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The impacts of natural antioxidants, including ferulic acid, diallyl sulfide, α-tocopherol, and rutin, at a level of 0.2 g/kg on lipid and protein oxidation of minced yak meat in a hydroxyl-radical-generating system were investigated, and the effectiveness was compared with synthetic antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). The exposure of yak meat to oxidative stress from 12 h to 24 h elevated lipid and protein oxidation. Treatments with antioxidants resulted in significantly lower peroxides, conjugated dienes, and thiobarbituric acid-reactive substances, and were also effective in retarding the formation of carbonyl groups, reducing the loss of sulfhydryl groups and protecting α-helix contents, of which ferulic acid and rutin were the most effective. Myosin heavy chain underwent lower degradation in the samples treated with ferulic acid or rutin compared with the oxidized control and other antioxidant treatments, while that of the BHT treatment showed a similar intensity with oxidized control at 24 h of oxidation. The physical stability of myofibrillar proteins in samples with antioxidants from high to low was rutin, ferulic acid, α-tocopherol, and BHT~diallyl sulfide. These results indicate that rutin and ferulic acid may be promising antioxidants in inhibiting the oxidative reactions during the processing of yak meat. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the protein oxidation of soybean meal (SBM) stored in a warehouse and the effects of SBM on growth performance, antioxidant status, digestive performance, intestinal morphology, and breast muscle quality of broilers., Methods: In total, 160 one-day-old Arbor Acres Plus broilers (half male and half female) were randomly divided into two groups with ten replicates of eight birds each: The control group was served with a basal diet including SBM stored at -20°C (FSBM), and the experimental group was served with a basal diet including SBM stored in a warehouse at room temperature for 45 days (RSBM)., Results: Compared with FSBM, the protein carbonyl level in RSBM was increased, the free and total thiol levels and in vitro digestibility of protein were decreased. The RSBM decreased the serum glutathione (GSH) level and the hepatic total superoxide dismutase (T-SOD) activity at days 21 and 42 when compared with FSBM. Further, RSBM reduced the duodenal T-SOD activity, jejunal catalase (CAT), and T-SOD activities at day 21, and decreased the duodenal CAT and T-SOD activities, jejunal T-SOD activity, and ileal GSH level and T-SOD activity at days 21 and 42 when compared with FSBM. Besides, the trypsin activity and the ratio of villus height to crypt depth in small intestines of broilers at days 21 and 42 were reduced when fed with a RSBM-contained diet. Compared with FSBM, the 24-h drip loss, shear force, and 24- and 48-h cooking loss of breast muscle were increased of RSBM group, the opposite result was observed for muscle lightness at 48 h., Conclusion: Room temperature storage for 45 days led a protein oxidation and decreased in vitro digestibility in SBM, and fed RSBM impaired growth performance, antioxidant status, and meat quality, reduced trypsin activity, and affected the small intestine morphology in broilers.

The active site Cys residue in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is sensitive to oxidation by hydrogen peroxide (H2O2), with this resulting in enzyme inactivation. This re-routes the carbon flux from glycolysis to the pentose phosphate pathway favoring the formation of NADPH and synthetic intermediates required for antioxidant defense and repair systems. Consequently, GAPDH inactivation serves as a redox switch for metabolic adaptation under conditions of oxidative stress. However, there is a major knowledge gap as to how GAPDH is efficiently oxidized and inactivated, when the increase in intracellular H2O2 is modest, and there is a high concentration of alternative (non-signaling) thiols and efficient peroxide removing systems. We have therefore explored whether GAPDH inactivation is enhanced by two factors of in vivo relevance: macromolecular crowding, an inherent property of biological environments, and the presence of bicarbonate, an abundant biological buffer. Bicarbonate is already known to modulate H2O2 metabolism via formation of peroxymonocarbonate. GAPDH activity was assessed in experiments with low doses of H2O2 under both dilute and crowded conditions (induced by inert high molecular mass polymers and small molecules), in both the absence and presence of 25 mM sodium bicarbonate. H2O2-induced inactivation of GAPDH was observed to be significantly enhanced under macromolecular crowding conditions, with bicarbonate having an additional effect. These data strongly suggest that these two factors are of major importance in redox switch mechanisms involving GAPDH (and possibly other thiol-dependent systems) within the cellular environment., (Copyright 2024 The Author(s).)

In this study, the relationship between advanced glycosylation end products (AGEs) in preserved egg white (PEW) with protein oxidation and precursors induced by OH - and Cu 2+ were performed to clarify the differential contribution of OH - and Cu 2+ on the formation of AGEs during pickling. It was found that AGEs were more easily formed in PEW rather than yolk, and the accumulation of N ε -carboxymethyllysine (CML) could be promoted through protein oxidation related to carbonyl compounds, tryptophan induced by Cu 2+ at early stage, while carbonyl compounds were more conducive to form N ε -carboxyethyllysine (CEL) under synergistic action of Cu 2+ and OH - . At later period, Schiff base promoted the formation of CEL and CML in the presence of Cu 2+ . Meanwhile, the enrichment of CEL and CML could both be promoted by α-dicarbonyl compounds in presence of Cu 2+ and/or OH - . This manuscript will provide theoretical guidance for reducing and limiting hazardous compounds in preserved eggs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This work systematically investigated the effects of pre-slaughter transport stress on pork water holding capacity (WHC) during aging from the perspectives of oxidation, structure, function, and degradation properties of protein. Pigs were randomly divided into three-hour transport (Transport-induced stress, T group) and three-hour transport followed by three-hour resting (Control, TR group). Results demonstrated that T treatment markedly declined pork WHC. Compared with TR group, T group presented increased oxidation levels. Meanwhile, T treatment exacerbated the shift of protein secondary structure from α-helix to random coil and protein unfolding levels. The decreased solubility, thermal stability, and degraded levels of proteins were also observed in T group. Additionally, muscle contractions of T group were more severe than TR group. This study supported that pre-slaughter transport stress altered physicochemical properties and structures of postmortem muscle proteins, which reduced pork WHC via impairing the interactions between protein and water molecules and changing the muscle fiber structure., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

In this study, the effect of L-arginine (L-Arg) on the oxidative aggregation of myofibrillar proteins (MPs) in Antarctic krill was evaluated. The results showed that the oxidized aggregation of MPs was significantly inhibited after the addition of 20 mM L-Arg compared to the oxidized group, the solubility of MPs significantly increased by 25.74 %, the turbidity reduced from 0.56 to 0.18. These effects were primarily attributed to the addition of L-Arg, which prevented the unfolding of the spatial structure of MPs after oxidation, inhibited the formation of disulfide bonds and dityrosine, and improved the stability of MPs structure. Analysis of carbonyl content and hydroxyl radical (•OH) inhibitory capacity showed that carbonyl formation and hydroxyl radicals were effectively reduced by the pH and guanidinium group of L-Arg. The pH of L-Arg exhibited a significantly higher effect than the guanidinium group in inhibiting the oxidative aggregation of MPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The Chilean papaya ( Vasconcellea pubescens A.DC.) is a climacteric fruit that grows in the north and center of Chile. During its processing, residues formed mainly by mucilage and seeds are produced and mostly discarded, despite being a potential source of bioactive metabolites. This work aimed to apply untargeted metabolic analysis by HPLC-DAD-QToF to study the chemical composition of ethyl acetate and methanol extracts from Chilean papaya residues and evaluate their antioxidant and antiglycation capacities. Twenty-three metabolites were tentatively identified in papaya residues, including one carboxylic acid, one glycosylated hydroquinone, four flavan-3-ols, three proanthocyanidins, twelve glycosylated flavonols, one carbohydrate, and one alkaloid reported for the first time. The antioxidant capacity measured as the scavenging of DPPH • and ABTS •+ radicals was comparable with that of ascorbic acid. Chilean papaya extracts decreased fluorescent Advanced Glycation End (AGE) products and oxidative modifications in proteins induced by glucose., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

This paper focuses on the changes of physicochemical properties and gel-forming ability of duck myofibrillar proteins (DMPs) induced using hydroxyl radical oxidizing systems. DMPs were firstly extracted and then oxidized at various H2O2 concentrations (0, 4, 8, and 12 mmol/L) using Fenton reagent (Fe3+-Vc-H2O2) to generate hydroxyl radicals, and the effects of hydroxyl radical oxidation on the physicochemical changes and heat-induced gel-forming capacity of DMPs were analyzed. We observed obvious increases in the carbonyl content (p < 0.05) and surface hydrophobicity of DMPs with increasing of H2O2 concentrations (0–12 mmol/L). In contrast, the free thiol content (p < 0.05) and water retention ability of DMPs decreased with increasing H2O2 concentrations (0–12 mmol/L). These physicochemical changes suggested that high concentrations of hydroxyl radicals significantly altered the biochemical structure of DMPs, which was not conducive to the formation of a gel mesh structure. Furthermore, the gel properties were reduced based on the significant decrease in the water holding capacity (p < 0.05) and increased transformation of immobilized water of the heat-induced gel to free water (p < 0.05). With the increase of H2O2 concentrations, secondary structure of proteins analysis results indicated α-helix content decreased significantly (p < 0.05), however, random coil content increased (p < 0.05). And more cross-linked myosin heavy chains were detected at higher H2O2 concentrations groups through immunoblot analysis (p < 0.05). Therefore, as H2O2 concentrations increased, the gel mesh structure became loose and porous, and the storage modulus and loss modulus values also decreased during heating. These results demonstrated that excessive oxidation led to explicit cross-linking of DMPs, which negatively affected the gel-forming ability of DMPs. Hence, when processing duck meat products, the oxidation level of meat gel products should be controlled, or suitable antioxidants should be added.

The aim of this study was to evaluate the changes of ultrasound-assisted thawing on lamb meat quality and differential metabolite profiles during refrigerated storage. Compared with flow water thawing (FW), pH, a*, C*, and sulfhydryl content of lamb were significantly increased, while L*, drip loss and cooking loss were significantly decreased after ultrasound-assisted thawing (UT). On day 1 (UT1 and FW1) and day 7 (UT7 and FW7) in the UT and FW groups, principal component analysis explained 42.22% and 39.25% of the total variance. In this study, 44 (UT1 and FW1) and 47 (UT7 and FW7) differentially expressed metabolites were identified, including amino acids, carbohydrates and their conjugates, nucleic acids, carbonyl compounds and others. The results of this study provide data to clarify the differences between UT and FW, and lay a foundation for the application of ultrasound-assisted thawing in the meat industry.

Beef production in Uruguay is based on pasture (~85%) or concentrate (~15%), resulting in differences in meat quality. The objective of this study was to compare the oxidative stability and color of beef from these two systems during refrigerated retail display. For these purposes, the Semimembranosus muscle was removed from ten Aberdeen Angus steers raised and fed on pasture (130 days prior to slaughter) and from another ten steers fed concentrate (100 days prior to slaughter), sliced. The muscles were placed in a refrigerated showcase for 3, 6, and 9 days. The contents of β-carotene, α-tocopherol, and fatty acids were determined before the meat was placed on display. Lipid and protein oxidation, color, and heme iron content were determined before and during display. The meat from pasture-fed steers had a lower intramuscular fat content (1.78 ± 0.15 vs. 4.52 ± 0.46), lower levels of monounsaturated fatty acids, a lower n-6/n-3 ratio, less lipid and protein oxidation, lower L* and a* values, and higher levels of α-linolenic acid, DHA, total n-3, β-carotene, and α-tocopherol. In conclusion, the meat from pasture-fed steers was more stable during retail display from an oxidative point of view, which may be due to its higher levels of antioxidant compounds such as β-carotene and α-tocopherol and had a healthier fatty acid profile for consumers.

The aim of this study was to investigate the biochemical properties and gel-forming capacity of duck myofibrillar proteins under the effects of 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-mediated oxidation. Duck myofibrillar proteins were extracted and treated with different concentrations of AAPH solutions (0, 1, 3, 5, 10 mmol/L) and then analysed for carbonyl content, dynamic rheology, protein profiles and gel-forming properties (colour, water holding capacity, gel strength and microstructure). The results showed that with increasing AAPH concentration, the carbonyl content of the proteins exhibited an increasing trend (p < 0.05); SDS-PAGE pattern changes indicated that moderate oxidation (3 mmol/L AAPH) induced myosin aggregation via covalent bonds including disulfide, enhanced protein–protein interactions, and thus affected the gel strength of the DMPs’ heat-induced gels. However, high oxidation (5 and 10 mmol/L AAPH) led to the partial degradation of the myosin heavy chain (MHC) isoforms, as evidenced by lower storage modulus and irregular microstructures, which significantly reduced gelation ability. These results suggest that the internal relationship between alkylperoxyl radical-induced oxidation should be taken into account in the processing of duck meat, as mild protein oxidation is conducive to improving gel quality.

The presence of magnetic nanoparticles (MNPs) suppresses ice nucleation and growth during freezing and thawing. In this study, the effects of MNPs-assisted cryogenic freezing integrated with MNP-combined microwave thawing (NNMT) on the thermodynamic and quality changes of salmon fillets were investigated. Results have shown that NNMT raises Tg (glass transition temperature) and Tmax (transition temperature), thus improving the storage stability of salmon fillets. MNPs-assisted freezing and thawing treatment, especially NNMT treatment, significantly improved the water holding capacity, texture, color, and other quality characteristics of salmon fillets. In addition, the lipid and protein oxidation degrees of the NNMT treatment were the lowest, while the myofibrillar protein solubility of NNMT was the highest (87.28%). This study demonstrated that NNMT has minimal impact on the freezing–thawing quality of salmon fillets, making it a more suitable option for the preservation of aquatic foods.

In order to clarify the individual role of freezing and frozen storage on the quality of fish, fillets of large-mouth bass (Micropterus salmoides) were subjected to different freezing rates (freezing with −18 °C (A), −60 °C (B), and −60 °C with forced air circulation at 2 m/s (C), respectively) followed by frozen storage at −18 °C for 30 and 90 days. Another two groups were frozen at −60 °C, followed by storage at −40 °C (D) and −60 °C (E), respectively. Results showed that water-holding and TVBN were mainly affected by storage time. No significant changes were found in free thiol content among treatments. A greater freezing rate and lower storage temperature generally led to lower TBARS. GC × GC-TOFMS revealed a total of 66 volatile compounds, which were related to lipid oxidation. PLS-DA showed that fresh samples were separated from the frozen–thawed ones, and fillets in groups D and E were relatively close to fresh fillets in the composition of oxidation-related volatiles. In conclusion, freezing rate and storage temperature had a significant impact on lipid oxidation and protein denaturation in the fillets of large-mouth bass, while protein oxidation was more affected by freezing rate.

Soybean meal (SBM) is a premier source of protein for feeding food-producing animals. However, its nutritional value can be compromised by protein oxidation. In this study, a total of 54 sources of solvent extracted SBM (SSBM) and eight sources of mechanically extracted SBM (MSBM), collected from different commercial producers and geographic locations in the United States during the years 2020 and 2021, were examined by chemometric analysis to determine the extent of protein oxidation and its correlation with soybean oil extraction methods and non-protein components. The results showed substantial differences between SSBM and MSBM in the proximate analysis composition, protein carbonyl content, lipidic aldehydes, and antioxidants, as well as subtle differences between 2020 SSBM and 2021 SSBM samples in protein oxidation and moisture content. Correlation analysis further showed positive correlations between protein carbonyl content and multiple lipid parameters, including the ether extract, p-anisidine value, individual aldehydes, and total aldehydes. Among the antioxidants in SBM, negative correlations with protein carbonyl content were observed for total phenolic content and isoflavone glycoside concentrations, but not for Trolox equivalent antioxidant capacity (TEAC), α-tocopherol, and γ-tocopherol. Overall, soybean oil extraction methods, together with other factors such as enzyme treatment and environmental conditions, can significantly affect the proximate analysis composition, the protein and lipid oxidation status, and the antioxidant profile of SBM. Lipidic aldehydes and phenolic antioxidants play counteracting roles in the oxidation of soy protein. The range of protein carbonyl content measured in this study could serve as a reference to evaluate the protein quality of SBM from various sources used in animal feed.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: This study was designed to evaluate the effect of different cooking methods on the protein digestion characteristics of channel fish (Ietalurus punetaus). The channel fish muscles were subjected to different cooking methods, namely boiling, steaming and roasting and were subjected to in vitro gastrointestinal digestion simulation using raw fish as a control. All the cooking methods increased the protein digestibility (1.60–8.28%) and decreased the protein particle size at the end of the gastrointestinal digestion. The highest protein digestibility (66.78%) and the smallest protein particle size values (600.7 nm) were observed for the steamed group. Samples which were steam cooked showed lowest β‐sheet content (9.63 ± 0.81%) and were accompanied with moderate protein oxidation. As the core temperature increased from 40°C to 90°C, protein oxidation increased significantly (P < 0.05) with the increase of carbonyl groups and Schiff bases and decrease of sulfhydryl groups in all cooked groups. Based on the results, steaming was recommended as the best methods of cooking channel fish for improved protein digestibility. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the antioxidant properties of pepper (Zanthoxylum bungeanum Maxim.) leaf (ZL) extract as a natural oxidative agent against lipid and protein oxidation during larou processing. The phenolic profile of the ZL extract was assessed by HPLC and the ZL extract exhibited high 2,2 diphenyl‐1‐picryl‐hydrazyl (DPPH) (0.46 ± 0.07 mg mL−1) and 2,‐2′‐azino‐di‐(3‐ethylbenzothiazoline sulfonic acid (ABTS) (0.38 ± 0.04 mg mL−1) radical scavenging activity. The lipid and protein oxidation of larou was evaluated during the whole process with 0.02%, 0.04%, and 0.06% ZL extracts. Results showed that larou incorporation with ZL extracts significantly delayed the formation of thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and peroxide values (POV), and carbonyls (P < 0.05). In contrast, the surface hydrophobicity and intrinsic tryptophan fluorescence intensity were decreased (P < 0.05). Meanwhile, we found that the deceleration of sulfhydryl and protein solubility loss was observed in a concentration‐dependent manner (P < 0.05). Moreover, owing to the inhibitory effect of ZL extracts on lipid and protein oxidation, the sensory qualities of larou were improved during processing with increasing concentrations of ZL extract. These results suggested that ZL extract has huge prospects for application in dry‐cured meat processing. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of different concentrations of sodium nitrite on the quality and protein oxidation of salted meat during 21 days of curing. The salted meat was treated with sodium nitrite at 50, 100, and 150 mg/kg for curing, and salted meat without sodium nitrite was used as a control. The results showed that in salted meat added with sodium nitrite, the carbonyl group, disulfide bond, dityrosine, surface hydrophobicity, and the transformation rate from α‐helix to β‐sheet were all significantly reduced, whereas the sulfhydryl group content of myofibrillar proteins was significantly increased compared to the control. Meanwhile, the total volatile basic nitrogen and aerobic plate content were significantly decreased, while both the pH and a* value were significantly increased with an increase in nitrite concentration compared to the control group. Importantly, this phenomenon was also observed in salted meat treated with low doses of sodium nitrite (50 mg/kg). In conclusion, the quality of salted beef can be improved by adding low‐dose sodium nitrite to inhibit protein oxidation during the curing process. Practical Application: A low dose of sodium nitrite inhibited the rate of α‐helix to β‐sheet transformation of myofibrillar proteins in salted meat, reducing the exposure of hydrophobic groups and decreasing the production of protein oxidation products and TVB‐N to improve the quality of salted meat. These results provided a theoretical basis and technical guidance for the application of low‐dose sodium nitrite in meat processing enterprises. [ABSTRACT FROM AUTHOR]

Clinostat is a device often used for applying microgravity analogs in gravitational biology studies. It can constantly change the direction of the gravity vector through clinorotation with the possibility of speed regulation. In the present study, the impact of clinorotation (speed of 30 rpm) was investigated on the cell growth, viability, oxidative damage, and antioxidant compounds in Anthemis gilanica cell line using a two-dimensional clinostat. Cell clones were obtained from putting a cell suspension (1 ml) on the solid MS medium supplemented with 1-naphthaleneacetic acid (NAA, 0.5 mg L−1) and 6-benzylaminopurine (BAP, 1.5 mg L−1). Then, a cell line clone was transferred to a liquid MS medium for proliferation. The optimum subculture time for the cell line was found to be 14–15 days, and the cell line showed higher fresh weight compared to the control. The cell line was exposed to clinorotation (30 rpm) for 3 and 7 days. Results showed the cell growth parameters are managed with the ROS level and accumulation of antioxidant compounds in a time-dependent manner. Clinorotation increased cell growth, viability, protein content, DPPH, and antioxidant power, especially after 7 days. The level of H2O2, MDA, and protein-carbonyl increased after 3 days of clinorotation and then did not change significantly after 7 days compared to the control. Comet assay showed the weak genotoxicity impact of clinorotation on DNA damage in A. gilanica, which may relate to induction of antioxidant compounds (phenol and flavonoid) and PAL activity, especially after 7 days. But anthocyanin content did not change between treatments. The results display the potential effect of clinorotation on enhancing antioxidant capacity against oxidative damage and maintaining cell growth. Key message: Cell line with a homogenous population of proliferating cells can prepare the proper situation to study various cell responses under microgravity. Improving of potential antioxidant by clinorotation mitigates oxidative damage in medicinal plant cells. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of white ginseng addition (1%, 1.5%, 2%, 2.5% and 3% of meat weight) on the physical and chemical properties of roast chickens. The parameters studied were basic characteristics (salting absorptivity, texture, shear force, pH and sensory evaluation), lipid and protein oxidation, volatile compounds and ginsenoside content. Headspace solid phase micro-extraction and gas chromatography-mass spectrometry (GC–MS) were used to identify the flavor compounds of samples. The changes in physical and chemical properties showed that white ginseng had a positive effect on the quality of roast chickens. The oxidation rate of lipid and protein decreased with the increase of white ginseng addition. In addition, the contents of Ginsenoside Rg1 (Rg1), Ginsenoside Re (Re) and Ginsenoside Rb1 (Rb1) in samples were 5.763 μg/g, 6.047 μg/g and 8.447 μg/g, respectively. Obtained data evidenced the possibility of improvement of the quality characteristics and enrichment of the flavor of roast chickens by adding white ginseng. [ABSTRACT FROM AUTHOR]

The inhibitory effect of guava leaf polyphenols (GLP) on advanced glycation end products (AGEs) of frozen chicken meatballs (−18 °C) and its possible inhibitory mechanism was investigated. Compared with control samples after freezing for 6 months, acidic value (AV), lipid peroxides, thiobarbituric acid reactive substance (TBARS), A294, A420, glyoxal (GO), Nε-carboxymethyl-lysine (CML), pentosidine, and fluorescent AGEs of chicken meatballs with GLP decreased by 11.1%, 22.3%, 19.5%, 4.30%, 8.66%, 8.27%, 4.80%, 20.5%, and 7.68%, respectively; while free sulfhydryl groups the content increased by 4.90%. Meanwhile, there was no significant difference between meatballs with GLP and TP in AV, A294, GO, and CML (p > 0.05). Correlation analysis indicated that GO, CML, pentosidine, and fluorescent AGEs positively correlated with AV, TBARS, A294, and A420, while GO, CML, pentosidine, and fluorescent AGEs negatively correlated with free sulfhydryl groups. These results manifested GLP could inhibit AGEs formation by inhibiting lipid oxidation, protein oxidation, and Maillard reaction. The possible inhibitory mechanism of GLP on the AGEs included scavenging free radicals, capturing dicarbonyl compounds, forming polyphenol–protein compounds, and reducing the formation of glucose. Therefore, the work demonstrated that the addition of plant polyphenols may be a promising method to inhibit AGEs formation in food. [ABSTRACT FROM AUTHOR]

(1) Background: The effects of protein oxidization induced by malondialdehyde (MDA), which was selected as a representative of lipid peroxidation products, on the structure and functional properties of walnut protein were investigated. (2) Methods: Walnut protein isolate was produced by alkali-soluble acid precipitation. The modification of walnut protein isolate was conducted by MDA solutions (0, 0.01, 0.1, 1, and 10 Mm), which were incubated in the dark for 24 h. (3) Results: Increased carbonyl content and the degradation of sulfhydryl groups indicated MDA-induced protein oxidization. The circular dichroism spectra revealed disruption of the ordered protein secondary structure. The change in the tertiary conformation of the MDA-treated protein was observed through intrinsic fluorescence. Small polypeptide chain scission was observed at low MDA concentrations (≤0.1 mM) and protein aggregation was observed at high MDA concentrations (>0.1 mM) using high-performance size exclusion chromatography. Oxidized protein solubility was reduced. Furthermore, the emulsification stability index, foam capacity, and foam stability of walnut proteins were increased after treatment with 0.1 mM of MDA. An excessive concentration of MDA (>0.1 mM) decreased emulsification and foaming properties. (4) Conclusions: These results show that MDA oxidation modified the structure of walnut protein and further affected its function, which should be taken into account in processing walnut protein products. [ABSTRACT FROM AUTHOR]

The aim of this work is to evaluate the effects of different washing times (zero (W0), one (W1), two (W2), and three (W3) times) on the physicochemical characteristics, gel property, and protein oxidation of silver carp surimi during 4 °C refrigeration. The results showed that the yield, types of fatty acids, redness (a*), total volatile basic nitrogen, and thiobarbituric acid reactive substances of the surimi tended to decrease, and the whiteness, pH, gel strength, and water retention tended to increase with the increase of washing times. Meanwhile, washing removed some fatty acids and the fatty acid species showed a decreasing trend. The FTIR spectra showed that washing did not change the functional group composition but changed the content of each group of the functional groups, while decreasing the proportion of β-sheet structures. Compared with the unwashed surimi, washing caused some of the immobilized water in the minced fish to be transferred to free water, and the water fluidity was enhanced. The washing enhanced the water holding capacity in the surimi gels, and the microstructure of the surimi gels was denser and delayed the protein oxidation during refrigeration. However, the difference between W2 and W3 surimi was not significant (p > 0.05). In practice, W2 can be used to produce surimi to improve its yield and reduce water consumption. [ABSTRACT FROM AUTHOR]

The development and intensification of tilapia farming depends on the manipulation of some physiological functions, such as the sexual inversion of larvae using a synthetic androgen (17α-methyltestosterone). This inversion, however, may represent a potential oxidative stress factor and cause damage to animals in the short, medium, and long term. Dietary supplementation of natural antioxidant compounds is an interesting alternative to combat such damage. To test this hypothesis, an experimental trial was carried out involving sexual inverted and non-inverted Nile tilapia fingerlings, both supplemented and not supplemented with a blend of organic acids and essential oils protected by microencapsulation. Animals were divided into four experimental groups: NI (non-inverted animals), I (sexual inverted animals), NI + M (non-inverted animals supplemented with microcapsules), and I + M (sexual inverted animals supplemented with microcapsules). Blood parameters (WBC - white blood cells; LY - lymphocytes; RBC - red blood cells; HGB - hemoglobin; HCT – hematocrit number; MCH - mean corpuscular hemoglobin; MCV - mean corpuscular volume and MCHC – mean corpuscular hemoglobin concentration), as well as oxidative stress markers (enzymatic activity of superoxide dismutase – SOD and catalase - CAT; and total antioxidant capacity - 2,2-diphenyl-1-picryl-hydrazyl (DPPH)) and gene expression (heat shock protein 70 kDa - HSP70) were evaluated. The HGB (p < 0.001) and HCT (p = 0.005) parameters were reduced beyond the recommended limits for the animals in group I. The MCV varied statistically between the groups (p < 0.001). However, all values were within the recommended range for the species, jointly indicating normocytic anemia in group I fingerlings at the time of collection. The activity of CAT and SOD, as well as DPPH differed statistically between the experimental groups (p < 0.001), with the lowest SOD and CAT activity, as well as the highest DPPH registered in animals supplemented with microcapsules. The expression of HSP70 was lower in I + MI animals (p < 0.001). The synergistic evaluation of the results indicates that animals sexual inverted during the larval stage have a lower total antioxidant capacity in the fingerling stage, which reflects a worsening in hematological and enzymatic parameters related to immunity; and that dietary supplementation with blend of organic acids and essential oils protected by microencapsulation is sufficient to improve the immunological response both in sexual inverted and non-inverted fingerlings. • Sexual inversion during the larvae stage reflects a worsening in hematological and enzymatic parameter. • Supplementation of microencapsulated organic acids is efficient to improve the immunological response in fingerlings. • Dietary supplementation of antioxidants in the microencapsulated form can neutralize ROS in fish. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lipid oxidation and protein oxidation occur side by side in meat. Here, the effect of malondialdehyde (MDA), the major product of lipid oxidation, on the digestibility of beef myofibrillar proteins (MP) was studied. MP samples were incubated with 0, 0.1, 0.3, 0.5, and 0.7 mM MDA at 4 °C for 12 h and then subjected to in vitro gastrointestinal digestion. The result showed that MDA remarkably reduced the digestibility of MP (p < 0.05). MDA treatments significantly increased carbonyl and Schiff base contents in MP (p < 0.05). The microstructure observed by atomic force microscopy showed that MDA treatments resulted in the aggregation of MP. Non-reducing and reducing electrophoresis suggested the aggregation was mainly caused by covalent bonds including disulfide bond and carbonyl–amine bond. Proteomics analysis proved that the myosin tail was the main target of MDA attack, meanwhile, lysine residues were the major modification sites. Taken together, the above results imply that MDA induces protein oxidation, aggregation, and blockage of hydrolysis sites, consequently leading to the decrease in both gastric and gastrointestinal digestibility of MP. [ABSTRACT FROM AUTHOR]

This research paper addresses the hypothesis that the optimum doses of a continuous type of ultraviolet (UV) light applied to the surface of lor (whey) cheese needs to be identified to maximize mould inactivation and shelf life while minimizing quality deterioration. Therefore, the mould inactivation, protein and lipid oxidation products, sensory and colour attributes of lor cheese subjected to different doses of UV light (1.617, 4.018, and 36.832 kJ/m2) in a continuous type of UV system were evaluated. UV treated samples presented mould counts lower than those of untreated ones. UV treatment at more than 4.018 kJ/m2 allowed around 0.7–2.7 log reductions on mould growth during storage. The increase in UV light dose caused significant increases in primary and secondary lipid oxidation products. In particular, the highest doses applied to the surface of cheese samples had the highest values of protein carbonyls, as well as lipid oxidation products. Strong positive correlations were recorded between lipid and protein oxidation markers. Exposure to the highest doses of UV light increased foreign flavour perception, probably due to the oxidative reactions. The results indicated that the application of UV light to the lor cheese surface allowed delaying mould growth during storage but extreme doses could induce lipid and protein oxidation reactions, leading to quality deterioration. [ABSTRACT FROM AUTHOR]

Effect of Amino Acid-Derived Chloramines on proMMP9 Although the above data indicate that the reaction of proMMP9 with HOCl is rapid, in biological systems, there is an abundance of alternative targets and, hence, the flux of HOCl to which proMMP9 might be exposed may be limited by competition with other materials. Subsequent experiments examined the activation of proMMP9 by HOCl at various molar excesses over the concentration of proMMP9 by reagent HOCl in both borate and HEPES-containing buffers (see Section 2). The presence of Met was not completely efficient at preventing activation, with low extents of proMMP9 activation still detected, suggesting that proMMP9 competes with Met, to a small extent, for the added HOCl, and is consistent with the very rapid reaction of HOCl with proMMP9. HEPES buffer; Figure S3: Effect of different molar excesses of pre-formed HEPES chloramines on proMMP9 activation as determined by cleavage of a pro-fluorescent peptide and determination of the consequent fluorescence; Figure S4: Effect of methionine added after 2 h on HOCl-mediated activation of proMMP9. Effect of Methionine on Activation of proMMP9 by HOCl To further examine the role of HOCl in activating proMMP9, experiments were carried out in the presence of methionine (Met) (1 mM), which reacts with HOCl with a high-rate constant ( I k i ~3 × 10 SP 7 sp M SP -1 sp s SP -1 sp [[45]]) to give the corresponding (unreactive) sulfoxide. [Extracted from the article]

However, urinary concentrations of pentosidine, one of the AGEs, were significantly higher in patients with acute exacerbation of AD than in healthy controls and patients with stable AD [[55]]. Study Group Twenty-one AD patients and 19 CU patients who were admitted to the local dermatology and allergology clinic of the Provincial Hospital No. 2, Rzeszow, Poland, were enrolled in a single-center cross-sectional study. Keywords: atopic dermatitis; chronic urticaria; lipid peroxidation; protein oxidation EN atopic dermatitis chronic urticaria lipid peroxidation protein oxidation N.PAG N.PAG 13 08/29/22 20220801 NES 220801 1. Additionally, the concentrations of nitrite and nitrate were lower, and the protein-bound nitrotyrosine content was significantly increased in the skin lesions in NC/Nga mice, an animal model for human AD that could suggest that reactive nitrogen species are involved in the pathogenesis of AD [[34]]. [Extracted from the article]

Wheat flour proteins are subject to oxidation reactions during production, processing and storage. The quality of protein and the rheological properties of wheat are crucial for the flour industry. However, the impact and mechanism of protein oxidised on wheat flour quality remain unclear. In this study, ozone was used to oxidise wheat grains, the secondary structure of protein in flour and the rheological properties of dough were analysed by FTIR and Mixolab. The proportion of α‐helix and β‐folding of protein were decreased significantly, as were the development time (DDT), stability time (DST) and protein weakening (C2) value of dough. Meanwhile, starch gelatinisation (C3), amylase activity (C4) and retrogradation (C5) were increased significantly, along with the elastic modulus (G′) and viscous modulus (G″). Microstructure analysis indicated that protein oxidation destroyed the gluten network structure in the dough. In addition, the L* value of dough was decreased and a* and b* values were increased significantly. The results showed that the oxidation of protein reduced the stability of protein secondary structure, weakened the structure and stability of the gluten network in dough, and changed the viscoelasticity and colour of dough. Overall, these findings provide a better understanding of rheological behaviour in wheat flour. [ABSTRACT FROM AUTHOR]

BACKGROUND: Soybean oil bodies (SOB) are naturally pre‐emulsified lipid droplets recovered directly from soybean seeds. Almost all food emulsions contain salts. However, it was not clear how the incorporation of salts affected the physicochemical stability of SOB. RESULTS: This study investigated the effect of NaCl (0–1.2%) on the physical and oxidative stability of SOB emulsions under neutral (pH 7) and acidic (pH 3) conditions. In the presence of NaCl, the SOB emulsion (pH 7) showed strong flocculation during storage due to electrostatic screening. The NaCl‐induced flocculation of SOB was attenuated at pH 3, which may be due to the difference in conformation or interaction of the protein interfaces covering SOB at different pH values. The increase in ionic strength or acid conditioning treatment resulted in a remarkable increase in the stability of SOB emulsions against coalescence. The confocal laser scanning microscopy images also confirmed the NaCl‐induced changes in the flocculation/coalescence properties of SOB. The oxidative behavior tests indicated that SOB emulsions containing NaCl were more susceptible to lipid oxidation but protein oxidation was inhibited due to electrostatic screening, which reduced pro‐oxidant accessibility of unadsorbed proteins in the emulsion. This oxidative behavior was attenuated at pH 3. CONCLUSION: The incorporation of NaCl significantly reduced the physical and oxidative stability of the SOB emulsion, and acidic pH mitigated NaCl‐induced flocculation and lipid oxidation of SOB. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The contamination of toxic heavy metals in meat production and processing can cause the oxidative deterioration of processed meat products. Aside from the possible mechanisms of toxic heavy metals on pro-oxidative reaction, little is known about the potential impacts of toxic heavy metal contamination on meat quality attributes within permitted maximum residual levels. Therefore, the objective of this study was to determine the influence of the intentional contamination of toxic heavy metals on the oxidative deterioration in ground pork models during aerobic display storage. Four types of toxic heavy metal salts (As2O3, CdCl2, K2Cr2O7, and Pb(NO3)2) were mixed with ground pork at two different levels (maximum residue limit and its half level), PVC-wrapped, and displayed in a 4 °C showcase equipped with continuous fluorescent natural white light (1400 l×, color temperature = 6500 K). The contamination of toxic heavy metals significantly decreased the redness of ground pork, and rapidly increased the hue angle. The contamination of Cd and Cr equivalent to maximum residue levels (0.05 and 1.0 mg/kg, respectively) could increase the formation of peroxides, 2-thiobarbituric acid reactive substances, and carbonyls, along with an immediate decrease in total reducing activity. However, there was no difference in protein thiol content between treatments (p > 0.05). These results indicate that contamination of certain toxic heavy metals, particularly Cd and Cr, would accelerate discoloration, lipid oxidation, and carbonyl formation of ground pork during aerobic storage. [ABSTRACT FROM AUTHOR]

BACKGROUND: The decline in poultry meat quality can occur due to the oxidation of lipids and proteins during the storage period. OBJECTIVES: This study aimed to evaluate the effects of using Alhagi maurorumin a broiler diet on the oxidation of the lipids and proteins of broiler breast fillets during frozen storage. METHODS: A total of 54 male 1-day-old Ross 308 broiler chickens were divided into three groups of basal diet as the control group and basal diet supplemented with 10 and 20 g/kg of A. maurorum fed for 42 days. After slaugh-ter, breast fillets were kept at -18℃ for 9 months and peroxide value (PV), thiobarbituric acid reactive substances (TBARS), protein carbonyl content, and organoleptic assays were performed on samples every 3 months. RESULTS: The PV, TBARS, and carbonyl content of both treatment groups at all time points of frozen storage were significantly lower than that of the control group. Statistically, no difference was found between the samples of the two supplemented groups. Moreover, the sensory evaluation revealed no significant difference between the treatment and control groups. CONCLUSIONS: According to the results of the present study, the incorporation of A. maurorum in broiler diets delayed lipid and protein oxidation in the breast meat.

In this study, the effect of L-arginine (L-Arg) on the oxidative aggregation of myofibrillar proteins (MPs) in Antarctic krill was evaluated. The results showed that the oxidized aggregation of MPs was significantly inhibited after the addition of 20 mM L-Arg compared to the oxidized group, the solubility of MPs significantly increased by 25.74 %, the turbidity reduced from 0.56 to 0.18. These effects were primarily attributed to the addition of L-Arg, which prevented the unfolding of the spatial structure of MPs after oxidation, inhibited the formation of disulfide bonds and dityrosine, and improved the stability of MPs structure. Analysis of carbonyl content and hydroxyl radical (•OH) inhibitory capacity showed that carbonyl formation and hydroxyl radicals were effectively reduced by the pH and guanidinium group of L-Arg. The pH of L-Arg exhibited a significantly higher effect than the guanidinium group in inhibiting the oxidative aggregation of MPs. [Display omitted] • L-Arg effectively inhibited the oxidative aggregation of MPs. • When the L-Arg concentration was 20 mM, the antioxidant effect was the best. • The oxidative inhibition of pH of L-Arg was superior to that of guanidinium group. [ABSTRACT FROM AUTHOR]

The study constructed a model of temperature fluctuation (TF, −20 °C ∼ -10 °C) during frozen status to build a link between the tilapia fillets muscle of ice crystal morphology, moisture distribution, protein oxidation index and the edible quality. When TF treatment more than 3 times, the brightness, color and hardness of frozen tilapia fillets decreased significantly, and the cooking loss and thawing loss increased significantly. The free and unconjugated water in frozen fish fillets exceeded 97 % and did not change much after 9 times TF. The K and TVB-N values were within the safety standards (K < 60 %, TVB- N < 30 mg N/100 g). The ice crystals in the tissues were significantly increased. Protein carbonyls and Ca2+-ATPase were significantly reduced, and secondary structures were irregular. Network correlation analysis showed that ice crystal morphology was significantly correlated with the color, texture and protein oxidation index of frozen tilapia fillets. The results would provide theoretical approach for the transportation and sales of tilapia industrial enterprises. • Tilapia fillets treated with cyclic fluctuation from −20 °C to −10 °C for 9 times are still edible. • The quality of fish fillets decreased significantly after 3 times treatments. • Enlargement of ice crystals is the main cause of protein oxidation. [ABSTRACT FROM AUTHOR]

Down syndrome (DS), trisomy of chromosome 21, is the most common genetic form of intellectual disability. The neuropathology of DS involves multiple molecular mechanisms, similar to AD, including the deposition of beta-amyloid (Aβ) into senile plaques and tau hyperphosphorylationg in neurofibrillary tangles. Interestingly, many genes encoded by chromosome 21, in addition to being primarily linked to amyloid-beta peptide (Aβ) pathology, are responsible for increased oxidative stress (OS) conditions that also result as a consequence of reduced antioxidant system efficiency. However, redox homeostasis is disturbed by overproduction of Aβ, which accumulates into plaques across the lifespan in DS as well as in AD, thus generating a vicious cycle that amplifies OS-induced intracellular changes. The present review describes the current literature that demonstrates the accumulation of oxidative damage in DS with a focus on the lipid peroxidation by-product, 4-hydroxy-2-nonenal (HNE). HNE reacts with proteins and can irreversibly impair their functions. We suggest that among different post-translational modifications, HNE-adducts on proteins accumulate in DS brain and play a crucial role in causing the impairment of glucose metabolism, neuronal trafficking, protein quality control and antioxidant response. We hypothesize that dysfunction of these specific pathways contribute to accelerated neurodegeneration associated with AD neuropathology.

This study aimed to investigate the effect of oxidized beef protein on colon health. C57BL/6 mice were fed diets containing in vitro oxidized beef protein (carbonyl content 5.83/9.02 nmol/mg protein) or normal beef protein (control group, carbonyl content 2.27 nmol/mg protein) for 10 weeks. Histological observations showed that oxidized beef protein diet induced notable inflammatory cell infiltrations in colon. The analysis of high-throughput sequencing indicated oxidized beef protein largely altered the composition of gut microbiota (GM) by increasing proinflammatory bacteria (Desulfovibrio, Bacteroides, Enterorhabdus) while reducing beneficial bacteria (Lactobacillus, Akkermansia). In addition, oxidized beef protein remarkably increased protein fermentation in the colon, which was evidenced by the elevated i-butyrate, i-valerate, and ammonia levels in feces. Furthermore, consuming oxidized beef protein destroyed colon barrier functions by decreasing tight junction proteins expression. These changes in colonic ecosystem activated the proinflammatory pathway of lipopolysaccharide/toll-like receptor-4/nuclear factor kappa B (LPS/TLR-4/NF-κB), eventually leading to colonic inflammatory damage in mice. Taken together, these results imply that consuming oxidized beef protein detrimentally regulates GM and impairs colon health.

Background. Insomnia occurs in more than half of menopausal women. These disorders can contribute to a change in the prooxidant-antioxidant balance, causing the damage to structural cellular elements. Currently, there is a lack of research on this issue.Aim. To carry out a comparative analysis of the level of advanced oxidation protein products in in periand postmenopausal women with insomnia.Materials and methods. The study included peri(n = 30) and postmenopausal (n = 60) women, who were divided into 2 groups (control and main groups) in each menopausal phase after being questioned using special sleep questionnaires: Insomnia Severity Index; Epworth Sleepiness Scale; Munich Chronotype Questionnaire. The advanced oxidation protein products (AOPP) levels was determined by immunoenzymatic assay using ImmunDiagnostik (German) kits on a BioTek EL×808 (USA) analyzer. Statistical analysis was performed using Mann – Whitney test.Results. Comparative analysis of the AOPP levels in control groups, depending on the menopausal periods, showed an increase in their levels in the postmenopausal period as compared to perimenopause (p < 0.05). When comparing the AOPP levels between the control and the main group in different menopausal periods, statistically significant differences were revealed only in the perimenopausal period towards a higher content in women with insomnia (p < 0.05). The presence of insomnia in postmenopausal women is accompanied by a higher AOPP levels as compared to the perimenopausal women (p < 0.05).Conclusion. The obtained results indicate the association between insomnia and oxidative proteins modification only in the perimenopausal period.

Egg yolk forms have several health and industrial applications, but their storage characteristics and gel mechanisms have not been thoroughly studied. In order to investigate the relationship between the changes in structure and properties of egg yolk gel and egg yolk powder during storage, in this paper, egg yolk powder was stored at 37 °C for 0, 1, 3, and 6 months in an accelerated storage experiment, and the influence of storage time on the gel properties of egg yolk powder was analyzed. The results showed that the contents of protein carbonylation and sulfhydryl in the yolk decreased gradually with the extension of storage time. Circular dichroism and fluorescence spectra showed that the ordered structure and structural stability of egg yolk proteins decreased gradually. Oxidation led to the formation of intermolecular crosslinking in the egg yolk proteins and oxidized aggregates, resulting in a decrease in surface hydrophobicity, which affected the gel properties of the egg yolk powder after rehydration, resulting in the phenomenon of lipid migration and gel degradation. The results provide a theoretical basis for improving egg yolk powder’s overall quality and storage stability.

In this study, cathepsin D was oxidized in vitro with different concentrations of H2O2, and the activity, structure, and extent of myofibrillar protein degradation by oxidized cathepsin D were evaluated. The sulfhydryl content of cathepsin D decreased to 9.20% after oxidation, while the carbonyl content increased to 100.06%. The β-sheet in the secondary structure altered due to oxidation as well. The changes in the intrinsic fluorescence and UV absorption spectra indicated that oxidation could cause swelling and aggregation of cathepsin D molecules. The structure of cathepsin D could change its activity, and the activity was highest under 1 mM H2O2. Cathepsin D could degrade myofibrillar proteins in different treatment groups, and the degree of degradation is various. Therefore, this study could provide a scientific basis for the mechanism of interaction among hydroxyl radical oxidation, cathepsin D, and MP degradation.

Salted eggs are normally produced by treating fresh duck eggs with a high salt concentration in order to acquire distinctive features and excellent preservation capabilities as a result of a series of physicochemical changes. This method, however, induces a high salt content in the product. The goal of this research was to create a new way of producing mildly salted duck eggs using ozonized brine salting. The brine was made by dissolving NaCl (26% w/v) in water or ozonized water at a concentration of 50 ng ozone/mL (ozonized brine). Compared to brine, ozonized brine resulted in salted eggs with reduced ultimate salt levels in both albumen and yolk (p < 0.05). The Haugh unit of the salted eggs generated by ozonized brine was similar to that of the brine-made salted egg group (p > 0.05), but the salted egg produced by ozonized brine matured and solidified faster because the yolk index (0.62) was higher than that of the brine (0.55) (p < 0.05). The final pH of salted eggs generated with brine and ozonized brine was not different (p > 0.05). Regardless of the salting method, both salted eggs contained low TVB-N content (p > 0.05), and the value was extremely low (~0.1 mg MDA equivalent/kg). The TBARS value of the salted yolk prepared with brine was higher than that of the salted yolk prepared with ozonized brine (p < 0.05), and both salted yolks showed increased TBARS values after cooking (p < 0.05). The albumen and yolk components appeared to be altered similarly by both brine and ozonized brine, according to the FTIR spectra. Furthermore, the appearance and color of the yolk and albumen in salted eggs prepared with brine and ozonized brine were comparable. Boiled salted albumen produced with ozonized brine had a denser structure with fewer voids. This could be attributed to the final salted egg’s lower salt content and lower salt diffusion rate, which were likely caused by protein oxidation and, as a result, aggregation when ozonized brine was used.

In the present study, it was investigated if glucose addition (3 or 5%) to pork stimulates glycoxidation (pentosidine, PEN), glycation (Maillard reaction products, MRP), lipid oxidation (4-hydroxy-2-nonenal, 4-HNE; hexanal, HEX; thiobarbituric acid reactive substances, TBARS), and protein oxidation (protein carbonyl compounds, PCC) during various heating conditions and subsequent in vitro gastrointestinal digestion. An increase in protein-bound PEN level was observed during meat digestion, which was significantly stimulated by glucose addition (up to 3.3-fold) and longer oven-heating time (up to 2.5-fold) of the meat. These changes were accompanied by the distinct formation of MRP during heating and digestion of the meats. Remarkably, stimulated glyc(oxid)ation was accompanied by increased protein oxidation, whereas lipid oxidation was decreased, indicating these reactions are interrelated during gastrointestinal digestion of meat. Glucose addition generally didn't affect these oxidative reactions when pork was packed preventing air exposure and oven-heated until a core temperature of 75 °C was reached. [Display omitted] • Pentosidine content increased following gastrointestinal digestion of heated pork. • Glucose and long heating stimulated pentosidine levels in pork (digests). • High pentosidine levels were accompanied by low lipid- but high protein oxidation. • Low pentosidine levels in digests were seen when meat was packed and mildly heated. [ABSTRACT FROM AUTHOR]

The science of pet food processing is an emerging area of interest for many companion animal scientists. Pet food science has an essential role in ensuring the health and well-being of companion animals, and in the sustainability and viability of the animal agriculture industry. Many ingredients used in pet foods are co-products of human food production. Meat products, including whole meats, mechanically deboned meat, and rendered protein meals, are often used as a principal source of highly digestible, wellbalanced proteins and, vitamins and minerals. These products are transported, stored, and processed under various means. Many of these processes can have a detrimental impact on the nutrient and functionality of the protein component. Proteins are susceptible to many changes during processing that can impact their functionality, nutritional quality, and digestibility - including oxidative degradation. Oxidation of proteins is critical to understand as it can affect the functionality and quality of the diet. However, protein oxidation, from exposure to oxygen, heat, and light, has often not been well explored. Oxidized proteins may lead to reduced palatability, decreased digestibility, and other aspects of product quality of pet foods. Understanding protein oxidation mechanisms and their impact on product quality can help develop effective mitigation strategies for producing and maintaining high-quality pet food. There is a need for ongoing work to identify antioxidants, processing techniques, and storage conditions that minimize protein oxidation. Another critical need for the industry is to educate future pet food scientists to answer new problems and capitalize on innovative solutions. However, despite the growing demand for high-quality pet food, there remains a gap in specialized education for aspiring pet food professionals. Traditional animal science programs often lack dedicated coursework on companion animal nutrition and formulation, specifically pet food processing. On both the science of processing and the education of the next generation of scientists and industry professionals, there is a need to continue to draw on perspectives from the human food industry. As the pet food industry continues to evolve, it faces several challenges related to product quality, innovation, and the need for scientists who understand the pet food industry. [ABSTRACT FROM AUTHOR]