Effects of Baicalein and Chrysin on the Structure and Functional Properties of β-Lactoglobulin

Two flavonoids with similar structures, baicalein (Bai) and chrysin (Chr), were selected to investigate the interactions with β-lactoglobulin (BLG) and the influences on the structure and functional properties of BLG by multispectral methods combined with molecular docking and dynamic (MD) simulation techniques. The results of fluorescence quenching suggested that both Bai and Chr interacted with BLG to form complexes with the binding constant of the magnitude of 105 L·mol−1. The binding affinity between BLG and Bai was stronger than that of Chr due to more hydrogen bond formation in Bai–BLG binding. The existence of Bai or Chr induced a looser conformation of BLG, but Chr had a greater effect on the secondary structure of BLG. The surface hydrophobicity and free sulfhydryl group content of BLG lessened due to the presence of the two flavonoids. Molecular docking was performed at the binding site of Bai or Chr located in the surface of BLG, and hydrophobic interaction and hydrogen bond actuated the formation of the Bai/Chr–BLG complex. Molecular dynamics simulation verified that the combination of Chr and BLG decreased the stability of BLG, while Bai had little effect on it. Moreover, the foaming properties of BLG got better in the presence of the two flavonoids compounds and Bai improved its emulsification stability of the protein, but Chr had the opposite effect. This work provides a new idea for the development of novel dietary supplements using functional proteins as flavonoid delivery vectors.

Effects of High Hydrostatic Pressure Pretreatment on the Functional and Structural Properties of Rice Bran Protein Hydrolysates

Rice bran protein (RBP) hydrolysis was conducted after high hydrostatic pressure (HHP) pretreatment. The structural and functional properties of HHP-pretreated rice bran protein hydrolysates (RBPH) were investigated. HHP pretreatments were conducted at 100, 200, and 300 MPa; then, enzymatic hydrolysis at atmospheric pressure was performed using trypsin. An RBPH sample that had not been pretreated by HHP was used as a control. Free sulfhydryl (SH) content, SDS-PAGE profiles, high-performance size exclusion chromatography (HPSEC), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), intrinsic fluorescence spectrum, solubility, and emulsifying and foaming properties were evaluated. Changes in particle size and ζ-potential were monitored. Compared with the control, the results of solubility, the emulsifying activity index (EAI) and the emulsifying stability index (ESI) increased significantly (p < 0.05) at 200 MPa. The content of free SH increased significantly (p < 0.05) at 100 MPa. FTIR spectrum and fluorescence analysis confirmed the changes in the secondary and tertiary structures. The experimental results indicated that the structural and functional properties of HHP-pretreated RBPH improved.

FOAMING PROPERTIES OF MODEL SYSTEMS BASED ON WHEY

Background. One of the opportunities to expand the range and increase the share of desserts with a foamstructure is the use of multifunctional semi-finished products, the basis for which can be used protein-carbohydrate raw milk, in particular based on whey. Technologies for more than 100 names of products and semi-finished products using whey, the most of which have a liquid or condensed structure, have been developed.Studies on the possibility of developing dry semi-finished products are isolated. The aim of the articleis to study the functional and technological properties, in particular the foaming ability and stability of the semi-finished foam for whipped dessert products, depending on the ratio of its main prescription components. Materials and methods. For the study the whey dairy dry whey (WDDW) according to DSTU 33958–2016, dry cranberry extract (CE) TM Health Linkwere used. The foaming properties of the samples, namely the foaming ability (FA) and the stability of the foam (SF) were determined by the Lurie method. Results. The obtained solutions of reduced WDDW with different protein content showed certain foaming properties. The maximum manifestation was determined by the protein content of 5.8–6.5 % and temperature 5 ºC. The maximum value of foaming ability (FA) and foam stability (FS) model systems acquire the content of CE 13–18 %, which corresponds to pH 4.9–4.4. It is proved that with increasing sugar content in the range of 5–15 % FA increases by 20–25 %, the stability of the foam is almost unchanged.So, it is envisaged to use guar gum in the amount of 1 % by weight of the main components as a stabilizer. The maximum value of the FA system acquires at the beating speed (180–240) · 60s¹. Conclusion. The maximum foaming properties are shown by the semi-finished product for whipped dairy desserts, which contains: reduced WDDW with a protein content of 5.8–6.5 %, the cranberry extract 13–18 %, sugar 5–15 %. Technological parameters, according to which the maximum manifestation of foaming properties is observed, are the temperature of 5ºСand the beating speed (180–240) · 60 s¹.

FUNCTIONAL PROPERTIES OF CATFISH SKIN COLLAGEN HYDROLYSATES

Collagen hydrolysates were obtained from catfish skin collagen hydrolysis using catfish collagenase, pepsin and trypsin individually and mixed for 15-300min. The degree of hydrolysis , antioxidant activity based on, DPPH radical-scavenging activity (RSA), and reducing power (RP) for all obtained hydro lysates were studied , then the collagenase hydrolysate was (CH) was selected to be evaluated for antibacterial activity , functional properties including solubility, emulsification and foaming properties besides the toxicity . The highest values for RSA (72.5%) has been noticed when DH reached (24.30%) after 30 min. of hydrolysis by collagenase (CH). The water and oil holding capacities for this hydro lysate was compared to that for ASC (acid soluble collagen and PSC (pepsin soluble collagen), the results showed that the values recorded by CH were significantly higher than ASC & PSC. The molecular weight of CH peptides ranged from 180 to 11 Da. as analyzed by SDS- PAGE. The toxicity assay result revealed that CH is safe for human consumption. There was no antibacterial function for CH toward E.coli and S. aureus. At concentration of 2mg/ml. This study suggests that catfish collagen hydro lysate could be a good natural alternative for synthetic antioxidants in food industries.