Development of emulsion gelatin gels for food application: Physicochemical, rheological, structural and thermal characterization.

The current work aimed to prepare emulsion gels based on European eel skin gelatin (ESG). The results revealed that the ESG exhibited interesting antioxidant and functional properties in a dose-dependent manner. The ESG has a gel strength of 354.86 g and high gelling and melting temperatures of about 33 and 43 °C, respectively. Hence, based on its interesting gelling ability, the ESG-based gel was employed to stabilize European eel oil (EO) emulsions. In this context, two emulsions were prepared by homogenization or homogenization followed by sonication at EO:ESG weight ratios of 1:2 and 1:4. The physicochemical, textural, structural and thermal properties of emulsion gelatin-based gels (EGGs) were evaluated. The EGGs had a rigid and a cohesive gel network, according to the textural and microstructural analysis. Structural and thermogravimetric analyses showed the effective entrapment of EO in the ESG gel network.

Development of delivery system based on marine chitosan: Encapsulationand release kinetic study of antioxidant peptides from chitosan microparticle.

The present work aims to encapsulate goby fish protein hydrolysate (GPH), endowed with antioxidant activity, through ionic gelation process using blue crab chitosan (CH) and tripolyphosphate anions and to evaluate the structural, thermal and antioxidant properties of the elaborated microparticles (MPs). The GPH-loaded MPs present spherical shape as seen by scanning electron microscopy (SEM) images and positive zeta potential. The increase of loaded GPH concentration led to the increase of encapsulation efficiency (EE) and to the reduction of the particle size. In fact, MPs, loaded with 2 and 5 mg/ml GPH, had EE values of 44 and 58% and mean particles size of 4.81 and 3.78 µm, respectively. Furthermore, thermogravimetric analysis (TGA) profiles revealed the enhanced thermal stability of encapsulated biopeptides compared to the free ones. Release kinetic data showed a Fickian diffusion behavior which follows swelling and a diffusion-controlled mechanism for peptides liberation. Finally, as opposed to unloaded MPs, an improvement of the antioxidant activity of the loaded MPs with biopeptides was observed.

Improved antioxidant activity and oxidative stability of spray dried European eel (Anguilla anguilla) oil microcapsules: Effect of emulsification process and eel protein isolate concentration.

The objective of this study was to prepare European eel oil (EO) microcapsules using European eel protein isolate (EPI) as a wall material and investigate its oxidative stability. The EPI emulsions were obtained at different EO: EPI ratios (1:1, 1:2 and 1:4, w/w) and using two emulsification procedures: Homogenization (H) and homogenization followed by ultrasonication (HU) treatments. The microcapsules prepared by combining the two emulsification processes (HU) and at core and wall ratio of was 1:4 presented the smallest particles size and the greatest encapsulation efficiency (68.50%) and oxidative stability. Scanning electron microscopy (SEM) images proved the spherical shape of all microcapsules without fissure on the surface. The capsules exhibited an interesting antioxidant activity depending on the EO:EPI ratio, especially for the metal chelating potential. Thus, the effect of ultrasonication process and the EPI concentration on the characteristic, the stability and the antioxidant activity of the encapsulated EO has been proved.

Preventive effect of goby fish protein hydrolysates on hyperlipidemia and cardiovascular disease in Wistar rats fed a high-fat/fructose diet.

This study was carried out to investigate the hypolipidemic, cardioprotective and anticoagulant properties of fish goby protein hydrolysates (GPHs) in rats fed a high fat and fructose diet (HFFD). Wistar rats were fed with HFFD for 2 months, coupled with the oral administration of GPHs and undigested goby protein (UGP). Compared with the standard diet, HFFD induced dyslipidemia and liver structure alterations, and increased pancreatic lipase activity. In addition, HFFD caused a significant increase in body weight. Interestingly, administration of UGP and GPHs to HFFD fed rats was efficacious in lowering serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-c) as well as hepatic TC and TG, and increased the serum high density lipoprotein cholesterol (HDL-c) content. Moreover, all treatments significantly decreased the atherogenic index and coagulant factor levels (thrombin and prothrombin). UGP and GPH administration also significantly decreased pancreatic lipase activity, which mitigates lipid accumulation. Similarly, UGP and its hydrolysates showed cardioprotective potential revealed by decreasing the risk of atherogenic and coronary artery disease and improving the liver architecture. The ex vivo plasma clotting test showed that GPHs exert a great therapeutic anticoagulant potential. The overall results demonstrated that GPH supplementation can counteract high-fat/fructose diet-induced obesity.

Ameliorating effects of goby fish protein hydrolysates on high-fat-high-fructose diet-induced hyperglycemia, oxidative stress and deterioration of kidney function in rats.

This study investigated the therapeutic potential of undigested goby fish (Zosterisessor ophiocephalus) muscle proteins (UGP) and their hydrolysates on high-fat-high-fructose diet (HFFD)-fed rats. HFFD induced hyperglycemia, manifested by a significant increase in the levels of glucose and glycogen as well as α-amylase activity when compared to normal rats. The administration of GPHs to HFFD-fed rats significantly decreased α-amylase activity and the contents of blood glucose and hepatic glycogen. By contrast, the UGP increased the glucose metabolic disorders in HFFD-fed rats. Furthermore, HFFD-fed rats showed oxidative stress, as evidenced by decreased antioxidant enzyme activities and glutathione (GSH) levels and increased concentration of the lipid peroxidation product malondialdehyde in liver and kidney. Interestingly, the daily gavage of UGP and GPHs improved the redox status in liver and kidney of HFFD-rats by ameliorating or reversing the above-mentioned changes. Moreover, GPHs exhibited a renal protective role by reversing the HFFD-induced decease of uric acid and increase of creatinine levels in serum and preventing some HFFD-induced changes in kidney architecture. The results demonstrate that GPHs contain bioactive peptides that possess significant hypoglycemic and antioxidant properties, and ameliorate renal damage in rats fed hypercaloric diet.

The influence of the extent of enzymatic hydrolysis on antioxidative properties and ACE-inhibitory activities of protein hydrolysates from goby (Zosterisessor ophiocephalus) muscle.

Antioxidant properties and angiotensin-converting enzyme (ACE) inhibitory activities of protein hydrolysates from goby (Zosterisessor ophiocephalus) muscle, with different degrees of hydrolysis (DH) from 5 to 25%, prepared by treatment with crude proteases extract from smooth hound intestines, were investigated. Goby protein hydrolysates (GPHs) are rich in Gly and Thr, which accounted for 14.1-15% and 11.6-13.2% of the total amino acids, respectively. The antioxidant activities of GPHs were investigated by using several in vitro assay systems. All GPHs exhibited significant metal chelating activity and DPPH free radical-scavenging activity, and inhibited linoleic acid peroxidation. For the ACE-inhibitory activity, as the DH increased, the activity of GPHs increased. The obtained results revealed that antioxidant and ACE-inhibitory activities of GPHs were influenced by the degree of hydrolysis. A medium degree of enzymatic hydrolysis was appropriate to obtain GPHs with good antioxidant activity, while small peptides were essential to obtain high ACE inhibitory activity.

Physical immobilization of Rhizopus oryzae lipase onto cellulose substrate: activity and stability studies.

Rhizopus oryzae lipase (ROL) was immobilized by adsorption onto oxidized cellulose fibers and regenerated films. The maximum adsorption level increases with the raise in the amount of carboxylic groups on cellulose surface confirming that adsorption is being governed mainly by electrostatic interaction between the enzyme and the substrate. This hypothesis was further confirmed by zeta-potential measurements showing a decrease in the zeta-potential of the fibers after enzyme adsorption. XPS analysis showed an intensification of the N 1s peak attesting the presence of the enzyme on the surface. The effect of temperature, pH and solvent polarity on the immobilized enzyme activity and stability was investigated. The catalytic esterification of oleic acid with n-butanol has been carried on using hexane as an organic solvent. A high conversion yield was obtained (about 80%) at 37 degrees C with a molar ratio of oleic acid to butanol 1:1 and 150IU immobilized lipase. The adsorption achieved two successive cycles with the same efficiency, and started to lose its activity during the third cycle.

Biooxidation of n-hexanol by alcohol oxidase and catalase in biphasic and micellar systems without solvent.

Alcohol oxidase from Pichia pastoris together with catalase from bovine liver was used to oxidize n-hexanol to hexanal. For this purpose, an aqueous buffer solution was mixed with large amounts of hexanol by simple agitation, yielding a biphasic system, or by adding the nonionic surfactant Brij 35. Initial velocities and reaction yields after 24 h were measured as a function of various parameters such as the amounts of enzymes, hexanol, or surfactant. High enzymatic activity was determined for hexanol concentrations of between 20 mass% and 80 mass% without using any additional organic solvent. The homogenization of the biphasic systems with the help of Brij 35 did not yield a significant improvement of the bioconversion, which would justify the use of surfactants.