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In this study, fermentation with Lactobacillus plantarum and Saccharomyces cerevisiae was applied to improve the flavor of cured duck leg meat. Odor and taste evaluations, lipid oxidation, volatile flavor substances, and protein degradation were determined to investigate the effects of microbial fermentation on flavor improvement. The results showed that the utilization of L. plantarum represented the most significant effect on lipid peroxidation inhibition (the lowest value of thiobarbituric acid reactive substances and the highest content of polyunsaturated fatty acids) and also enhanced the generation of volatile flavor substances than nonfermented duck meat. Microbial fermentation accelerated protein degradation in duck meat. S. cerevisiae could produce glutamate to promote the umami taste flavor of cured duck leg meat, and L. plantarum significantly improved the sweet taste by releasing alanine. Meanwhile, mixed fermentation with the two microbial species resulted in the combination of both of their advantages. These findings not only indicate the potential application of microbial fermentation in characteristic duck meat but also indicate that fermentation improves sensory properties of duck products significantly.

Jinhua ham is a popular traditional dry-cured meat product in China and South-east Asia and highly susceptible to quality deterioration during storage. Coating incorporated with black pepper essential oil was applied to suppress lipid deterioration and improve the aroma quality of Jinhua hams. Four treatments of without coating (CK), base formula coating (BC), BC + low concentration BPEO (0.05%) (LCBPEO) and BC + high concentration BPEO (0.1%) (HCBPEO) were used for the coating of hams. The samples were analyzed for lipolysis, lipid oxidation, volatile compounds and aroma sensory after 4 months of storage at room temperature. Results showed that HCBPEO decreased (p

The aim of this study was to elucidate the effect of ultrasound-assisted phosphorylation on the structural and emulsifying properties of goose liver protein (GLP), and GLP underwent different treatments (native (GLP-N), only ultrasound (UGLP), only phosphorylation (GLP-STP) and ultrasound-assisted phosphorylation (UGLP-STP)). UGLP-STP showed the highest phosphorylation degree of GLP among four groups; The FT-IR spectrum confirmed the phosphate group covalently attached to GLP in UGLP-STP. The highest hydrophobic capability and solubility were exhibited in UGLP-STP, resulting from the transformation of α-helix and β-turn into β-sheet and random coil. The treatment of UGLP-STP showed significantly higher values in emulsifying activity (32.24 ± 0.27 m2/g) and emulsifying stability (103.59 ± 2.40%) compared with other treatments. Confocal laser scanning microscopy suggested that UGLP-STP showed largest uniformity of particle distribution and smallest size than other groups. These results implied that ultrasonic-assisted phosphorylation showed a great improvement in emulsifying properties of goose liver protein.

The angiotensin-converting enzyme (ACE) inhibitory peptide LVLPGE provides outstanding antihypertensive effects in vivo, with a maximum systolic blood pressure (SBP) drop of 39 mmHg at a dose of 10 mg/kg. We evaluated the gastrointestinal digestion, transport, and in vivo antihypertensive effects of LVLPGE at different doses. LVLPGE was resistant to gastrointestinal enzymes with a stability of 97.8% and a permeability Papp of (5.09 ± 0.94) × 10-7 cm/s. LVLPGE was mainly transported through the Caco-2 cell monolayer by the peptide transporter PepT 1 and passive-mediated transport. LVLPGE at doses of 30 and 50 mg/kg had a positive antihypertensive effect in vivo; 30 mg/kg had a more significant effect than 50 mg/kg. After oral administration, the pharmacokinetics of LVLPGE showed that the Cmax was 4.65 ng/mL at 2 min. The blood pressure-lowering effect increased as the concentration of LVLPGE increased in the plasma of spontaneous hypertensive rats (SHRs).

This study was to investigate the effects of ultrasonic treatment on the physical and chemical properties of goose liver protein (GLP) and the anti-oxidative activity of the goose liver protein hydrolysate (GLPH). By measuring the average particle size, sulfhydryl and disulfide bond, secondary structure, hydroxyl radical inhibition, 1, 1-diphenyl-2-picrylhydrazyl radical scavenging rate, and ferrous ion chelating ability, we found that 300 and 600 W ultrasonic treatment reduced the particle size of GLP from 509.7 μm to 313.7 μm and 273.1 μm, respectively, and significantly decreased the content of sulfhydryl and the structures of α-helix and β-turn (p < .05). Meanwhile, the content of disulfide bond and β-sheet structure increased significantly (p < .05); the antioxidant capacity of GLPH increased significantly (p < .05). After 300 W ultrasonic treatment, the GLP in the enzymatic hydrolysis process was more conducive to the release of antioxidant substances compared with the 600 W ultrasonic-treated GLP. PRACTICAL APPLICATIONS: The physical and chemical properties of the GLP were changed by ultrasonic treatment, which was beneficial to improve the texture quality of goose liver paste and the anti-oxidative activity of GLPH. It could enhanced the functional characteristics of goose liver paste by enzymolysis. Meanwhile, antioxidant components extracted by ultrasonic treatment from goose liver could be added to foods as an excipient to improve the antioxidant properties.

In the present study we purified and identified peptides from broccoli protein hydrolysates and evaluated their angiotensin-converting enzyme (ACE) inhibitory activity in vitro and hypotensive effect in vivo. Three ACE inhibitory peptides were isolated and identified as IPPAYTK, LVLPGELAK, and TFQGPPHGIQVER, and their inhibitory IC50 values were 23.5, 184.0, and 3.4 μM, respectively. We then investigated the effect of gastrointestinal digestion on ACE inhibitory activity. We detected almost two times the ACE inhibitory activity of the peptide LVLPGELAK following simulated digestion than prior to digestion. LVLPGE and LAK, two novel peptides exhibiting high ACE inhibitory activity, were discovered following digestion and possessed IC50 values of 13.5 and 48.0 μM, respectively. The hypotensive effect of the peptides was assessed after oral administration to spontaneous hypertensive rats (SHRs). We found that LVLPGE and LAK demonstrated a significant hypotensive effect in vivo. Protein from broccoli may thus constitute a potential antihypertensive peptide source.

This work provided a new no-added-nitrite cured meat and an innovative method for substituting nitrite with Lactobacillus fermentum RC4 and Lactobacillus plantarum B6 as starters, beet red and Monascus color as coloring agents, and nisin as antibiotic. Three groups of cured meat were prepared: a no-added-nitrite experimental group (EG), a control group to which only salt was added (CG-S) and a control group to which both salt and nitrite were added (CG-N). After 20 days storage period at 18–20 °C, EG exhibited lower nitrite contents, better sensory characteristics, a greater content of free fatty acids, more volatile compounds, and more plate counts but without pathogenic bacteria compared to EG-S and CG-N. 3-hydroxy-2-butanone, 3-methyl-butanal, 2-methyl-butanal, 2, 4-heptadienal, heptanal, octanal and nonanal were the main flavor substances and palmitic acid, stearic acid, oleic acid, linoleic acid were main FFAs of EG. The no-added nitrite cured meat prepared by this novel method can improve the quality of cured meat and ensure low nitrite content.

To understand the taste of the Ruditapes philippinarum, 14 novel umami peptides were isolated and identified by gel chromatography, HPLC and UPLC-ESI-QTOF-MS/MS. Separations were combined with sensory evaluations and electronic tongue determinations. The peptide sequences were GRVSNCAA, SEEK, KEMQKN, KSAEN, QIEELEGK, TDVEQEGD, HNESQN, RGEPNND, TGDPEK, KGGGGP, TYLPVH, PAATIPE, GPAGPAGPR and AGAGPTP. All peptides had umami and umami-enhancing qualities, KSAEN and QIEELEGK had higher sensory evaluation than the others, while PAATIPE and HNESQN had the best umami-enhancing taste in a 0.35% MSG solution. Molecular docking of the peptides with T1R1/T1R3 indicated that Ser123, Ser146 and Tyr143 may be important in the interaction of the peptides with T1R3. Arg303, Ser123 and Asp166 appear to be involved in the synergistic effect of umami peptides combined with monosodium glutamate. The omission test and the addition test confirmed that the 14 umami peptides contributed to the umami taste of R. philippinarum.

Since Chinese Herbal Medicine contain many antimicrobial chemicals, they have great potential as new antimicrobial agents. Five Chinese Herbal Medicine extracts were obtained from hawthorn leaf, ginkgo leaf, bamboo leaf, redskin peanut, and lotus leaf by thermal reflux. The optimal mixed ratio was 2: 2: 5: 9 (hawthorn leaf, ginkgo leaf, bamboo leaf, redskin peanut) using the orthogonal method. The minimum inhibitory concentration (MIC) was 1.3 mg/mL. The total flavonoid content in the mixed-plant extract was 21.5%, and the quercetin, vitexin, different vitexin, galangal and resveratrol content were 0.32, 4.38, 1.87, 0.36 and 1.35 mg/L, respectively. The inhibitory mechanism was studied by changes in growth curves, cellular structure, cell-wall permeability and cell-membrane integrity. Results showed that the addition of plant extracts reduced the presence of E. coli, while increasing AKP, conductivity and ion-channel enzymes. Plant extracts damaged E. coli cell-walls and cell-membrane structures. The addition of 6% mixed-plant extract showed a positive effect on the quality and safety of fermented-bag sausage.

In this study, water-extractable arabinoxylan, WEAX, of wheat was isolated and mixed with gluten to observe small and large strain behavior and microscopic structure of the mixtures. The results showed that WEAX improves the viscoelasticity of gluten and makes the microscopic structure of gluten less compact. Free sulfhydryl, fluorescence anisotropy and CP/MAS 13C NMR measurements were used to gain a better understanding of the interactions between WEAX and gluten proteins of wheat. It was demonstrated that when gluten was mixed with WEAX, the free –SH of gluten proteins cross-linked to each other or to WEAX. The cross-linking happened mainly to LMW-GS. It was shown from the fluorescence anisotropy that the conformation of glutenin was more greatly influenced by WEAX than gliadin because of the difference in their molecular conformation. In addition, it was found in this study that tyrosine groups of glutenin also played an important role in the interactions between WEAX and gluten.

Nitrite helps meat products retain colour and prevents decay, but excessive intake can be carcinogenic. To investigate the mechanism of nitrite degradation by lactic acid bacteria, Lactobacillus fermentum RC4 were grown in broth containing NaNO2 at 0, 100, 300, or 500 mg/L, and 8-plex iTRAQ proteomics and bioinformatics analysis were employed to explore protein expression patterns during nitrite degradation. Real-time PCR was used to confirm mRNA expression levels of selected genes. In the 100, 300, and 500 mg/L sodium nitrite groups, 31, 87, and 190 differentially expressed proteins (DEPs) were identified, of which 24, 57, and 109 were up-regulated and 7, 30, and 81 were down-regulated. Gene ontology (GO) and Kyoto Encyclopaedia of genes and genomes (KEGG) analyses of DEPs indicated that adhE and lpdA involved in carbohydrate metabolism, cysK linked to amino acid metabolism, nirB related to nitrogen metabolism, fabI and accD associated with lipid metabolism, and gsk involved in nucleotide metabolism were dramatically differentially expressed. Nitrogen metabolism is essential for maintaining nitrogen balance, and the above genes appear to be involved in L. fermentum RC4 growth and development during nitrite reduction. These novel proteomics results provide new insight into the potential mechanism nitrite degradation by L. fermentum. Biological significance Nitrite helps meat products retain colour and prevents decay, but excessive intake can be carcinogenic. The probiotic L. fermentum RC4 can degrade nitrite but the mechanism is poorly understood. Herein, we performed quantitative proteomic profiling of L. fermentum RC4 using the iTRAQ approach, and identified various mechanisms potentially involved in nitrite degradation, including carbohydrate, amino acid, lipid, nucleotide, and nitrogen metabolic pathways. This is the first iTRAQ proteomic analysis of nitrite degradation by L. fermentum RC4, and the results provide novel insight.

Protein aggregation occurs in biological systems and industrial processes, affecting protein solubility and functional properties. In this study, whey protein isolate (WPI) obtained from bovine milk was used as a model to study the dependence of aggregation on pre-heating temperature and on protein and calcium concentrations. WPI solutions (0.1–5.0%, w/v) were heated at 25–85 °C for 30 min prior to cooling and calcium addition. Tryptophan shifted to a more hydrophilic environment as WPI concentrations and pre-heating temperatures increased. Pre-heated WPI solutions yielded soluble particles, which aggregated to form porous gel-like particles by addition of calcium chloride. WPI microgel particles could be prepared by using a cold gelation method and preheated the protein above 65 °C. The particle size was monodisperse with sizes of about 190 nm and 255 nm, respectively in solutions pre-heated to 75 or 85 °C and containing 5 m m calcium.

We have shown that bitter peptides derived from the hydrolysates of pepsin digested fish protein can increase lymphocytes and lysozyme activity and improve fish survival in aquaculture. In this study, we investigated how the immune function of bitter peptides increases the phagocytes’ engulf of latex beads, and analyzed the antioxidation of myofibrillar protein in peeled shrimp during chilled storage with /without bitter peptides by evaluating the activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and the effects of the total carbonyl and sulfhydryl. Also, the bitter peptides’ effect on the structural stability of muscles protein throughout oxidation was examined in vitro by both scanning electron microscope (SEM) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The engulf assay demonstrated phagocytosis increased from the control group to the highest bitter peptide concentration of 1.2 mg/ml; the bitter peptides had a significant DPPH radical-scavenging activity, reducing the power of ferric ions and metal chelating ability. Chemical analysis showed that myofibrillar protein in chilled storage was highly susceptible to oxidation, and the results indicate that treating peeled shrimp with bitter peptides before chilled storage significantly decreases the formation of carbonyl derivatives and reduces the loss of thiol groups when compared with the water treated sample. In addition, the results of both SEM and SDS-PAGE confirm that there was less distortion of tissue structure and less degradation of the protein in the samples treated with bitter peptides. Bitter peptides are both beneficial for fish disease control and preservation of marine food. Keywords: Bitter peptides, Myofibrillar protein, Antioxidation, Innate immunity, Scanning electronic microscopy (SEM)

We report the effects of protein from different duck products on the intestinal flora and physiology of rats. After 30 days of feeding, rats fed water–boiled salted duck protein had the lowest gut microbial diversity and richness. Allobaculum, Lactobacillus, Coprococcus and Eubacterium increased in rats fed wine-cured duck protein, while rats fed water–boiled salted and wine-cured duck protein showed increased serum urea (UREA) concentrations and serum cholesterol (CHOL) to HDL-cholesterol (HDL C) ratios, but decreased retroperitoneal white adipose tissue (rWAT) and perirenal white adipose tissue (pWAT) to body weight ratios. The changes in gut bacteria were mainly associated with the fat-mass index (weight of rWAT or pWAT to body weight ratio), accompanied by the opposite correlation with UREA content. Significance It showed that protein from different duck products impacted the intestinal flora and caused physiological changes in rats. Different sources of processed protein vary in their digestibility and digestive kinetics, all of which can affect the intestinal microbiota and physiology. We report the effects is an effort to map the complex interactions of “host physiology-nutrition-microbiota” in order to provide some insights into that food processing can be improved to promote beneficial gut microbes and enhance human health.