's total weight. These cuts were refrigerated at 4 °C for 10 days, during which the muscle from each cut was analyzed. Pseudomonas.fragi proliferated most rapidly and was most abundant in eye muscle (EM), while Aeromonas.sobria showed similar growth patterns in tail muscle (TM). Notably, EM exhibited the highest rate of fat oxidation. TM experienced the most rapid protein degradation. Furthermore, to facilitate the cutting applied in mechanical processing, a machine vision-based algorithm was developed. This algorithm utilized color threshold and morphological parameters to segment image background and divide bighead carp region. Consequently, each cut of bighead carp had a different storage quality and the machine vision-based algorithm proved effective for processing bighead carp.

Plastein reaction augments the metal chelating capabilities of silver carp (Hypophthalmichthys molitrix) hydrolysates: Unlocking the chemical modification mechanism.

Plastein reaction mechanisms and the alteration of its product properties have been studied for decades. This study investigated the plastein-mediated modifications in silver carp protein hydrolysate (SCPH) from both mechanistic and functional perspectives. Unlike prior research, this investigation uncovered that hydrogen bonding supplemented the dominant hydrophobic interactions in plastein's mechanism for the first time, as supported by peptide concentrations, molecular weight, amino acids, chemical forces, and peptide sequence by LC-MS/MS. This innovative reaction mechanism cascaded into the enhancement of SCPH functional attributes. Plastein induced increased COOH in SCPH's side-chain groups significantly enhanced Fe2+ (from 4.49 to 14.12 %) and Zn2+ (from 53.53 to 64.47 %) chelation. Moreover, the elevated DPPH (17.56 %-23.97 %) and hydroxyl radical (68.49 %-79.32 %) scavenging power indicated a broader improvement in SCPH with plastein. In SCPH, plastein elucidated reaction intricacies and enhanced its utility, propelling SCPH into a realm of extended potential.

Protein oxidation-mediated changes in digestion profile and nutritional properties of myofibrillar proteins from bighead carp (Hypophthalmichthys nobilis).

Digestibility is an important factor in accessing the nutritional quality and potential health benefits of protein. In this study, exudates were utilized to incubate myofibrillar proteins (MPs) for simulating the oxidation of MPs in frozen-thawed fish fillets. An in vitro gastrointestinal system was used to investigate the effect of protein oxidation on the digestion profile and nutritional properties of MPs. Results showed that exudates treatment caused the moderate oxidation of MPs and its digestibility thus increased, hydroxyl radical generation system treatment reduced the digestibility significantly. The analysis of SDS-PAGE, tricine-SDS-PAGE, amino acid composition, and peptidomics of digestion products indicates that protein oxidation decreases digestibility by causing protein cross-linking, degradation, and amino acid residues conversion. Additionally, protein oxidation reduces nutritional value of MPs via several ways including loss of essential amino acids, the proportion increase of macromolecular peptides (>2 kDa) in digests, and the percentage decrease of potential bioactive peptides in digests. The present study provides an intuitive insight into the impact of protein oxidation in frozen/thawed fillets on the digestibility of MPs, emphasizing the importance of mitigating protein oxidation to preserve their nutritional quality.

Mastering the art of taming: Reducing bitterness in fish by-products derived peptides.

Processed fish by-products are valuable sources of peptides due to their high protein content. However, the bitterness of these peptides can limit their use. This review outlines the most recent advancements and information regarding the reduction of bitterness in fish by-products derived peptides. The sources and factors influencing bitterness, the transduction mechanisms involved, and strategies for reducing bitterness are highlighted. Bitterness in peptides is mainly influenced by the source, preparation method, presence of hydrophobic amino acid groups, binding to bitter receptors, and amino acid sequence. The most widely utilized techniques for eliminating bitterness or enhancing taste include the Maillard reaction, encapsulation, seperating undesirable components, and bitter-blockers. Finally, a summary of the current challenges and future prospects in the domain of fish by-products derived peptides is given. Despite some limitations, such as residual bitterness and limited industrial application, there is a need for further research to reduce the bitterness of fish by-products derived peptides. To achieve this goal, future studies should focus on the technology of fish by-products derived peptide bitterness diminishment, with the aim of producing high-quality products that meet consumer expectations.

Dual cryoprotective and antioxidant effects of young apple polyphenols on myofibrillar protein degradation and gelation properties of bighead carp mince during frozen storage.

Commercial cryoprotectants can delay quality loss in frozen fish mince, but they are associated with a sweet taste and high calorie content. Young apple polyphenols (YAP), extracted from unripe apples, show potential as an alternative cryoprotectant. This study evaluated the cryoprotective effect of YAP at varying levels (0.3%, 0.7%, and 1%) in unwashed bighead carp mince. The changes in sulfhydryl content, carbonyl content, thiobarbituric acid reactive substances, intrinsic fluorescence intensity, and Fourier transform infrared spectrum indicated that YAP retarded oxidation and structural changes in myofibrillar proteins during the first 8 weeks of frozen storage, as well as lipid oxidation, which protected the structure of myofibrillar protein. At higher concentrations (0.7% and 1%), YAP maintained gel properties, gel springiness, and water-holding capacity of the gel prepared from frozen fish mince, potentially through the promotion of cross-linking of myofibrillar proteins. Overall, YAP can be used as a cryoprotectant and antioxidant in fish mince. PRACTICAL APPLICATION: Our research found that young apple polyphenols have the potential to be an alternative to commercial cryoprotectants. Young apple polyphenols may be used as a sugar-free and healthy cryoprotectant for frozen fish mince production in the future.

Whey Protein Hydrolysate Exerts Anti-Inflammatory Effects to Alleviate Dextran Sodium Sulfate (DSS)-Induced Colitis via Microbiome Restoration.

Whey protein hydrolysate (WPH) has been shown to have a variety of bioactivities. This study aimed to investigate the preventive effect of WPH on dextran sodium sulfate (DSS)-induced colitis in C57BL/6J mice. The results indicated that WPH intervention for 37 days was effective in delaying the development of colonic inflammation, and high doses of WPH significantly inhibited weight loss (9.16%, n = 8, p < 0.05), protected the colonic mucosal layer, and significantly reduced the levels of inflammatory factors TNF-α, IL-6, and IL-1ß in mice with colitis (n = 8, p < 0.05). In addition, WPH intervention was able to up-regulate the short-chain fatty acids secretion and restore the gut microbiome imbalance in mice with colitis. Notably, high-dose WPH intervention increased the relative abundance of norank_f_Muribaculaceae by 1.52-fold and decreased the relative abundance of Romboutsia and Enterobacter by 3.77-fold and 2.45-fold, respectively, compared with the Model group. WPH intervention protected colitis mice mainly by reversing the microbiome imbalance and regulating the major histocompatibility complex (MHC) class I pathway. This study showed that WPH has anti-inflammatory activity and a promising colitis management future.

Oxidation and side-chain modifications decrease gastrointestinal digestibility and transport of proteins from salted bighead carp fillets after frozen storage.

This study examined the effects of protein oxidation on digestion behavior. The oxidation levels and in vitro digestibility of myofibrillar proteins from fresh-brined and frozen bighead carp fillets were investigated, and the intestinal transport property was characterized by comparing the peptides on both sides of the intestinal membrane. Frozen fillets showed high oxidation levels, low amino acid content and in vitro protein digestibility, which were further increased by brining. After storage, the number of modified peptides from myosin heavy chain (MHC) increased over 10-fold in NaCl-treated samples (2.0 M). Various types of side-chain modifications in amino acids were identified, such as di-oxidation, α-aminoadipic semialdehyde (AAS), γ-glutamic semialdehyde (GGS), and protein-malondialdehyde (MDA) adducts, mainly originating from MHC. The Lysine/Arginine-MDA adducts, AAS, and GGS decreased protein digestibility and their intestinal transportation. These findings suggest that oxidation impacts protein digestion and should be considered in food processing and preservation strategies.

Changes in Lipids and Proteins of Common Carp (Cyprinus carpio) Fillets under Frozen Storage and Establishment of a Radial Basis Function Neural Network (RBFNN).

Storage via freezing remains the most effective approach for fish preservation. However, lipid oxidation and protein denaturation still occur during storage, along with nutritional loss. The extent of lipid alteration and protein denaturation are associated with human health defects. To precisely predict common carp (Cyprinus carpio) nutritional quality change during frozen storage, here, we first determined lipid oxidation and hydrolysis and protein denaturation of common carp fillets during 17 weeks of frozen preservation at 261 K, 253 K, and 245 K. Results showed that the content of thiobarbituric acid reactive substances (TBARS) and free fatty acids (FFA) were significantly increased. However, salt-soluble protein (SSP) content, Ca2+-ATPase activity, and total sulfhydryl (SH) content kept decreasing during frozen storage, with SSP content decreasing by 64.82%, 38.14%, and 11.24%, respectively, Ca2+-ATP enzyme activity decreasing to 12.50%, 18.52%, and 28.57% Piµmol/mg/min, and SH values decreasing by 70.71%, 64.92%, and 56.51% at 261 K, 253 K, and 245 K, respectively. The values at 261 K decreased more than that at 253 K and 245 K (p < 0.05). Ca2+-ATPase activity was positively correlated (r = 0.96) with SH content. Afterwards, based on the results of the above chemical experiments, we developed a radial basis function neural network (RBFNN) to predict the modification of lipid and protein of common carp fillets during frozen storage. Results showed that all the relative errors of experimental and predicted values were within ±10%. In summary, the quality of common carp can be well protected at 245 K, and the established RBFNN could effectively predict the quality of the common carp under frozen conditions at 261-245 K.

Experimental evidence of ß-relaxation and its structural origin in ZIF-62 glass.

Intrinsic relaxation processes determine the crucial properties of glass, yet their underlying mechanisms are far from well understood. The brand-new glass-forming metal-organic frameworks (MOFs) provide desirable opportunities for looking inside glass relaxation, especially the secondary ß-relaxation phenomenon and mechanism. For a representative zeolitic imidazolate framework-62 (ZIF-62) glass, reliable and fine powder mechanical spectroscopy was performed based on home-made mountings combined with a commercial dynamical mechanical analyzer. For the first time, ß-relaxation was observed in a MOF glass besides the primary α-relaxation. The pronounced ß-relaxation was well demonstrated by a number of characteristics including an excess wing and the full width at half maximum (W) of the α-relaxation peaks, which deviated from the time-temperature superposition. The stretched exponent ß of ZIF-62 glass is 0.71 in the supercooled region. The W of ZIF-62 glass is the maximum among all known glassy materials. The structural origin of α- and ß-relaxation can be attributed to an increase of density, as observed using nuclear magnetic resonance (NMR). A general linear and broad correlation of fragility and stretched exponent ß with W of the α-relaxation peaks was established. When compared with traditional glass-formers, the resulting principles indicate a shared origin for the stretched exponent ß, W, and ß-relaxation in the case of ZIF-62 glass. The presented findings offer an effective new method to explore the glass/liquid transition of MOF glasses, which helps to obtain a deeper insight into the hierarchical relaxation dynamics of the glass transition.

Effects of protein and lipid oxidation on the water holding capacity of different parts of bighead carp: Eye, dorsal, belly and tail muscles.

The quality of fish can change due to differences in the lipid and protein oxidation rates in different muscles. This study examined vacuum-packed eye muscle (EM), dorsal muscle (DM), belly muscle (BM), and tail muscle (TM) of bighead carp frozen for 180 days. The results reveal that EM had the highest lipid content and the lowest protein content, while DM had the lowest lipid content and the highest protein content. EM also showed the highest values of centrifugal loss and cooking loss, and the correlation analysis showed that these losses were positively correlated with dityrosine content and negatively correlated with conjugated triene content. The content of carbonyl, disulfide bond, and surface hydrophobicity of myofibrillar protein (MP) also increased with time, with DM having the highest values. The microstructure of EM was looser than other muscles. Therefore, DM had the fastest oxidation rate and EM had the lowest water holding capacity.

Milk Fat Globule Membrane Relieves Fatigue via Regulation of Oxidative Stress and Gut Microbiota in BALB/c Mice.

Milk fat globule membranes (MFGMs) are complex structures that incorporate bioactive proteins and lipids to assist in infant development. However, the antifatigue and antioxidant potentials of MFGM have not been investigated. In this study, repeated force swimming measured fatigue in male BALB/c mice fed MFGM and saline for 18 weeks. The MFGM supplementation increased the time to exhaustion by 42.7% at 6 weeks and 30.6% at 14 weeks (p < 0.05). Fatigue and injury-related biomarkers, including blood glucose, lactic acid, and lactate dehydrogenase, were ameliorated after free swimming (p < 0.05). The activity of antioxidant enzymes in blood serum increased at 18 weeks, while malondialdehyde (MDA) content decreased by 45.0% after the MFGM supplementation (p < 0.05). The Pearson correlation analysis showed a high correlation between fatigue-related indices and antioxidant levels. The increased protein expression of hepatic Nrf2 reduced the protein expression of Caspase-3 in the gastrocnemius muscle (p < 0.05). Moreover, the MFGM supplementation increased the relative abundance of Bacteroides, Butyricimonas, and Anaerostipes. Our results demonstrate that MFGM may maintain redox homeostasis to relieve fatigue, suggesting the potential application of MFGM as an antifatigue and antioxidant dietary supplement.

Whey Protein Hydrolysate Renovates Age-Related and Scopolamine-Induced Cognitive Impairment.

Whey protein and its hydrolysates are ubiquitously applied in the food system. However, their effect on cognitive impairment remains unclear. This study aimed to investigate the potential ability of whey protein hydrolysate (WPH) to ameliorate cognitive degeneration. WPH intervention in Crl:CD1 (ICR, Institute for cancer research) mice and aged C57BL/6J mice in a scopolamine-induced cognitive impairment model for 10 days were evaluated. Behavioral tests indicated that WPH intervention improved the cognitive abilities in ICR and aged C57BL/6J mice (p < 0.05). Scopolamine enhanced the Aß1-42 level in the brain tissue, and the WPH intervention exhibited a similar therapeutic effect to donepezil in ICR mice. A noticeable reduction occurred in serum Aß1-42 level of aged mice treated with WPH. The histopathological study of the hippocampus showed that WPH intervention alleviates neuronal damage. Hippocampus proteomic analysis suggested possible mechanisms of WPH action. The relative abundance of Christensenellaceae, a gut microbe related to Alzheimer's disease, was altered by WPH intervention. This study demonstrated that short-term WPH intake protected against memory impairment induced by scopolamine and aging.

Novel Hypocholesterolemic Peptides Derived from Silver Carp Muscle: The Modulatory Effects on Enterohepatic Cholesterol Metabolism In Vitro and In Vivo.

This research aimed to investigate the effect of silver carp hydrolysates (SCHs) on hypercholesterolemia and enterohepatic cholesterol metabolism. Results showed that in vitro gastrointestinal digestion products of Alcalase-SCH (GID-Alcalase) exhibited the highest inhibitory activity of cholesterol absorption mainly through downregulating the expression of essential genes related to cholesterol transport in a Caco-2 monolayer. After being absorbed by the Caco-2 monolayer, GID-Alcalase increased the low-density lipoprotein (LDL) uptake in HepG2 cells by enhancing the protein level of the LDL receptor (LDLR). The in vivo experiment showed that long-term intervention of Alcalase-SCH ameliorated hypercholesterolemia in ApoE-/- mice fed with a Western diet (WD). After transepithelial transport, four novel peptides (TKY, LIL, FPK, and IAIM) were identified, and these peptides possessed dual hypocholesterolemic functions including inhibition of cholesterol absorption and promotion of peripheric LDL uptake. Our results indicated for the first time the potential of SCHs as functional food ingredients for the management of hypercholesterolemia.

Improvement of Spatial Memory and Cognitive Function in Mice via the Intervention of Milk Fat Globule Membrane.

With the improvement of living standards, dietary interventions have become an appropriate approach to enhance memory and cognitive performance. The present study investigated the potential mechanisms of spatial memory and cognitive function improvement with the milk fat globule membrane (MFGM) intervention in mice. The Morris water maze experiment revealed that the trajectories of mice in group M were more disordered. Also, the immunohistochemical results demonstrated a significantly higher number of neurons in group M compared with group C, especially in the hippocampal dentate gyrus (DG) area. It is suggested that MFGM enhanced mice's spatial memory and cognition from macroscopic behavior and microscopic cytology, respectively. Meanwhile, 47 differentially expressed proteins (DEPs) were identified, including 20 upregulated and 27 downregulated proteins. Upregulated (Sorbs 2, Rab 39, and Cacna 1e) and downregulated (Hp and Lrg 1) DEPs may improve spatial memory and cognition in mice by promoting synapse formation and increasing neurotransmitter receptors. KEGG enrichment analysis of the DEPs identified seven signaling pathways that were significantly enriched (p < 0.05). One of these pathways was neuroactive ligand-receptor interactions, which are strongly associated with improved spatial memory and cognitive performance. These findings give some new insights and references to the potential mechanisms of spatial memory and cognitive enhancement by MFGM.

Uncovering quality changes of salted bighead carp fillets during frozen storage: The potential role of time-dependent protein denaturation and oxidation.

This study aimed to find the specific relationship between quality traits and myofibrillar proteins (MPs) alteration of salted fish during frozen storage. Protein denaturation and oxidation occurred in frozen fillets, with the denaturation occurring before oxidation. In the pre-phase of storage (0-12 weeks), protein structural changes (secondary structure and surface hydrophobicity) were closely related to the water-holding capacity (WHC) and textural properties of fillets. The MPs oxidation (sulfhydryl loss, carbonyl and Schiff base formation) were dominated and associated with changes in pH, color, WHC, and textural properties during the later stage of frozen storage (12-24 weeks). Besides, the brining at 0.5 M improved the WHC of fillets with less undesirable changes in MPs and quality traits compared to other concentrations. The 12 weeks was an advisable storage time for salted frozen fish and our results might provide an available suggestion for fish preservation in aquatic industry.

Protein oxidation affected the digestibility and modification sites of myofibrillar proteins from bighead carp fillets treated with hydroxyl radicals and endogenous oxidizing system.

This study aimed to investigate the effect of hydroxyl radical oxidizing system (HROS) and endogenous oxidizing system (EOS, i.e., frozen storage at -20 °C) on protein oxidation, digestive properties, and peptide modification of myofibrillar proteins (MPs) in bighead carp (Hypophthalmichthys nobilis) fillets. The oxidation degree increased with the frozen time and H2O2 concentration as evidenced by carbonyl group generation and sulfhydryl group loss in MPs. The digestibility of protein declined gradually during frozen storage, while it increased after treatment with 5 mM H2O2 compared with no H2O2 intervention. More modification numbers and types were observed in the EOS group than HROS in digested MPs peptides, which might be due to the complexity of the frozen fillet system such as the presence of lipid. The potential conversion of α-aminoadipic semialdehyde (AAS) to α-aminoadipic acids (AAA) was observed in HROS. Additionally, the myosin heavy chain was more susceptible to oxidation among all MPs by EOS oxidation.

Insight into the protein oxidation impact on the surface properties of myofibrillar proteins from bighead carp.

The objective of this study was to elucidate the influence of oxidative modifications of myofibrillar proteins (MPs) on their surface properties. Oxidative modifications (deamination, formation of disulfide bonds and Schiff bases), particle size, net surface charge, and binding ability of volatiles (2-enthylfuran, 1-octen-3-ol, hexanal, and octanal) of oxidized MPs was measured. Molecular docking of volatiles with actomyosin was performed using Qvina-W program and the specific oxidative modifications (monoxidation and deamination) of MPs were determined using LC-MS/MS. Results showed that oxidation of Cys (forming sulfinic, sulfonic, sulfenic acid, and disulfide bonds), monoxidation of Ala, Lys, Glu, and Asn, and deamination of Lys changed the surface properties of oxidized MPs including enhanced surface hydrophobicity and decreased affinity to volatile compounds and water. Overall, this study gives evidence of how protein oxidation affects the properties of MPs and therefore deteriorates fish meat quality.

Interaction and phase behavior of whey protein and propylene glycol alginate complex condensates.

Whey protein (WP) is ubiquitously applied in food products, but its sensitivity to food processing conditions has limited its application. Herein, we chose propylene glycol alginate (PGA) to combine with WP to enhance its stability. The ideal ratio of WP/PGA for coacervation was 3:1, and the soluble complex and insoluble complex were formed at pH 5.2 (pHc) and pH 4.4 (pHφ1) at this ratio, respectively. The UV absorption spectra, fluorescence spectra, and XRD results revealed that the interaction between PGA and WP changed the tertiary conformation of WP. The FTIR and molecular docking results suggested electrostatic interactions, hydrogen bonding and hydrophobic interactions were all involved in the formation of WP-PGA complexes, and the thermal stability of WP was improved based on the DSC results. These findings supported PGA to keep dairy products stable and transparent at the isoelectric point and WP-PGA complexes could be applied in encapsulating bioactive substances.

Silver carp (Hypophthalmichthys molitrix) by-product hydrolysates: A new nitrogen source for Bifidobacterium animalis ssp. lactis BB-12.

Appropriate utilization of silver carp by-products is critical for enhancing industry profit and sustainability of aquaculture. This study explored the effect of the silver carp by-product hydrolysates on the growth of Bifidobacterium animalis ssp. lactis BB-12. Results indicated that papain recovered more nitrogen and < 1 kDa components from silver carp by-products than neutrase and alcalase. Papain-2 h (by-products hydrolyzed by papain for 2 hrs) was more effective in promoting the growth of BB-12. The content of < 1 kDa components, sulfhydryl-containing amino acids, and peptides composed of all the hydrophobic amino acids in hydrolysates was positively correlated to the growth of BB-12. BB-12 cultured by papain-2 h substituted medium exhibited a thinner and shorter morphology at 4 hrs of cultivation. This study provided a new nitrogen source for Bifidobacterium animalis ssp. lactis BB-12 and possible strategy for converting by-products to reduce aquacultural waste.

Gut microbiota and metabolic profile as affected by Maillard reaction products derived from bighead carp meat hydrolysates with galactose and galacto-oligosaccharides during in vitro pig fecal fermentation.

Maillard reaction products (MRPs) play pivotal roles in gut health by affecting the microbiome-host interactions. This study aimed at investigating the effects of MRPs derived from bighead carp meat hydrolysates with galactose and galacto-oligosaccharides on intestinal microbial composition and metabolic profile by in vitro pig fecal fermentation. The pH decreased sharply in the first 12 h and the highest production of butyric acid was observed in GM (glycated BCH with galacto-oligosaccharide) treatment with 64.7 µmoL/10 mL (p < 0.05) at 48 h. Clostridium_sensu_stricto_1, Streptococcus, and Enterococcus were dominant in the GM treatment, while Escherichia-Shigella was predominant in LgM (glycated BCH with galactose) treatment at 12 h. The up-regulated metabolites indicated that GM and LgM might participate in the fatty acids synthesis and modulate lipid metabolism, respectively. Overall, GM will be more beneficial for gut health by promoting the production of butyric acid and fatty acids synthesis.