Collagen from jumbo squid fin: extracting conditions and influence of the protease system on collagen hydrolysate antioxidant activity Colágeno de aletas de calamar gigante: condiciones de extracción y efecto del sistema proteolítico en la actividad antioxidante de sus hidrolizados The optimal alkaline and acid conditions for insoluble collagen extraction from jumbo squid fin (JSF) were established by factorial analysis. Dependent variable: protein concentration; independent variables: NaOH and HCl concentrations. The antioxidant properties of JSF collagen hydrolysates obtained by two protease systems were studied. Moreover, jumbo squid skin (JSS) collagen was obtained and hydrolysated under optimal conditions. The optimal extraction condition was 0.5 M NaOH followed by 0.2 M HCl. Collagen α-chains were detected in both JSF and JSS. Collagen β-component was detected only in JSS. JSS collagen showed higher levels of polar and hydrophobic amino acids. The JSF hydrolysates produced by subtilisin showed a lower degree of hydrolysis and higher antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), and oxygen radical absorbance capacity-fluorescein (ORAC FL )) than those produced by a mixture of trypsin, chymotrypsin, and peptidase. The JSS hydrolysates showed a higher antioxidant capacity. We have thus established a suitable process to improve the utility of JSF.Keywords: fin collagen; extraction conditions; protease system; hydrolysate; antioxidant activity La mejores condiciones para la extracción del colágeno insoluble de las aletas del calmar gigante (JSF) fueron establecidas aplicando un diseño factorial. Variable dependiente: concentración de proteína; variables independientes: concentraciones de NaOH y HCl. Se comparó la actividad antioxidante de hidrolizados del colágeno de JSF, obtenidos mediante dos sistemas proteolíticos. Además, usando las mejores condiciones se extrajo el colágeno de la piel del calamar (JSS) e hidrolizó. Las mejores condiciones de extracción fueron: NaOH 0.5 M y HCl 0.2 M. Las bandas α se observaron en ambos colágenos. El β-componente de colágeno solo se detectó en JSS. JSS mostró mayor contenido de aminoácidos polares e hidrofóbicos. Los hidrolizados de JSF producidos por subtisilina presentaron menor grado de hidrólisis, la más alta actividad antioxidante (DPPH, TEAC, ORAC FL ) que los obtenidos por una mezcla de tripsina, quimotripsina y peptidasas. Los hidrolizados del JSS mostrarón la mayor actividad antioxidante. Se estableció un proceso para un mejor aprovechamiento de JSF.

Ultrasonic pulses are considered green technology for the improvement of the functional properties of proteins. In this study, four high-intensity ultrasound pulse treatments (ultrasound-pulsed gelatin (UPG)-42, UPG-52, UPG-71, UPG-84, and non-pulsed control gelatin (CG)) were applied to tilapia (Oreochromis niloticus) skin gelatin in order to study their effect on its physicochemical and antioxidant properties; a non-treated gelatin was used as a control. UPGs showed a significant increase in soluble protein and surface hydrophobicity compared to the control gelatin, and no significant difference was found in the electrophoretic profiles. The effects on the secondary structure were studied by circular dichroism and infrared spectra, and these showed that the random coil conformation was the main component in all treatments and the ultrasonic treatments only affected the α-helix and β-sheet proportion. Finally, the ABTS ((2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric reducing ability) assays demonstrated that ultrasound treatments could improve the antioxidant activity of gelatins as free radical scavengers and electron donors. These results suggest that high-intensity ultrasound pulse technology is useful to improve fish gelatin antioxidant properties, which could be associated with secondary structure disruption.

Chitosan (85% deacetylated, viscosity > 400 MPa, and molecular weight of 570.3 kDa)/squid gelatin hydrolysates (SGH) were prepared by incorporating SGHs (10%, 20%, and 40%) into chitosan films. SGH were obtained from squid skin gelatin by hydrolysis with Alcalase. The effects of adding SGH on the physical, chemical structure, mechanical, degradability, antioxidant, and antifungal properties of the chitosan films were evaluated. Films containing SGH were opaquer and more colored than the reference. Scanning electron microscope imaging showed that the surface sections of the CH/SGH films were smooth and homogeneous, though a small amount of insoluble microparticles was observed. Atomic force microscopy indicated that the surface roughness of the chitosan films increased with the addition of SGH. Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy suggested an excellent compatibility of the components due to hydrogen bonding. The flexibility and in vitro degradability of the films increased as the SGH content increased. The 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate acid and 1,1-diphenyl-2-picrylhydrazyl scavenging rate of films increased with the addition of SGH. Moreover, films containing 20% SGH improved the fungistatic activity against Aspergillus parasiticus of chitosan films. The chitosan/SGH composite films have the potential for use in food packaging.

This study investigated the performance of chitosan based films with added, high‐intensity ultrasound‐pulsed, gelatins (42, 52, 71 and 84 W cm−2). The mechanical, structural, chemical and antioxidant properties were investigated, to evaluate the potential of ultrasound as a technique to improve film properties. The tensile strength and elastic modulus of films containing ultrasound‐pulsed gelatins showed a significant increase, while the elongation parameter showed a significant decrease. Micrographs showed that all films presented agglomerations. The infrared spectra of the films displayed characteristic shifts in the chitosan and gelatin spectra, which may be the result of hydrogen bridge interactions and electrostatic interactions between the two polymers. The antioxidant capacity was analyzed through the ferric reducing antioxidant power (FRAP) assay and the 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS) assay of films and showed that gelatins treated with higher acoustic intensity had improved antioxidant capacity. High‐intensity ultrasound‐treated gelatin enhanced the strength, elasticity and antioxidant properties of the chitosan based films. © 2020 Society of Chemical Industry

Large volumes of waste are generated in the processing operations of the fishing industry. These effluents contain potentially useful proteins. However, it is necessary to concentrate them for utilization. The stickwater (SW) resulting from this operation was subjected to a protein-fractionation step, pH adjustment (acid + alkaline) and ultrasonic pulsing in order to aid in hydrolysis and evaluate its functional and nutritional properties. The protein fractions, as well as the protein hydrolysates present in the tail water, had a chemical composition of 54.85 ± 4.21 and 74.81 ± 3.89 protein (%), 0.8 ± 0.1 and 0.2 ± 0.015 fat (%), 7.21 ± 0.67% ash (%), respectively. The increase in low-molecular-weight peptides results in an increase in free-radical scavenging activity. However, the increase in ferric-reducing antioxidant power may be due to the HCl treatment performed by the company. An increase in the functional properties of the samples treated with ultrasonic pulses was observed. Therefore, the chemical, nutritional and functional characteristics of stickwater suggest its potential use as a food additive.

Las aguas residuales que provienen de las industrias del enlatado o de las reductoras de pescados, son una fuente rica en una gran variedad de compuestos químicos de interés industrial y de otros altamente perjudiciales para el medio ambiente. Con el fin de reducir el impacto negativo de estos efluentes en los ecosistemas marinos, se han desarrollado diversas técnicas para establecer procedimientos de remoción de los sólidos y recuperación de los nutrientes, como las proteínas para aplicaciones en la industria alimentaria, agroquímica y farmacéutica. Estas proteínas son concentradas mediante una variedad de métodos, siendo el más utilizado la ultrafiltración. Sin embargo, son varias las técnicas de recuperación y modificación de los productos pesqueros que mejoran las cualidades nutricionales, funcionales y biológicas de los concentrados de proteínas en las aguas residuales. En esta revisión, se examinan y se discuten las técnicas no sólo para el tratamiento de los sólidos de las aguas residuales de la industria del enlatado y de la reductora de pescado, sino también de los compuestos químicos presentes y de otros fluidos resultado del procesamiento de los productos de la pesca, con especial mención del uso de la ultrafiltración para la obtención de las proteínas destinadas a las industrias citadas al inicio.

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ABSTRACT. Physical and chemical characteristics of lyophilized biofloc produced into the culture of whiteleg shrimp was determinated. The study consisted in the evaluation of biofloc produced with four experimental diets, isoproteic (35%) and isolipidic (8%), with different fishmeal content: 0 g kg -1 (T0), 100 g kg -1 (T1), 200 g kg -1 (T2), 300 g kg -1 (T3), and a commercial diet with 300 g kg -1 (TC) as a control. The shrimp was cultured in low salinity (5 g L -1) at a density of 600 ind m -3. The bioflocs were manually collected at day 28, lyophilized, and processed. Proximal composition was determined. To analyze morphology and particle size, photomicrographs were obtained using a Scanning Electron Microscope (SEM). Molecular weights of the protein hydrolysates were determined, and finally the bioflocs protein surface hydrophobicity (S0) was measured. No significant differences were detected for protein (360-404 g kg ) were different. The hydrolysate protein molecular weights were similar, in all cases varied from 22 to 200 kDa. The 50% of lyophilized particles had sizes from 3 to 15 μm. The fluorescence spectra slopes indicated differences in protein surface hydrophobicity (S0) between the treatments. In general, the physical and chemical characteristics of the bioflocs were independent of the used diet. The lyophilized biofloc has properties that allow its use as a protein source or raw material for biotechnological processes.