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In this study, antioxidant peptides derived from sheep hemoglobin were prepared from fresh sheep blood. Sephadex G-25 chromatography, DEAE Sephadex A-50 chromatography, reverse phase high performance liquid chromatography (RP-HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to separate, purify, and identify peptides from the hydrolysate of sheep hemoglobin. The antioxidant activity of the obtained peptides was evaluated by their free radical scavenging capacity, stability against simulated gastrointestinal digestion and protective effect on H2O2-induced oxidative injury in Caco-2 cells. The results indicated that three novel antioxidant peptides, Ala-Tyr-Glu-Val-Asp (AYEVD), Phe-His-Thr-Met-Glu (FHTME) and Ser-Phe-Met-Tyr-Glu-Lys (SFMYEK), were purified and identified from the hydrolysate, with molecular masses of 595.60, 663.74 and 803.92 Da, respectively. Among them, AYEVD had the strongest scavenging capacity to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and AYEVD showed stronger antioxidant activity after simulated gastrointestinal digestion. In addition, AYEVD inhibited H2O2-induced oxidative injury in Caco-2 cells, significantly reduced the accumulation of reactive oxygen species (ROS), suppressed early cell apoptosis and the formation of malondialdehyde (MDA), and increased the activity of intracellular antioxidant enzymes. Therefore, this study could provide a theoretical basis for the application of novel antioxidant peptides from sheep hemoglobin in functional foods.

Oat β-glucan (OG) was used to replace salt in mutton mince at levels of 0%, 0.4%, 0.8%, 1.2% and 1.6%. To determine the appropriate level of OG replacement, the cooking loss, water-holding capacity (WHC), water distribution and content, color, gel strength, texture, secondary structure of myofibrillar protein, scanning electron micrograph (SEM) of mince samples with 2.0% salt, 0.4% OG + 1.6% salt, 0.8% OG + 1.2% salt, 1.2% OG + 0.8% salt and 1.6% OG + 0.4% salt were measured. The results showed that with increasing level of OG replacement, the cooking loss of mutton mince gels decreased first and then increased gradually, while the WHC showed the opposite trend. A significant decrease in the WHC was observed when 1.6% OG was added (P 0.05). The secondary structure of myofibrillar protein in the gel with high levels of OG replacement (> 0.8%) was similar to that in the control (P > 0.05), and the SEM image showed more loose structure with increased porosity. Through correlation analysis and principal component analysis (PCA), it was found that the synthetic score of the gel with 0.4% OG was higher than that of the other groups, which could ensure further reduction of salt intake while maintaining the gel quality of mutton mince.

This study aimed to assess the stability of thyme essential oil microcapsules (TEOMs) and their impacts on the antioxidant properties and quality of lamb patties. The results demonstrated that gum Arabic effectively enhanced the stability of phenols within the thyme essential oil (TEO), with an optimal core/wall ratio of 1:8. Substituting TEO with TEOMs in lamb patties led to reductions in the thiobarbituric acid content, carbonyl content, sulfhydryl loss, and protein cross-linking. Additionally, the TEOMs positively influenced the mutton patties' color, texture, microbiological stability, and sensory attributes. These findings substantiate the idea that TEOMs exhibit significant potential as a natural preservative to enhance the quality of mutton patties. [ABSTRACT FROM AUTHOR]

An improved screening procedure was developed for the detection of amino acid decarboxylase-positive microorganisms (especially lactic acid bacteria and Enterobacteria). Monolayer culture and double layer colour development methods for the detection of amino acid decarboxylase-positive lactic acid bacteria and Enterobacteria were established. Biogenic amine-positive bacteria strain was isolated directly from the samples. The applicability and detection level of the designed medium were quantitatively evaluated by the confirmation of the amine-forming capacity using an HPLC procedure, while tyrosine decarboxylase and lysine decarboxylase genes were detected by PCR with specific primers. The screening method showed a good correlation with the chemical analysis and molecular detection. Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Enterococcus faecium, and Enterococcus faecalis were obtained from traditional Chinese sausage. The isolation and screening of amino acid decarboxylase-positive lactic acid bacteria and Enterobacteria can be carried out simultaneously by the improved method.

Kazakh cheese is a traditional dairy product in Xinjiang, China. The function and potential probiotic characteristics of Saccharomyces cerevisiae DL6–20 and Kluyveromyces marxianus B13–5 in Kazakh cheese and its contribution to cheese fermentation was studied. In this study, the effect of the addition ratio of gamma aminobutyric acid (GABA)-producing S. cerevisiae DL6–20 and K. marxianus B13–5 on cheese quality was investigated. Cheeses were prepared by fermentations with a total of six treatments: comercial culture alone as control (CS), a combination with one yeast, either; K. marxianus B13–5 (CSM); S. cerevisiae DL6–20 (CSS); and three different proportions of this two yeasts (CSM:CSS 1:1, 1:2, 2:1). We measured the GABA content of cheese, as well as basic physical and chemical indicators, microbial content, free amino acid (FAA) content, texture, and flavor compound content. The total FAA content of mixed bacteria fermentation was higher than that of the single bacteria alone. The GABA content CSM:CSS 1:2 GABA content was 0.114 g/100 g, CSM:CSS 2:1 GABA content was 0.12 g/100 g, CSM:CSS1:1 content of GABA produced in the late ripening period of cheese was the highest, reaching 0.189 g/100 g and the number of LAB and yeasts in CSM:CSS 1:1 was higher than that of other cheeses. The mixed-strain fermentation generally produced cheeses with a higher protein content than that of the single-strain fermentation in the late stage of the maturation process, especially the protein content of CSM:CSS 1:1 during the ripening period, when the protein content was highest at day 50. CSM:CSS 1:1 had a low moisture content, making it easy to store. With the exception of water and protein content, there is no significant difference in other physical and chemical indicators. CSM:CSS 1:1 contributed to the formation of cheese texture. In addition, multivariate statistical analysis indicated that mixed-strain fermentation was beneficial to the production of cheese aroma, with the aroma production performance of CSM:CSS 1:2 and CSM:CSS 2:1 found to be better than that of CSM: CSS 1:1. [ABSTRACT FROM AUTHOR]

Vacuum-packed sauce lamb tripe was subjected to secondary pasteurization by high-pressure processing (HPP) and heat treatment (HT), and iTRAQ technology was applied to investigate the differentially expressed proteins (DEPs). The analysis revealed 484 and 398 DEPs in the HPP and HT samples, respectively, compared with no treatment. These DEPs were sorted by texture results, and it was revealed that these DEPs acted in different biological processes with many structural proteins and protein subunits related to lamb tripe texture. The results verified by Western blot were consistent with the protein expression changes observed by proteomics. The bioinformatics analysis showed that the hardness and gumminess of the sauce lamb tripe after HT might be related to changes in the expression of CNN1 and FN1. The changes in the expression of TMP, FN1, YWHAG, TTN, collagen isoforms, and ARPC3 might be related to the improved springiness and chewiness of lamb tripe after HPP. [ABSTRACT FROM AUTHOR]

We monitored the production process of Xinjiang dry‐cured mutton ham, and recorded changes in physicochemical and sensory quality such as appearance, texture, and aroma using E‐nose, texture profile analysis (TPA), and gas chromatography‐mass spectrometer (GC‐MS). During dry‐cured mutton ham processing, the moisture content decreased from 76% to 34%, while the NaCl content increased from 0.18% to 9.85%. Lipid oxidation was observed throughout the processing of dry‐cured mutton ham. Moreover, the nitrite content rapidly declined and reaching a minimum value of 1.58 mg/kg. During processing, the hardness of ham increased and its texture becomes tight, the chewability and gumminess improved over time. The muscle appeared rosy red, and the surface fat gradually became yellowish. Notably, seven classes of volatile compounds were identified among which aldehydes were the highest. Correlation analysis revealed that unsaturated fatty acids have a significant contribution to the composition of volatile compounds. PCA and cluster analysis results showed that the separation trend of the overall aroma profile of the dry‐cured mutton ham is obvious at different processing times. The quality of dry‐cured mutton ham changed the most during fermentation which was the key process stage of quality stabilization and improvement in the processing of dry‐cured mutton ham. These results provide information regarding the changes in aroma and quality of dry‐cured mutton ham during processing and are important for promoting the industrial processing of dry‐cured mutton ham. Practical applications: This study monitored the quality changes during the production of Xinjiang dry‐cured mutton ham. These results provide a basis for improving the quality of dry‐cured mutton ham and are important for promoting the industrial production of dry‐cured mutton ham. Developing high‐quality dry‐cured mutton ham will have a positive effect on promoting the added value of the mutton processing industry. [ABSTRACT FROM AUTHOR]

To investigated the mechanism of NaCl concentration on the production of putrescine in lactobacilli mf661779 and Escherichia coli mf661780. We explored the effect of NaCl concentration on the putrescine production mechanism in Lactobacillus delbrueckii MF661779 and Escherichia coli MF661780, both of which produce putrescine via the agmatine deiminase (AGDI) pathway. Reverse‐transcription quantitative PCR (RT‐qPCR) was used to analyse expression of AGDI pathway genes, and ultra‐performance liquid chromatography (UPLC) was used to monitor putrescine production over 48 hr. The results showed that NaCl had a lager inhibitory effect on the growth of E. coli MF661780, while NaCl affected the pH of L. delbrueckii MF661779 cultures to a greater extent. NaCl had minimal influence on expression of the transmembrane transcription activator aguR, but it markedly inhibited the transcription of the aguBDAC operon (p <.01). Differences in augB gene expression in L. delbrueckii at different NaCl concentrations were greater than in E. coli. Practical applications: In this research paper, we explored the effect of NaCl concentration on the putrescine production mechanism in Lactobacillus delbrueckii MF661779 and Escherichia coli MF661780, both of which produce putrescine via the agmatine deiminase (AGDI) pathway. NaCl had a lager inhibitory effect on the growth of E. coli MF661780, while NaCl affected the pH of L. delbrueckii MF661779 cultures to a greater extent. NaCl had minimal influence on expression of the transmembrane transcription activator aguR, but it markedly inhibited the transcription of the aguBDAC operon. This study was to determine the effects of NaCl on the putrescine production mechanism in L. delbrueckii and E. coli. According to the experiment, the research work is beneficial for evaluated the safety of fermented foods. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of starter cultures (Lactobacillus sakei and Staphylococcus xylosus) on lipid oxidation and accumulation of biogenic amines (BAs) in Chinese smoked horsemeat sausage. Physicochemical parameters, microorganisms, and sensory properties were assessed in smoked horsemeat sausage. Traditional microbiological detection and polymerase chain reaction‐denaturing gradient gel electrophoresis analysis showed that the starter cultures inhibited the growth of pathogenic bacteria in smoked horsemeat sausage during ripening. In addition, the starter cultures not only significantly reduced lipid oxidation, but also inhibited the accumulation of BAs (cadaverine, tyramine, putrescine, 2‐phenylethylamine, histamine, and tryptamine) in smoked horsemeat sausage. Sensory evaluation results showed that the starter cultures significantly improved the color, taste, odor, and overall acceptability scores of the smoked horsemeat sausage. Overall, the starter cultures were suitable for production of smoked horsemeat sausage with good organoleptic qualities. Practical applications: In China, smoked horsemeat sausage is one of the most popular traditional fermented sausage with a long history, but it is difficult to control quality during product fermentation. However, to the best of our knowledge, few studies exist on the effect of mixed starter cultures on smoked horsemeat sausage. This study strongly evidenced that the mixed starter cultures (Lactobacillus sakei and Staphylococcus xylosus) can significantly inhibit lipid oxidation and the accumulation of BAs in smoked horsemeat sausage, thereby improving product quality. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of crude peptide extract (CPE) from mutton ham on the lipid and protein oxidation of mutton patties during storage. Color indices, texture, and microbiological and sensory properties were assessed. The results showed that CPE addition significantly reduced thiobarbituric acid‐reactive substance levels, carbonyl content, sulfhydryl content loss, and protein cross‐linking in mutton patties; moreover, CPE improved their color, texture, and microbiological stability. Sensory evaluation results showed that CPE significantly improved the color, flavor, juiciness, texture, and overall acceptability scores of the patties. Overall, CPE was suitable for the production of mutton patties with good organoleptic qualities. Practical applications: In China, mutton patties are one of the most popular fast and convenient meat products. They are, however, prone to quality deterioration during storage. To the best of our knowledge, few studies have explored the effect of CPE from mutton ham on the antioxidant properties and quality of mutton patties. Herein, we report that CPE significantly inhibits the lipid and protein oxidation of mutton patties during storage, thereby improving product quality. [ABSTRACT FROM AUTHOR]

To determine antimicrobial resistance, 431 samples of retail foods purchased at different supermarkets in Northern Xinjiang were examined in this study. There were 112 Escherichia coli strains that were isolated, with approximately 26% of the samples contaminated by E. coli. The detection rate of E. coli isolated from pork was the highest (59.6%), followed by mutton (52.6%), retail fresh milk (52.4%), duck (36.4%), beef (35.3%), chicken (33.3%), and ready‐to‐eat food (12.9%); the E. coli detection rate for fish and vegetables was <11%. The result showed that the 112 isolates were mostly resistant to tetracycline (52%), followed by ampicillin (42%), compound trimethoprim/sulfamethoxazole (37%), amoxicillin (33%), and nalidixic acid (32%), imipenem resistance was not detected. One hundred isolates carried at least one antimicrobial resistance gene. The detection rate of resistance genes of our study was as follows: tetA (38%), tetB (27%), blaOXA (40%), blaTEM (20%), floR (20%), sul1 (16%), sul2 (27%), aadAla (19%), aadB (11%), strA (28%), and strB (24%); tetC and blaPSE were not detected. Virulence genes fimC, agg, stx2, fimA, fyuA, papA, stx1, and eaeA were found in 52, 34, 21, 19, 6, 3, 2, and 2 isolates, respectively; papC was not detected. There was a statistically significant association between fimC and resistance to ciprofloxacin (p =.001), gentamicin (p =.001), amikacin (p =.001), levofloxacin (p =.001), and streptomycin (p =.001); between fimA and resistance to tetracycline (p =.001), ampicillin (p =.001), compound trimethoprim/sulfamethoxazole (p =.001), and amoxicillin (p =.003); between agg and resistance to gentamicin (p =.001), tetracycline (p =.001), ciprofloxacin (p =.017), and levofloxacin (p =.001); and between stx2 and resistance to ampicillin (p =.001), tetracycline (p =.001), compound trimethoprim/sulfamethoxazole (p =.002), and amoxicillin (p =.015). [ABSTRACT FROM AUTHOR]

The purpose of this study was to prepare and characterize inclusion complexes between tea polyphenol (TP) and hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD), and to evaluate their antioxidant properties. Freeze‐drying was used to prepare the inclusion complex of TP/HP‐β‐CD at different component ratios (1:0.5, 1:1, and 1:2). The supermolecular structure of the TP/HP‐β‐CD complex was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Molecular docking was used to simulate the positions and interactions of the binding sites of TP/HP‐β‐CD inclusion complexes and target protein receptors. In addition, the effects of TP/HP‐β‐CD inclusion complexes on myofibrillar protein (MP) from lamb tripe were observed under oxidative conditions. Results showed that TP was encapsulated in the cavity of HP‐β‐CD to form an optimal complex with 1:2 molar ratio of stoichiometry, while the FTIR, TGA, and SEM studies also support the inclusion process. Molecular modeling results were systematically analyzed to determine the stability of inclusion complexes and protein. Furthermore, the addition of an appropriate concentration (5 to 105 µmol/g) of TP/HP‐β‐CD inclusion complex decreased the carbonyl content, hydrophobicity, and protein aggregation of MP from lamb tripe, whereas it increased the sulfhydryl content. This improved antioxidant activity and bioavailability of the inclusion complexes will be beneficial for its potential applications in food. Practical Application: Tea polyphenol was an antioxidant with potential for the field of food. In this study, the unstable properties of tea polyphenols were evaluated and were improved by inclusion of HP‐β‐cyclodextrin. The binding mode of the inclusion complex with protein was revealed via the molecular docking method, and the application of inclusion complex to control protein oxidation was studied. Results showed that the inclusion complex could effectively inhibit protein oxidation, which can provide a reference for the application of polyphenols in meat products and the improvement of protein properties. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of µ‐calpain oxidation on Coregonus peled myofibrillar protein degradation. In the present study, a hydroxyl radical oxidation system was selected to investigate oxidative modification on µ‐calpain activity and its degradation on C. peled myofibrillar protein. When subjected to oxidation, the carbonyl content of µ‐calpain significantly increased with the increasing of oxidation levels, and oxidation modification promoted the µ‐calpain activity. Incubation of C. peled myofibrillar protein with oxidized µ‐calpain resulted in the enhanced degradation of myosin heavy chains, actin, and troponin T, but the degradation of desmin at higher levels of oxidation was slightly inhibited, based on sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blotting. This study suggests that oxidation treatment of µ‐calpain could accelerate myofibrillar proteolysis through regulating the enzyme activity during postmortem aging. Practical Application: Endogenous proteases, especially µ‐calpain, are reported to be involved in fish softening during early postmortem storage, which is critical to muscle quality. The cysteine residues of proteins are particularly sensitive to oxidation. The investigation of the effect of oxidation on µ‐calpain (a cysteine protease) activity allows for the monitoring of its role in the postmortem proteolysis of fish myofibrils and the associated softening of fish meat, in an attempt to minimize this softening. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chinese mutton ham is a dry‐cured meat product with a long ripening time. The aim of this study was to identify and characterize antioxidant peptides from Chinese mutton ham. RESULTS: Mutton ham peptides (MHPs) were purified by gel filtration, anion exchange and reversed‐phase high‐performance liquid chromatography steps. The 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) free radical scavenging capacity was used to guide the purification of MHPs. Three antioxidant peptides were identified by liquid chromatography with tandem mass spectrometry (LC–MS/MS) as Met‐Trp‐Thr‐Asp (MWTD), Ala‐Pro‐Tyr‐Met‐Met (APYMM) and Phe‐Trp‐Ile‐Ile‐Glu (FWIIE), with molecular weights 551.61, 611.76, and 706.84 Da, respectively. Among them, APYMM exhibited the highest ABTS radical scavenging activity. The three peptides had the ability to inhibit lipid oxidation and Fenton's reagent‐induced protein oxidation and DNA damage. After simulated gastrointestinal digestion, FWIIE and APYMM showed increased antioxidant activity, while MWTD showed decreased activity. CONCLUSION: Three novel peptides isolated from Chinese mutton ham had strong biological activity. Chinese mutton ham is potentially a functional food and an excellent source of natural antioxidants. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim of this study is to identify the protein indicator of freshness of Coregonus peled using two‐dimensional gel electrophoresis (2‐DE) and matrix‐assisted laser desorption ionization‐time‐of‐flight/time‐of‐flight mass spectrometry (MALDI‐TOF/TOF MS) methods. Samples were obtained prior to (control group) and 2, 4, 6, and 8 days after refrigerated storage for quality and proteomics analysis. Three proteins were found to have significant differential abundance in sample groups during the refrigerated storage, including l‐lactate dehydrogenase, adenylate kinase isoenzyme 1, and myosin heavy chain, which were associated with freshness changes of C. peled. The freshness of C. peled fish during the refrigerated storage can be differentiated from the comparison of the specific proteins. Practical Application: The changes of food quality pose not only the relative economical loses but also the potential implications on consumer's health. Proteomics can represent a powerful tool to explore potential biomarkers that may be related to meat quality defects. The identification of key protein biomarkers linked to freshness of Coregonus peled allows to monitor the response of the food matrix during storage and try to minimizes these defects. [ABSTRACT FROM AUTHOR]

Summary: This study assessed the effect of ferulic acid on the accumulation of histamine in traditional Xinjiang smoked horsemeat sausage. The dynamics of histamine‐producing microorganisms were monitored by PCR‐denaturing gradient gel electrophoresis (DGGE) with specific primer pairs, and histidine and histamine levels were measured by high‐performance liquid chromatography (HPLC). Relative parameters including microbiological growth, pH and moisture content were also evaluated. PCR‐DGGE provided a rapid and convenient method for detecting and identifying histamine‐producing bacteria. The results showed that ferulic acid reduced the histamine concentration and inhibited the growth of histamine‐producing bacteria during fermentation and ripening. Additionally, the inhibitory effect of ferulic acid was stronger than that of the starter culture. Therefore, ferulic acid appears to be a useful additive for manufacturing fermented sausages. [ABSTRACT FROM AUTHOR]

Background Apolipoprotein B (APOB), and hepatic lipase (LIPC) genes have been shown to play a key role in lipid metabolism in type 2 diabetes (T2D). This study aimed to investigate the association of the three polymorphisms (rs679899 in APOB and rs6078 and rs6083 in LIPC) with T2D and related clinical quantitative traits. Methods We conducted a case-control study in Chinese Han population, with a total of 929 T2D patients and 1044 healthy subjects in Chinese Han population. Polymorphisms were genotyped by MassARRAY Genotyping System. Results The risk allele G of the polymorphism rs679899 was related to T2D (odds ratio (OR): 1.207, 95% confidence interval (CL): 1.006–1.448, P  = 0.043) and the polymorphism rs679899 was associated with glutamyl transpeptidase (GGT) levels ( P  = 0.001). We also showed that the polymorphism rs6083 was associated with cholesterol (CHOL) levels ( P  = 0.012), triglyceride (TG) levels ( P  = 0.040), and low-density lipoprotein cholesterol (LDL) levels ( P  = 0.033). No significant difference in genotypic frequencies of rs6078 and rs6083 was observed between T2D patients and controls. Conclusion This study suggests that the APOB polymorphism rs679899 is associated with type 2 diabetes and GGT levels, while the LIPC polymorphism rs6083 may influence CHOL, TG, and LDL levels in Chinese Han population. [ABSTRACT FROM AUTHOR]