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Several methods are used to recover compounds from these residues. Among them, ultrasound extraction has gained prominence due to its cellular disruption power. This work aimed to verify the action of ultrasound in increasing the yield of protein hydrolysate extraction from Pacific white shrimp (Litopenaeus vannamei) by-products. Proximal composition, hydrolysis degree, total content of carotenoids, and antioxidant activity (DPPH, ABTS, and reducing power) of the obtained hydrolysate was determined. The study found that the use of ultrasound concentrated more carotenoids, containing high antioxidant activity, increased the degree of hydrolysis, and accelerated the hydrolytic reaction rate. [ABSTRACT FROM AUTHOR]

Abstract This research evaluated the effect of the simultaneous substitution of fish meal and fish oil at 0, 30, 50, 70 and 100% (termed SS0, SS30, SS50, SS70 and SS100, respectively) with both Spirulina (Arthrospira platensis) and linseed oil. The effect on growth, colour, fatty acid (FA) profile, and liver and muscle antioxidant response in mullets (Mugil liza) were evaluated. A full substitution was not possible due to a final body weight reduction (p < 0.05). The colorimetric analyses showed an improvement in fillet colouration (p < 0.05). Also, we found a saturation of carotenoids in muscle at 30% substitution. The content of highly unsaturated fatty acids - HUFA (DHA, EPA and ARA) in muscle diminished as the substitution level increased and, at the same time, the level of these FAs in the diet diminished. We found interesting evidence of elongation from 18:3n-3 to 20:3n-3 when substitution with linseed oil levels was above 50% but no desaturation to 20:4 or 20:5n-3 was found, which could insinuate a certain n-3 HUFA requirement under the experimental conditions. Moreover, we noted an increase in the antioxidant capacity up to the treatment SS70; the SS100 treatment showed a diminution in the antioxidant capacity. It is concluded that a partial inclusion of Spirulina and linseed oil (50%) is possible, and that this replacement can increase antioxidant responses, improve its growth performance and can modulate the mullets fillet quality without affecting negatively fillet fatty acid content. Graphical abstract Mugil liza juveniles were fed diets with different levels of simultaneous substitution (SS) of fish meal and fish oil with Spirulina and linseed oil. Unlabelled Image Highlights • Simultaneous substitution of fishmeal and fish oil with Spirulina and linseed oil was assessed using Mugil liza juveniles • Partial inclusion of Spirulina and linseed oil (50%) is possible without hampering Mugil liza survival and growth • Full simultaneous substitution is not feasible probably as a result of the lack of some essential amino acids • We have found evidence of fatty acid elongation in the muscle of mullets. [ABSTRACT FROM AUTHOR]

The current study aimed to evaluate the influence of lipoic acid (LA) supplementation (439.84 ± 6.71 mg LA/kg feed) on antioxidants responses throughout the time in intestine, liver and muscle of juvenile common carp Cyprinus carpio . Two experimental groups were fed during four weeks with a diet with or without LA. Glutathione-S-transferase (GST) activity, glutathione (GSH) content, antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS) were evaluated in these organs. Also, a technique to measure protein disulfide bonds and sulfhydryl groups was optimized for intestine samples. GST activity was significantly higher (p < 0.05) in intestine after two weeks of supplementation. GSH content was also significantly higher (p < 0.05) in intestine, liver and muscle of fish fed with LA after two and three weeks, respectively. Total capacity antioxidant against peroxyl radicals was significantly increased (p < 0.05) in the muscle of animals fed with LA after the fourth week. Concentration of disulfide bonds was higher in the intestine of fish fed with LA but this group also showed higher concentration of sulfhydryl groups (p < 0.05). It is concluded that supplementation with LA is a safe strategy to induce antioxidant responses and improves the antioxidant status in different organs of common carp. Two week of supplementation are required to induce antioxidant responses in intestine and liver and three week for muscle. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of dietary supplementation with different concentrations of chitosan from shrimp tailings on the antioxidant and immune systems of juvenile Litopenaeus vannamei cultivated in a biofloc system (BFT) and subjected to abrupt salinity reduction. The experiment was performed with juvenile shrimp fed diets supplemented with four levels of chitosan: C0 (0 g kg−1 diet – control), C1 (1 g kg−1 diet), C3 (3 g kg−1 diet), and C5 (5 g kg−1 diet). After 35 days, the shrimp were exposed to an acute reduction in salinity from 30 to 5 for 24 h, and the hemolymph, gills, and hepatopancreas were collected. No significant differences were found in the growth performance and survival among treatments. In the gills, acute salinity reduction increased the activity of catalase (CAT), although this effect was reversed by the 5 g kg−1 diet (C5). Furthermore, glutathione-S-transferase (GST) activity was maintained at the basal level in shrimp fed a 1 g kg−1 diet (C1) but reduced in those fed C3 and C5. We also identified a reduction in lipid peroxidation in shrimp fed the C3 and C5 diets. In the hepatopancreas, the GST activities and glutathione (GSH) levels were higher in shrimp supplemented with chitosan, which showed a protective effect. Saline stress and chitosan supplementation did not affect differential hemocyte counts. In conclusion, the results of this study suggest that dietary intake of chitosan could enhance some antioxidant defenses of L. vannamei farmed in a BFT system. Thus, the inclusion of at least 1 g kg−1 chitosan could represent a good alternative to improve defense mechanisms and stress resistance, and it could also contribute to the development of sustainable aquaculture. • Salinity stress induced oxidative stress in shrimp cultivated in the BFT system. • Chitosan supplementation improved different antioxidant responses in both the gills and hepatopancreas of L. vannamei. • Chitosan reduced lipid peroxidation in the gills of shrimp subjected to salinity stress. [ABSTRACT FROM AUTHOR]