Shell water-soluble matrix protein from oyster shells promoted proliferation, differentiation and mineralization of osteoblasts in vitro and vivo.

Matrix protein is secreted by the membrane of bivalve shellfish to and used to regulate shell biomineralization. In this study, we extracted water-soluble matrix protein (WSMP) from oyster shells to investigate its effects on osteogenic differentiation and mineralization of MC3T3-E1 cells and osteoporosis rats. Our results suggested that WSMP was an acidic glycoprotein by amino acid analysis and secondary structure analysis. In vitro, WSMP could promote osteoblastic proliferation. Moreover, alkaline phosphatase (ALP) and osteocalcin (OCN) were increased, mineralized nodules were increased, and BMP-2 expression was up-regulated. Additionally, in vivo, tartrate-resistant acid phosphatase (TRAP) and Bone alkaline phosphatase (BALP) expressions in the medium-dose and high-dose groups were significantly decreased compared with the model group, while OCN expression was significantly increased. Bone mineral density (BMD) and bone mineral content (BMC) of bone recovered significantly. In summary, WSMP can promote the proliferation, differentiation and mineralization of osteoblasts in vitro and in vivo.

A novel blue crab chitosan/protein composite hydrogel enriched with carotenoids endowed with distinguished wound healing capability: In vitro characterization and in vivo assessment.

This work aimed to the development of chitosan and protein isolate composite hydrogels, for carotenoids-controlled delivery and wound healing. By increasing the concentration of the protein isolate, chitosan hydrogels were more elastic at a protein isolate concentration not exceeding 15% (w/w). Chitosan-protein isolate composite hydrogels revealed low cytotoxicity towards MG-63 osteosarcoma cells. Thanks to its appropriate structural, swelling and mechanical resistance properties, chitosan hydrogel (3%; w/v), reinforced with 15% (w/w) of protein isolate, was selected for the carotenoids in vitro release study. Release profiles, show delivery patterns, where carotenoids were more barely released at a pH 7.4 medium (p < .05), compared to more acidic microenvironments (pH 4.0 and pH 2.0). Thus, developed hydrogels could be applied as pH-sensitive intelligent carriers, for drugs-controlled release, with interesting antioxidant abilities. The in vivo healing potential of hydrogels in rats' models was further studied. Topical application of hydrogel-based patches allowed the acceleration of wound healing and the complete healing, for composite hydrogel enriched with carotenoids.

Partially degraded chitosan-based flocculation to achieve effective deodorization of oyster (Crassostrea gigas) hydrolysates.

Aquatic protein hydrolysates are usually associated with unpleasant odors and high fat content, which seriously restricts their industrial utilization. In this study, chitosans with different molecular weights produced by hydrogen peroxide degradation were applied to establish a flocculation method, using for the deodorization and defatting of oyster (Crassostrea gigas) hydrolysates. GC-MS analysis showed that the method markedly decreased the content of the fishy odor constituents. Up to 92 % fat and part of the heavy metals were effectively removed. Protein recovery percentage and solid recovery percentage were 83.43 ± 0.35 % and 76.36 ± 0.52 %, respectively, at the optimum dose (150 mg/L) of chitosan (83 % of deacetylation degree, 77 kDa). Thus, chitosan flocculation-coupled centrifugation (5000g, 1 min) can effectively solve the current drawbacks of engineering disc centrifuges and can be industrially used for defatting and deodorization during aquatic food processing.

Insight into the allergenicity of shrimp tropomyosin glycated by functional oligosaccharides containing advanced glycation end products.

Tropomyosin (TM) is the main allergen of shrimp. Glycation reportedly reduced the allergenicity of TM, and the allergenicity reduction was heavily dependent upon the sources of saccharides. In this work we investigated, how glycation of tropomyosin by functional oligosaccharides affected the allergenicity. Compared to TM, the TM glycated by galacto-oligosaccharide (TM-GOS), mannan-oligosaccharide (TM-MOS) and maltopentaose (TM-MPS) had lower allergenicity and induced weaker mouse allergy responses. While the TM glycated by fructo-oligosaccharide (TM-FOS) had stronger allergenicity and induced severe mouse allergy symptoms, due to the generation of neoallergns that belonged to advanced glycation end products (e.g. CML). Therefore, GOS, MOS and MPS could be applied to desensitize shrimp TM-induced food allergy through glycation, while FOS was not suitable to reduce TM allergenicity. Glycation of TM by GOS, MOS and MPS, especially for MPS, significantly reduced allergenicity and alleviated allergy symptoms, which could be potentially explored for immunotherapy for shrimp-allergic patients.

Evaluation of physicochemical and functional properties of spray-dried protein hydrolysate from non-penaeid shrimp (Acetes indicus).

BACKGROUND: Protein hydrolysate powder was prepared from non-penaeid shrimp (Acetes indicus) by enzymatic hydrolysis using Alcalase enzyme. Extraction conditions such as pH (6.5, 7.5 and 8.5), enzyme to substrate ratio (1.0, 1.5 and 2.0) and temperature (40, 50 and 60 °C) were optimized against the degree of hydrolysis using response surface methodology. RESULTS: Protein hydrolysate comprised of 740 g kg-1 protein, 150 g kg-1 ash and 90 g kg-1 fat contents. The amino acid score showed superior attributes with 56% essential amino acids. Furthermore, the functional properties of spray-dried protein hydrolysates were evaluated. Protein solubility was found to be the 90.20% at pH 2 and 96.92% at pH 12. Emulsifying properties were found to vary with the concentration of protein hydrolysates and the highest emulsifying capacity (26.67%) and emulsion stability (23.33%) were found at a concentration of 20 mg mL-1 . The highest and the lowest foaming capacity were observed at pH 6 and pH 10 with a concentration of 20 mg mL-1 . The water holding capacity of protein hydrolysate was found to increase with concentration, with a value of 5.4 mL g-1 at a concentration of 20 mg mL-1 . CONCLUSION: The results of the present study indicate that the use of A. indicus for the production of protein hydrolysate has good functional properties and nutritional value, rendering it suitable for broad industrial food applications. © 2019 Society of Chemical Industry.

Physicochemical changes of myofibrillar proteins of squid (Argentinus ilex) induced by hydroxyl radical generating system.

The effect of a hydroxyl radical generating system (HRGS), which contained FeCl3, sodium ascorbate, and different concentrations of H2O2, on the physiochemical properties of myofibrillar protein (MP) from squid mantles, has been investigated. The effect of different exposure times to HRGS was also considered. Compared to non-oxidized MP, a significant (p < 0.05) increase in carbonyl content (more than 50% of its original content) and protein solubility, as well as in surface hydrophobicity, was observed in the oxidative MP. With different treatment times, a sharp decrease (p < 0.05) in sulfhydryl content was detected. In addition, hydroxyl radical treatment significantly reduced the MP gel's texture properties, whiteness and water holding capacity, especially at higher concentrations of H2O2. This observation could be attributed to extensive disorderly and less compact structure of MP gels. The results demonstrate the negative effect of HRGS on the structural and functional properties of MP from squid mantles.

High-Pressure Homogenization Pre-Treatment Improved Functional Properties of Oyster Protein Isolate Hydrolysates.

The effects of HPH (high-pressure homogenization) pre-treatment on the functional properties of OPIH (oyster protein isolates hydrolysates) were studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles, solubility, particle size distribution, zeta potential, surface hydrophobicity, emulsifying activity index and microstructure of emulsions were analyzed. Results indicated that HPH pre-treatment increased the accessibility of OPI to trypsin hydrolysis, resulting in decease in particle size, increase in solubility, absolute zeta potential, surface hydrophobicity and emulsifying activity index. In addition, HPH pre-treated OPIH emulsions became more uniform and the particle size of droplets decreased. These results revealed that HPH pre-treatment has the potential to modify the functional properties of OPIH.