Effect of limited enzymatic hydrolysis on structure and emulsifying properties of rice glutelin

Bioactive food derived peptides: a review on correlation between structure of bioactive peptides and their functional properties

The presence of bioactive peptides has already been reported in many foods such as milk, fermented products, plant and marine proteins. Bioactive peptides are sequences between 2 and 20 amino acids that can inhibit chronic diseases by modulating and improving physiological functions, so these peptides contribute in holding the consumer health. Also, bioactive peptides can affect pro-health or functional properties of food products. Fractionation of the protein hydrolysate revealed a direct relationship between their structure and functional activity. So, this review focuses on different factors effecting on bioactive peptide structures, biological and functional properties such as antihypertensive, antioxidative, hypocholesterolemic, water-holding capacity, foaming capacity, emulsifying properties and solubility. Also, this review looks at the identified bioactive peptides from food protein sources as potential ingredients of health promoting functional foods.

Comparing the binding interaction between β-lactoglobulin and flavonoids with different structure by multi-spectroscopy analysis and molecular docking

Four kinds of flavonoids (apigenin, naringenin, kaempferol, genistein) were skillfully selected to investigate the interaction between flavonoids and β-lactoglobulin (β-LG) by multi-spectroscopy analysis and molecular docking. Hydrogenation on C2C3 double bond weakened the affinity of apigenin for β-LG and it's most obvious, followed by hydroxylation of C3 and position isomerism of phenyl ring B. The main interaction force for apigenin and naringenin binding to β-LG (van der Waals forces and hydrogen bonds) was different from that of genistein and kaempferol (hydrophobic interactions). Circular dichroism and fluorescence experiments indicated that conformation of β-LG became loose and surface hydrophobicity of β-LG was reduced in the presence of flavonoids. Molecular docking indicated that flavonoids interacted with specific amino acid residues located on the outer surface of β-LG. These findings can provide a deep understanding about the interaction mechanism between flavonoids and protein, and it may be valuable in dairy incorporation with flavonoids.

Gelation kinetics and characterization of enzymatically enhanced fish scale gelatin-pectin coacervate

BACKGROUND

Protein-polysaccharide complex coacervations have been considered extensively for the development of functional foods. The main problem of the complex coacervates is that they are highly unstable under different conditions and that cross-linking is necessary to stabilize them. In this study, the effects of pectin at different concentrations on the gel and structural properties of fish scale gelatin (FSG)-high methoxyl citrus pectin (HMP) coacervate enhanced by microbial transglutaminase (MTGase) were studied.

RESULTS

The gelation rates and gel strength of the MTGase-enhanced FSG-HMP coacervate gels decreased with increasing HMP concentration. However, the enhanced coacervate gels exhibited better thermal behavior and mechanical properties compared with the original gels. Also, TG-P₈ exhibited the highest melting point (27.15 ± 0.12 °C), gelation point (15.65 ± 0.01 °C) and stress (15.36 ± 0.48 kPa) as HMP was 8 g kg^-1 . Particle size distribution, fluorescence emission and UV absorbance spectra indicated that MTGase and HMP could make FSG form large aggregates. Moreover, confocal laser scanning microscopy of treated coacervate gels showed a continuous protein phase at low HMP concentrations.

CONCLUSION

FSG and HMP could form soluble coacervate, and MTGase could improve the thermal and mechanical properties of coacervate gels. © 2017 Society of Chemical Industry.

Rheological behavior, emulsifying properties and structural characterization of phosphorylated fish gelatin

Rheological, microstructural and emulsifying properties of fish gelatin phosphorylated using sodium trimetaphosphate (STMP) were studied. Phosphorylation was carried out at 50 °C for 0, 0.5, 1 or 2 h. Rheological behaviors indicated that phosphorylation decreased gelation rate constant (k_gel) and apparent viscosity of gelatin solutions. Phosphorylation time was inversely proportional to tan δ; gelling and melting points of fish gelatin gels; however gel properties could be improved by short time of phosphorylation. Scanning electron microscopy and atomic force microscopy revealed that longer time of phosphorylation resulted in looser gel network with more aggregation. Longer phosphorylation time could stabilize fish gelatin emulsions, and endowed emulsions with smaller particle size and lower coefficient viscosity, but higher ζ-potential values. These results suggested that phosphorylation could be applied to obtain fish gelatin with varying functional properties suitable for numerous industrial applications.

Influence of hydrolysis behaviour and microfluidisation on the functionality and structural properties of collagen hydrolysates

The functionality and structural properties of pig skin hydrolysates with different degrees of hydrolysis (DH, 10% and 20%) and microfluidisation (120MPa), prepared by pepsin and Alcalase® have been investigated in this study. Extensive hydrolysis can significantly improve the absolute value of the zeta potential and surface hydrophobicity. The particle distribution of hydrolysates decreased with increasing DH. The numbers of free sulfhydryl (SH) and disulfide bonds (SS) were significantly increased with increasing DH (p<0.05). Hydrolysates with a lower DH showed a better emulsifying property than those with a higher DH. Microfluidisation led to the transformation of structural and interfacial properties of the hydrolysates and increased the value of the zeta potential, S₀, and gel strength. Microfluidisation results in limited breakage of chemical bonds, the number of SS and SH bonds unchanged in the treatment. These results reflect the functionality and structural properties of collagen-rich pig skin hydrolysates.

Enzyme-Based Strategies for Structuring Foods for Improved Functionality

Enzyme technologies can be used to create food dispersions with novel functional attributes using structural design principles. Enzymes that utilize food-grade proteins and/or polysaccharides as substrates have gained recent interest among food scientists. The utilization of enzymes for structuring foods is an ecologically and economically viable alternative to the utilization of chemical cross-linking and depolymerization agents. This review highlights recent progress in the use of enzymes to modify food structures, particularly the interfacial and/or bulk properties of food dispersions with special emphasis on commercially available enzymes. Cross-linking enzymes such as transglutaminase and laccase promote the formation of intra- and intermolecular bonds between biopolymers to improve stability and functionality, whereas various degrading enzymes such as proteases alter the native conformation of proteins, leading to self-assembly of hierarchically ordered colloids. Results of this bio-inspired approach show that rational use of structure-affecting enzymes may enable food manufacturers to produce food dispersions with improved physical, functional, textural, and optical properties.