Structure and functional properties of modified threadfin bream sarcoplasmic protein

Blue food proteins: Novel extraction technologies, properties, bioactivities and applications in foods

With the growing demand for healthy and sustainable food, blue food proteins have emerged as an important way to address resource-intensive production and environmental concerns. This paper systematically reviewed the extraction technologies, properties and bioactivities of blue food proteins and explored their wide range of applications. The novel extraction technologies not only improve the extraction efficiency of the proteins, shorten the production time and have environmental advantages, but also enhance the protein properties and facilitate subsequent applications. The amino acid composition of the blue food proteins is close to the FAO recommended standard and better than most of the livestock proteins, with excellent solubility and water holding capacity. Some of the proteins also have significant bioactivity and show great potential for improving health. Applications include emulsions, protein films, microcapsules, food colorants, dietary supplements, 3D printing materials, and cultured meat. This paper provides theoretical support for further research and application of blue food proteins and promotes their wider application in future food products.

Insights into Ultrasonication Treatment on the Characteristics of Cereal Proteins: Functionality, Conformational and Physicochemical Characteristics

BACKGROUND

It would be impossible to imagine a country where cereals and their byproducts were not at the peak of foodstuff systems as a source of food, fertilizer, or for fiber and fuel production. Moreover, the production of cereal proteins (CPs) has recently attracted the scientific community's interest due to the increasing demands for physical wellbeing and animal health. However, the nutritional and technological enhancements of CPs are needed to ameliorate their functional and structural properties. Ultrasonic technology is an emerging nonthermal method to change the functionality and conformational characteristics of CPs. Scope and approach: This article briefly discusses the effects of ultrasonication on the characteristics of CPs. The effects of ultrasonication on the solubility, emulsibility, foamability, surface-hydrophobicity, particle-size, conformational-structure, microstructural, enzymatic-hydrolysis, and digestive properties are summarized.

CONCLUSIONS

The results demonstrate that ultrasonication could be used to enhance the characteristics of CPs. Proper ultrasonic treatment could improve functionalities such as solubility, emulsibility, and foamability, and is a good method for altering protein structures (including surface hydrophobicity, sulfhydryl and disulfide bonds, particle size, secondary and tertiary structures, and microstructure). In addition, ultrasonic treatment could effectively promote the enzymolytic efficiency of CPs. Furthermore, the in vitro digestibility was enhanced after suitable sonication treatment. Therefore, ultrasonication technology is a useful method to modify cereal protein functionality and structure for the food industry.

Insight into ultrasound-assisted phosphorylation on the structural and emulsifying properties of goose liver protein

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.

Effect of Ultrasonic Pulses on the Functional Properties of Stickwater

Large volumes of waste are generated in the processing operations of the fishing industry. These effluents contain potentially useful proteins. However, it is necessary to concentrate them for utilization. The stickwater (SW) resulting from this operation was subjected to a protein-fractionation step, pH adjustment (acid + alkaline) and ultrasonic pulsing in order to aid in hydrolysis and evaluate its functional and nutritional properties. The protein fractions, as well as the protein hydrolysates present in the tail water, had a chemical composition of 54.85 ± 4.21 and 74.81 ± 3.89 protein (%), 0.8 ± 0.1 and 0.2 ± 0.015 fat (%), 7.21 ± 0.67% ash (%), respectively. The increase in low-molecular-weight peptides results in an increase in free-radical scavenging activity. However, the increase in ferric-reducing antioxidant power may be due to the HCl treatment performed by the company. An increase in the functional properties of the samples treated with ultrasonic pulses was observed. Therefore, the chemical, nutritional and functional characteristics of stickwater suggest its potential use as a food additive.

Antioxidant and antimicrobial material by grafting of L-arginine onto enzymatic poly(gallic acid)

Microwave-mediated grafting of L-Arg onto naturally derived and stable multiradical poly(gallic acid) (PGAL) in aqueous media has been successfully achieved. This polymeric material has no adverse effect in human cells as there is no hemolytic activity upon MTT and Neutral Red assays. The analytical and computational characterization studies carried out in this study describe a helical molecular structure with random incorporation of L-Arginine pendant groups from PGAL's backbone. The antioxidant properties of the precursor polymer are preserved as proved by the elimination of stable DPPH and hydroxyl radical scavenging, as well as the FRAP and ORAC assays. Regarding the latter, the oxygen radical inhibition is enhanced compared to PGAL, which is attributed to the guanidyl moieties. PGAL-g-L-Arg displays antimicrobial activity against Gram (+) Listeria monocytogenes and Staphylococcus aureus strains with a MIC of 0.8 g/L and a bacteriostatic effect against Gram (-) Escherichia coli. Additionally, scanning electron and confocal fluorescence microscopies as well as crystal violet colorimetric assay demonstrate that the mechanism involved in the bacterial inhibition is related to the formation of porous channels on the membrane, which is discussed according to the helical secondary structure of the polymer and the amino acid guanidyl moieties interacting to bacterial membranes.

Physicochemical and emulsifying properties of mussel water-soluble proteins as affected by lecithin concentration

The effects of lecithin addition at different concentrations (0-2.0%) on the physicochemical and emulsifying properties of mussel water-soluble proteins (MWP) were investigated. In solution system, low lecithin concentration (0.5%-1.0%) induced the aggregation and increased turbidity of composite particles. Lecithin addition caused changes in secondary structure and induced partial unfolding of MWP. Hydrophobic interactions between MWP and lecithin may contribute to the exposure of chromophores and hydrophobic groups of MWP. The interfacial tension decreased with lecithin addition. However, at a high lecithin concentration (1.5%-2.0%), the degree of aggregation and state of unfolding alleviated due to competitive adsorption. In emulsion system, with the low concentration of lecithin addition (0.5%-1.0%), droplet size and surface charge of emulsion decreased. The emulsion activity index, emulsion stability index, percentage of adsorbed protein increased. Both creaming stability and viscoelastic properties improved. At an intermediate lecithin concentration (1.0%), the emulsion showed the highest physical stability, while further addition of lecithin caused a slight deterioration in emulsifying properties. Overall, these results indicated the possibility that the lecithin-MWP mixed emulsifiers can be used to obtain emulsions with desirable properties.

Modifying the Physicochemical and Functional Properties of Water-soluble Protein from Mussels by High-pressure Homogenization Treatment

This study investigated the changes in physicochemical and functional properties of water-soluble protein from mussels (MWP) induced by high-pressure homogenization (HPH). The results indicated that HPH treatment unfolded or disrupted the initial structure of MWP, exposing free sulfhydryl groups and buried hydrophobic groups. As the homogenization pressure increased, the aggregation of MWP particles gradually decreased. Moreover, protein solubility and dispersion stability increased in aqueous solution. Foaming and emulsifying properties were also improved. HPH treatment has proven to be an effective technique for enhancing the functional properties of shellfish protein, and 120 MPa was the optimum homogenization pressure to modify MWP.

Surface Hydrophobicity and Functional Properties of Citric Acid Cross-Linked Whey Protein Isolate: The Impact of pH and Concentration of Citric Acid

The effects of citric acid-mediated cross-linking under non-acidic conditions on the surface hydrophobicity, solubility, emulsifying, and foaming properties of whey protein isolate (WPI) were investigated. In this research, citric acid-mediated cross-linking could not only increase the surface hydrophobicity of whey proteins at pH 7.0 and 8.0, but it also improved its emulsifying and foaming properties. The emulsifying activity and foaming ability of WPI reached a maximum under the condition of 1% citric acid and pH 7.0. However, the solubility of WPI-CA gradually decreased with pH and the content of citric acid increased. Therefore, the cross-linking mediated by citric acid under non-acidic aqueous conditions, markedly altered the surface hydrophobicity and enhanced emulsifying and foaming properties of WPI.

Chemical and Functional Characterization of Sarcoplasmic Proteins from Giant Squid (Dosidicus gigas) Mantle

Modification of pH and NaCl concentration changed the physicochemical properties of sarcoplasmic proteins (SP) from jumbo squid mantle and consequently their functional properties. Better results of emulsifying activity index (EAI) and foam capacity (FC) were exhibited at pH 11 in NaCl absence due to higher solubility. But better emulsifying stability index (ESI) was obtained at pH 11 in 0.5 M NaCl, while, foaming stability (FS) was better at pH near to isoelectric point (pI). These results suggest that SP from jumbo squid may be a promising ingredient, whose functional properties can be manipulated by changing pH and NaCl concentration.

Effects of pH-treated Fish Sarcoplasmic Proteins on the Functional Properties of Chicken Myofibrillar Protein Gel Mediated by Microbial Transglutaminase

pH adjustment would be of advantage in improving the water holding capacity of muscle proteins. The objective of this study was to evaluate the addition of fish sarcoplasmic protein (SP) solution, which was adjusted to pH 3.0 or 12.0, neutralized to pH 7.0, and lyophilized to obtain the acid- and alkaline-treated SP samples, on the functional properties of the chicken myofibrillar protein induced by microbial transglutaminase (MTG). The solubility of alkaline-treated SP was higher than that of the acid counterpart; however, those values of the two pH-treated samples were lower than that of normal SP (p<0.05). All SP solutions were mixed with myofibrillar proteins (MP) extracted from chicken breast, and incubated with MTG. The shear stresses of MP with acid- and alkaline-treated SP were higher than that of normal SP. The thermal stability of MP mixture reduced upon adding SP, regardless of the pH treatment. The breaking force of MP gels with acid-treated SP increased more than those of alkaline-treated SP, while normal SP showed the highest value. The MP gel lightness increased, but cooking loss reduced, with the addition of SP. Smooth microstructure of the gel surface was observed. These results indicated that adjusting the pH of SP improved the water holding capacity of chicken myofibrillar proteins induced by MTG.

Changes in physiochemical properties of water-soluble proteins from crucian carp (Carassius auratus) during heat treatment

In order to understand physicochemical properties of water-soluble proteins obtained from crucian carp, turbidity, total sulfhydryl content, hydrophobicity and SDS-PAGE of crucian carp water-soluble proteins during heat treatment were investigated. Turbidity remained unchanged up to 44°C and considerably increased from 46°C to 54°C, one peak of increase rate was found at 50°C; total SH content decreased rapidly when heated from 50°C to 55°C; hydrophobicity increased sharply when heated up to 45°C, indicating the conformation of water-soluble proteins from crucian carp began to unfold and expose the buried nonpolar amino acids at temperatures above 45°C; analysis of SDS-PAGE indicating the formation of disulfide linkage of creatine kinase and glyceraldehy-3-phosphate dehydrogenase when the temperature reached 65°C and 80°C, respectively.