Gel Strength Properties Research Articles

Cryoprotective role of konjac oligosaccharide on silver carp proteins during frozen storage through molecular dynamic simulation

The cryoprotective effect of konjac oligosaccharide (KOG) on the silver carp surimi proteins during frozen storage was analyzed. Meanwhile, molecular dynamic simulation (MD) was carried out to examine the insight interaction of KOG with myosin. The Ca2+-ATPase and gel strength decreased in all samples, despite the treatment with a sucrose (4%) + sorbitol (4%) mixture as PC and KOG (1 and 3%). The samples added with no cryoprotectants (C) showed a remarkable decline in Ca2+-ATPase activity and gel strength. The decline in these properties could be due to oxidative changes in myosin, ice crystallization, and protein denaturation. Most interestingly, KOG (3%) incorporated samples that presented significant constancy in Ca2+-ATPase and gel strength properties, this stability was further proved with a MD computational study. Our findings of homology and MD analysis affirmed that KOG could substitute water molecules and form hydrogen bonds with amino acid residues, thereby leading to protein stability. Overall, the KOG water substitution action played an efficient cryoprotective effect on frozen silver carp protein. Furthermore, this application could extend the role of KOG at the industrial level as an effective cryoprotectant.

Gelatins and antioxidant peptides from Skipjack tuna (Katsuwonus pelamis) skins: Purification, characterization, and cytoprotection on ultraviolet-A injured human skin fibroblasts

For full use of Skipjack tuna (Katsuwonus pelamis) canning by-products, gelatins (STG) were extracted from tuna skins using acid (STG-A), enzyme (STG-E) and hot water (STG-H) methods with yields of 65.30 ± 1.56%, 39.83 ± 1.61%, and 50.97 ± 1.44%, respectively. Due to the high imino acid contents (228, 216, and 213 residues/1000 residues for STG-A, STG-E, and STG-H, respectively), STG-A showed the highest transparency and gel strength properties. Amino acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet (UV) and Fourier transform infrared spectroscopy (FTIR) analysis confirmed that STG-A, STG-E, and STG-H kept the main structure of type I collagen, but enzyme and hot water extraction methods showed much stronger hydrolysis ability on α and β chains. Moreover, neutrase hydrolysate (STG-AH) of STG-A showed the highest 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging activity and the fraction STG-AH-І (<3.5 kDa) from STG-AH prepared by ultrafiltration could significantly protect human skin fibroblasts (HSFBs) against ultraviolet-A (UVA) injury. Furthermore, nineteen peptides with high antioxidant activity were purified from STG-AH-І and identified. These results suggested that STG-AH and its derived antioxidant peptides could serve as potential ingredients applied in health benefiting products for preventing UVA injury.

A polyacrylamide hydrogel for application at high temperature and salinity tolerance in temporary well plugging

In addition to conventional approach to ensure the successful application of polymer hydrogels in maintaining temporary well plugging, exact analysis of gel formation and gel strength properties in wellbore are necessary. In this work, bottles and rheology tests are used to investigate the polymer hydrogel gelation time and cross-linking kinetics of sol–gel systems which consist of polyacrylamide and chromium acetate hydroxide as a cross-linker. The effects of temperature of 90 °C and pressure of 3000 psi (typical Iranian oil well condition) were studied in relation to gelation time, strength and the mechanical properties of the hydrogel. The average molecular weight of the polymer chains between cross-link ties was evaluated using an oil-well laboratory system and compressive strength test. Differential scanning calorimeter (DSC) analysis of dried gel and the effect of temperature on the kinetics of the gel swelling in different solutions such as distilled water, tap water, formation water and oil were studied. The results showed that the number of tie points between each entanglement has not much reduced under pressure. Therefore, the prepared hydrogel can maintain its chemical structure under the Iranian oil well pressure and can be proposed to field studies. The degree of sol–gel reaction of prepared hydrogel and the activation energy based on the Arrhenius equation were calculated to be 1.5 and 274 kJ/mol, respectively.

Comparison of the Acidic and Alkaline Treatment on Emulsion Composite Gel Properties of the Proteins Recovered from Chicken Breast by Isoelectric Solubilization/Precipitation Process

The functional properties of gels and emulsion composite gels made from chicken breast protein recovered at different pH strategies (at pH 3.5 called C3.5, at pH 11 called C11 and chicken breast mince as the control called CON) were compared. Alkali-extracted proteins performed significantly better (P < 0.05) in gel strength properties, compared with acid-extracted proteins. However, the acid-processed protein showed superior flavor qualities (P < 0.05) and similar (P > 0.05) water retention capacity. The isoelectric solubilization and precipitation (ISP)-extracted protein with fat addition presented more favorable qualities in terms of better flavor and smoother taste, whereas the addition of fat significantly reduced strength of alkaline-aided protein gels. Meanwhile, the alkaline-aided exhibited appreciable emulsion stability level (P < 0.05) rather than acid-aided. The results presented that protein obtained from ISP method is more suitable to be applied for developing emulsion-type products. Alkaline-aided protein showed better qualities than acid-aided protein. Practical Applications Isoelectric solubilization and precipitation (ISP) processing has been attempted for improving protein gelation properties. However, little is known about the emulsion properties of the ISP-extracted protein. Furthermore, the function properties of the emulsion composite gel made by the protein were not fully investigated yet. This study investigates the function properties of protein from chicken breast extracted by ISP methods. According to the obtained data, the ISP method was suitable for applying to manufacture emulsion-type product. Enhancing the product function properties is important to the meat industry.

PREPARATION, ULTRASTRUCTURE, AND FUNCTIONAL PROPERTIES OF EGG ALBUMIN AND CORN ZEIN MODIFIED VIA THE PLASTEIN REACTION

Scanning Electron Microscopy (SEM) was used to study changes during the preparation of plasteins from egg albumin and corn zein protein isolates. This included an examination of protein particles that had been spray-dried, freeze-dried, hydrolyzed, and synthesized into plastein reaction products. Water holding capacity, oil binding capacity, and gel strength properties before and after modification are discussed. The study demonstrated that the quantity and quality of plastein products are dependent upon both the substrate and the enzyme used. A possible relationship is proposed between ultrastructural characteristics and actual functional performance of unmodified and modified proteins.