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Abstract: Cationic elastin-like polypeptides (CELP) are thermally responsive polypeptides that undergo an inverse temperature phase transition, and the recombinant CELP fusion proteins may be purified by inverse transition cycling (ITC). To obtain high-purity antimicrobial peptide cecropin AD (CAD), CELP was placed at the N-terminus of CAD and the expression vector pET28a-CELP-CAD was constructed. The expression vector was then transformed into Escherichia coli BL21 (DE3) to express the recombinant protein. After three rounds of ITC, enterokinase digestion and another hot spin, 1.2mg recombinant CAD was purified from 100ml culture medium. The antimicrobial test indicated that the high-purity CAD had strong antimicrobial activity against E. coli and Staphylococcus aureus. [Copyright &y& Elsevier]

Non-meat proteins are widely used in the meat processing, and the final product is greatly affected by salt. This study presented the combined use of soybean protein isolate (SPI) and egg white (EW) on the gelation of chicken myofibrillar protein (MP) with or with NaCl. Gel properties were determined with the use of texture profile analysis, cooking loss, intermolecular forces, rheological properties, scanning electron microscopy and low field nuclear magnetic resonance (LF-NMR) measurements. Non-meat proteins improved the MP gel quality when it was without NaCl, except for the increased cooking loss caused by 1.2% SPI. The effect of non-meat proteins on MP gel quality was more obvious at 0.3 mol/L NaCl, including the improvement of gel hardness by SPI and the reduction of cooking loss by EW. When the added non-meat proteins changed from 1.2% SPI to 0.3% EW-0.9% SPI, the gel hardness significantly decreased (P < 0.05). Its storage modulus was even lower than that of the pure MP, and uneven protein aggregates and pores were observed in the microstructure. This was because the SPI aggregates were wrapped by EW, and the SPI-EW aggregates led to the local aggregation of MP and the uneven structure of MP gel. • Soybean protein isolates (SPI) were wrapped by egg white (EW) forming aggregates. • The SPI-EW aggregates caused the local aggregation of myofibrillar protein (MP). • The combined utilization of SPI and EW improved the MP gel quality. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the physicochemical stability and potential gastrointestinal fate of the lutein-enriched high internal phase emulsions (LE-HIPE) stabilized by egg yolk-modified starch complex. Results showed that the physical stability and lutein retention of the LF-HIPE stabilized by egg yolk-hydroxypropyl distarch phosphate (EY-HPDSP) or egg yolk-octenyl succinic anhydride starch (EY-OSA) complex were both significantly improved at 4 °C. However, the LE-HIPE stabilized by EY-HPDSP complex showed better physical stability, lower lipid oxidation and higher lutein retention during storage at 37 °C than that stabilized by EY-OSA complex, which was related with the results of smaller droplets, more restricted water and oil protons for the former. In vitro digestion results showed that high level of HPDSP in LE-HIPE was beneficial to the improvement of the bioaccessibility of lutein. These results could be useful in the development of nutrient delivery system based on egg yolk-modified starch complex stabilized HIPE. [Display omitted] • HIPE protected lutein from chemical degradation during storage. • The physicochemical stability of EY-HPDSP was higher than that of EY-OSA. • The bioaccessibility of lutein was related to the particle size of LE-HIPE. [ABSTRACT FROM AUTHOR]

The effects of sodium tripolyphosphate and sugar on cold-set gel properties of egg yolk/κ-carrageenan/xanthan gum mixed dispersions were investigated by zeta potential, rheological measurements, gel textural analysis and low-field nuclear magnetic resonance (LF-NMR). As the yolk content increased to the 5 g/100 mL in aqueous systems, phase separation of mixed gel could be observed, due to the relatively rough gel appearance. Furthermore, the addition of phosphate could significantly improve the phase separation of mixed gels by elevating the pH and reducing zeta potential. The increase in the content of yolk and sugar brought an enhancement in gel storage modulus, while the addition of phosphate induced a dramatic decrease in the gelation rate of mixed gels. Textural analysis confirmed that hydrogen bonding interaction was the important force, which determined gel strength of the ternary composite cold-set gelation system. The result of LF-NMR revealed that there was a negative correlation between the decrease of proton mobility of immobilization water and the increase of gel strength in different sample series. • The phase separation of composite gels could be improved by polyphosphate. • Changes in G′ and hardness of composite gels depend on the hydrogen bonds. • Gel strength has a strong relation with the proton mobility of composite gels. [ABSTRACT FROM AUTHOR]

An 8-week trial was conducted to evaluate the effect of dietary β-glucan supplement (0, 0.01%, 0.02%, or 0.04%) on growth and health of Pacific white shrimp Litopenaeus vannamei at low salinity of 3 practical salinity unit (psu). The L. vannamei fed 0.02% and 0.04% β-glucan gained more weight and showed higher activities of protease, amylase, superoxide dismutase, and glutathione peroxidase in the intestine than in the control (0% β-glucan). The L. vannamei fed 0.04% β-glucan had a higher condition factor than those fed the control diet. Amylase activity in the hepatopancreas of L. vannamei fed 0.02% β-glucan was higher than those fed the control diet. Dietary β-glucan supplement increased the mRNA expressions of Toll-like receptor, myostatin, immune deficiency or heat shock protein 70, but decreased the mRNA expressions of tumor necrosis factor-α and C-type lectin 3 in both hepatopancreas and intestine. The response of intestine microbiota in L. vannamei fed 0.04% β-glucan was further compared to the control. The 0.04% β-glucan supplement reduced richness and diversity of the intestinal microbial community as indicated by the low values of Chao1 estimator, ACE estimator, Simpson index and Shannon diversity index. Abundances of Bacillus , Chitinibacter , Geobacillus and Vibrio in the intestine increased, while Flavobacterium , Microbacterium and Mycobacterium decreased significantly in L. vannamei fed 0.04% β-glucan compared to the control. This study indicates that dietary β-glucan supplement at 0.02%–0.04% can significantly improve digestibility, antioxidant capacity and immunity in L. vannamei , and thus improve growth performance and survival at low salinity. These beneficial effects of β-glucan probably are related to the dominance of probiotics over potential pathogens in the intestine. • Dietary 0.02%–0.04% β-glucan improved L. vannamei growth under low salinity. • Dietary 0.02%–0.04% β-glucan enhanced shrimp capacity of digestion, antioxidant and immunity. • β-glucan shaped L.vannamei gut microbiota through increasing diversity and richness of probiotics. [ABSTRACT FROM AUTHOR]

The poor freeze-thaw stability of konjac glucomannan (KG) hydrogel will greatly affect its application in the frozen prepared foods. In this study, the filling effects of natural tapioca starch (TS) and corn starch (CS) on the properties of freeze-thaw KG hydrogel were evaluated. The addition of starches significantly improved the gel strength and water holding capacity and inhibited the freeze-induced syneresis of composite hydrogels, where CS is superior to TS. These beneficial effects could be the results of concurrent effects of the decrease of frequency dependence/freezing point, the formation of dense microstructure and the reinforced hydrogen bonds and hydrophobic interactions of composite hydrogels. The foregoing results suggested the potential feasibility of low-cost natural starches to improve the textural properties and freeze-thaw stability of KG hydrogels. • Strong interactions occurred between the konjac glucomannan and starches. • Addition of starch decreased the freezing-induced syneresis of composite gel. • Konjac glucomannan/starch composite gel exhibited well-arranged network structure. • Corn starch was superior to tapioca in improving the properties of the composite gel. [ABSTRACT FROM AUTHOR]

Hyperosmotic stress can adversely affect fish immunity, but little is known about the histological and transcriptomic responses of immune organs in fish in a hyperosmotic environment. This study evaluated the effects of long-term hypersaline conditions (16‰) on the growth, histology and transcriptomics of the two main immune organs, the spleen and head kidney, in Nile tilapia Oreochromis niloticus relative to those reared in freshwater for eight weeks. No differences in weight gain and specific growth rate were found between fish reared under these two salinities. Hyperosmotic stress induced a congestive or enlarged spleen. Platelet- and coagulation-related gene expression was significantly decreased in tilapia at 16‰. The red cell distribution width and value of the mean corpuscular hemoglobin were significantly greater in fish at 16‰ salinity than in control fish in freshwater. A large volume of melano-macrophages in the spleen and pigment deposition in both the spleen and head kidney were observed in the histological sections in fish at 16‰ salinity. Transmission electron microscopic results showed abnormal macrophages with deposition granules in the spleen and head kidney and more neutrophils in the head kidney of fish at 16‰ than in control fish. In total, 772 and 502 genes were annotated for significantly different expression in the spleen and head kidney, respectively, and corresponded to five and one significantly changed immune system pathways, respectively. The complement pathway in the spleen was significantly down-regulated at 16‰. This study indicates that long-term exposure of Nile tilapia to a hyperosmotic environment can induce splenomegaly, reduce coagulation function, enhance phagocytic activity and down-regulate the complement pathway in the spleen. The spleen is a more sensitive organ for immune responses to chronic ambient salinity stress than the head kidney in Nile tilapia. [ABSTRACT FROM AUTHOR]

The efficiency of egg white protein microparticle (EWPM) and pectin sol (PS) addition in blocking flow behavior of light mayonnaise was investigated in this study. The texture properties, color, microstructure and thermal resistance were also measured for better understanding of synergistic effect of EWPM and PS on characteristics of light mayonnaise. At ratio of 2:4 (in weight ratio of PS and EWPM), the sample showed higher viscosity and hardness, attributed to the formation of larger protein aggregates induced by repulsion between protein and pectin molecule. The speculation was verified through the microstructure of mayonnaise samples observed by laser light confocal microscope. With the amount of EWPM increased, the yellow value of light mayonnaise increased, but thermal resistance decreased. For EWPM-rich samples, moderate heat treatment can strengthen the interaction between particles, inducing the increase of viscosity. [ABSTRACT FROM AUTHOR]

The aim of this study was to fabricate dual-function antioxidant emulsifiers using natural ingredients. Catechin-dextran-egg white protein (EC-Dex-EWP) conjugates were prepared using a two-step method: (i) free radical grafting of dextran to EC; (ii) attachment of EC-Dex to EWP using the Maillard reaction. The total phenolic equivalent of the conjugates formed was 4.91 mg EC per gram of conjugate and the free amino content decreased by 19.2% compared to EWP. The formation of EC-Dex-EWP conjugates was confirmed by electrophoresis, infrared spectroscopy, and fluorescence spectroscopy. The interfacial tension of the conjugates was higher than for pure proteins, which was attributed to their larger molecular weight and lower hydrophobicity that EWP. The conjugation of EC-Dex to EWP did not affect the solubility of the protein but it did improve its emulsifying properties. The thermal stability of proteins was improved through Maillard reaction. Moreover, the conjugates also exhibited a stronger antioxidant activity, which was attributed to the presence of polyphenols. Our results suggest that the protein-polysaccharide-polyphenol conjugates developed in this study have potential as novel surface-active antioxidants for improving the physicochemical stability of emulsion-based foods. • EC-Dex-EWP conjugates were prepared using a two-step method. • The formation of conjugates was confirmed by structural analysis. • Presence of dextran in conjugates improved their physical stability of emulsions. • EC provide a strong antioxidant activity for the conjugates. [ABSTRACT FROM AUTHOR]

Egg yolk powder is a widely used functional food ingredient due to its beneficial physicochemical and nutritional properties. However, its utilization in food can be limited due to its relatively high lipid content and low water-solubility. To address this issue, a two-step processing method utilizing enzymatic treatment combined with subcritical fluid extraction was investigated in this study. This method effectively reduced lipid content and improved water-solubility of egg yolk powder. An alcalase enzyme concentration of 500 U/g, extraction temperature of 313.15 K, extraction time of 120 min and a solid-liquid ratio of 1:9 (g:mL) produced powder with 20% lipid content and 71% water-solubility. Enzymatic hydrolysis clearly enhanced subcritical fluid extraction efficiency. This was attributed to hydrolysis disrupting the structure of egg yolk particles and facilitating the release of enclosed lipid molecules and was confirmed by scanning electron microscopy and laser confocal microscopy. [Display omitted] • Low-fat (20%) egg yolk powder with high water solubility (71%) was developed. • Enzymatic hydrolysis combined with subcritical fluid extraction was used. • Enzymatic hydrolysis improved the water solubility. • The highest oil extraction efficiency was achieved using 500 U/g alcalase. • Disruption in egg yolk structure promoted oil release. [ABSTRACT FROM AUTHOR]