Lipid Oxidation in Fish and Fish Products of Interest for European Aquaculture

187 pages[EN] This thesis is based on three main trials. The overall aim of the present PhD thesis was to investigate the effect of some infra vitam and post mortem factors on oxidative stability of fish muscle. Killing procedures, such as percussion, asphyxia in air, and asphyxia by carbon monoxide (CO) were tested. Moreover, the effect of the utilization of mechanical separation technique (MSM) on oxidative stability of fish muscle was also investigated.[IT] Questa tesi si basa su tre studi principali. L'obiettivo generale della presente tesi di dottorato è stato quello di studiare l'effetto di alcuni fattori infra vitam e post mortem sulla stabilità ossidativa del muscolo di pesce. Le procedure d’uccisione, come la percussione, l'asfissia in aria e l'asfissia da monossido di carbonio (CO) sono state testate su specie di grande importanza economica, come il salmone atlantico e la trota iridea. Inoltre è stato studiato l'effetto dell'impiego della tecnica di separazione meccanica delle carni (CSM) impiegata su specie di pesci di interesse per l’acquacoltura europea.N

From farm to fork: lipid oxidation in fish products. A review

Lipid oxidation is a very complex and important event threatening the quality of foods especially of those containing highly unsaturated fats. Fish are the main source of polyunsaturated fatty acids that, unfortunately, are highly susceptible to degradation process, such as oxidation. Fish supply chain generally involves many steps and each of them together with their interaction might play a central role in muscle quality maintenance. From this review emerged that antioxidants supplementation diet can play a central role to limit the detrimental effects of stress (pre-slaughter or at killing) and storage. In this sense, lycopene shows the best antioxidant activity during stressful conditions while α-tocopherol acts preferentially in long-term frozen storage. Stress just before or at slaughter can greatly threaten flesh quality both immediately and after storage by inducing numerous metabolic pathways, that often involve the production of very reactive molecular species, such as hydroperoxides. A common operation such as bleeding can significantly reduce both reactive molecules and haemoglobin (Hb), which is recognised as a great pro-oxidant. Temperature and duration are two critical points of storage phase which has to be considered even by consumers. Frozen storage at very low temperatures (−30 °C, −40 °C) confirms to be the best storage practise. Finally, cooking can compromise aromatic profile of cooking fillets. Thus, feeding antioxidant, reducing stress both during pre-slaughter practise and at killing, good storage practises, if associated with an appropriate cooking method (low temperature, short time) seems to be the clues for preserving the fragile lipid fraction from farm to fork

A commercial macroalgae extract in a plant-protein rich diet diminished saturated fatty acids of Oncorhynchus mykiss Walbaum fillets

Seaweeds are considered novel feed ingredients, nutraceutical compounds and source of pigments and proteins. They appear to possess bioactive properties, such as hypolipidemic, antioxidant and immune-stimulative actions; furthermore, their proteins are considered just as nutritious as terrestrial vegetables. In the present work, rainbow trout (Oncorhynchus mykiss Walbaum) was fed for 95 days with three diets: a fishmeal-based positive control diet (C+), a vegetable protein-based negative control diet (C−) and a diet similar to C − where 5% of soybean concentrate was replaced by a commercial blend of seaweeds (T). The monitored parameters were fish performance, physical and marketable characteristics, fillet oxidative status and fatty acid content. The estimated indices of enzyme activities involved in lipid metabolism were calculated. Fish performances were reduced in C − and T fish; C − and T fillet fatty acid (FA) profiles globally showed the same pattern and were distinct from C+, i.e. with a lower content of polyunsaturated FAs and a higher content of monounsaturated and polyunsaturated n6 FAs; contrarywise, saturated FAs were significantly lower in T group in comparison to the other two groups (p <.01). The estimated indices of enzyme activity highlighted differences between dietary groups; desaturase activities of C18 and n3 FAs were higher in T in comparison to C− (p <.001). A slight impoverishment of antioxidant activity was found in T compared to C + group. Dietary seaweeds seemed to be capable of influencing fillet FA composition as well as the activity of enzymes related to lipid metabolism. Further studies in this regard are encouraged.Highlights Seaweeds are novel feed ingredients with nutraceutical properties Saturated fatty acids of rainbow trout fillets were lowered by seaweed inclusion in the diet Estimated desaturase activities of C18 and n3 fatty acids were higher in seaweed-fed trout

Ginger (Zingiber officinale Roscoe) powder as dietary supplementation in rabbit: life performances, carcass characteristics and meat quality

The aim of this study was to evaluate the effect of dietary Zingiber officinale Roscoe (ginger) powder on rabbit productive performances, meat quality and shelf-life of raw and cooked meat. Ninety hybrid rabbits of 60 days old were fed three different diets: basal diet (control, C), basal diet supplemented by 4 g of ginger powder on 100 g of feed (G4) and basal diet supplemented by 8 g of ginger powder on 100 g of feed (G8) (3.6 and 7.2 g/100 g of dry matter for G4 and G8, respectively). Live weight, average daily gain and feed intake were recorded. Ten rabbits of each group were slaughtered at 90 days of age and meat quality was assessed during seven days of storage at 4 °C. Live performance and slaughter traits did not show any significant differences. Dietary ginger powder induced modification in pH of raw samples and in colour indexes of both raw and cooked meat. Lipid oxidation of raw samples was delayed in time by ginger feed addition even if no modification was highlighted in antioxidant capacity. Ginger powder could be a potential supplementation in diet of rabbits for increasing meat shelf-life

Design, synthesis, docking studies and monoamine oxidase inhibition of a small library of 1-acetyl- and 1-thiocarbamoyl-3,5-diphenyl-4,5-dihydro-(1h)-pyrazoles

New N-acetyl/N-thiocarbamoylpyrazoline derivatives were designed and synthesized in high yields to assess their inhibitory activity and selectivity against human monoamine oxidase A and B. The most important chiral compounds were separated into their single enantiomers and tested. The impact of the substituents at N1, C3 and C5 positions as well the influence of the configuration of the C5 on the biological activity were analyzed. Bulky aromatic groups at C5 were not tolerated. p-Prenyloxyaryl moiety at C3 oriented the selectivity toward the B isoform. The results were also corroborated by molecular modelling studies providing new suggestions for the synthesis of privileged structures to serve as lead compounds for the treatment of mood disorders and neurodegenerative diseases

Fatty acid profile of lipids and caeca volatile fatty acid production of broilers fed a full fat meal from Tenebrio molitor larvae

Volatile fatty acid production (VFA) in the caeca and fatty acid profile of meat and fat depotswere investigated on 62 days old broiler equally divided in 2 groups fed with a corn-soybean(SBM) or a corn-insect meal (TML, fromTenebrio molitorlarvae) based diet from 30 days of age.The total amount of VFAs was higher (p<.01) in broilers fed TML and the same happened forall the single VFA studied in the trial. When the VFAs were expressed as percentage of totalVFAs, acetate, propionate and valerianate were higher (p<.01) in SBM group, while the propor-tion of butyrate was higher (p<.01) in broilers fed TML. The fatty acids C12:0 and C14:0 hadhigher percentages (p<.01 andp<.05, respectively) in the intramuscular fat of broilers fed TMLdiet. Regarding the FA groups (SFA, MUFA and PUFAs), only the PUFAn1 fatty acids were higher(p<.01) in the broilers fed TML diet. Insect meals can affect the microbial activity in broilercaeca and, in addition, induced very few modifications in the fatty acid profile of broiler breast

Benzo[b]tiophen-3-ol derivatives as effective inhibitors of human monoamine oxidase: design, synthesis, and biological activity

A series of benzo[b]thiophen-3-ols were synthesised and investigated as potential human monoamine oxidase (hMAO) inhibitors in vitro as well as ex vivo in rat cortex synaptosomes by means of evaluation of 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio and lactate dehydrogenase (LDH) activity. Most of these compounds possessed high selectivity for the MAO-B isoform and a discrete antioxidant and chelating potential. Molecular docking studies of all the compounds underscored potential binding site interactions suitable for MAO inhibition activity, and suggested structural requirements to further improve the activity of this scaffold by chemical modification of the aryl substituents. Starting from this heterocyclic nucleus, novel lead compounds for the treatment of neurodegenerative disease could be developed

Effect of mechanical separation process on lipid oxidation in European aquacultured sea bass, gilthead sea bream, and rainbow trout products

Mechanical separation systems are a good option to create new fish products and open new market, however studies on the effect on quality of mechanical treatment on species of interest for European aquaculture, such as European sea bass, gilthead sea bream, and rainbow trout are scarce. Thus in this research, the effect on colour, nutritional quality, and lipid stability was considered immediately after separation process and after 90 days of frozen storage. Results revealed that mechanical separation technique significantly affected colour and lipid stability of the three studied species. Increases in L* and secondary oxidation products were observed, together with a decrease of antioxidant capacity. Nutritional value instead was unaffected by treatment. Thus, mechanical separation process could represent a new way to better exploit species of interest for European aquaculture and acquire new market niches, but oxidative processes during the treatment have to be limited and kept under control

Application of laboratory methods for understanding fish responses to black soldier fly (Hermetia illucens) based diets

A major challenge for development of sustainable aquafeeds is its dependence on fish meal and fish oil. Replacement with more sustainable, nutritious and safe ingredients is now a priority. Over the last years, among several alternatives proposed, insects have received great attention as possible candidates. In particular, the black soldier fly (Hermetia illucens; BSF) represents a concrete example of how the circular economy concept can be applied to fish culture, providing a valuable biomass rich in fat and protein valorising organic by-products. In the last decade, several studies have been published about the use of different BSF dietary inclusion levels for various fish species including experimental models. Varying and encouraging results have been obtained in this research field using a plethora of laboratory methodological approaches that can be applied and coupled to obtain a comprehensive view of the BSF-based diets effects on fish physiology, health, and quality. The present review aims to explore some of the most promising laboratory approaches like histology, infrared spectroscopy, gut microbiome sequencing, molecular biology, fish fillets’ physico-chemical and sensory properties, essential for a better understanding of fish welfare and fillet quality, when BSF is used as aquafeed ingredient. In particular, great importance has been given to European finfish species and experimental models.publishedVersio

Effects of stunning methods on pre rigor changes in rainbow trout (Oncorhynchus mykiss) reared at two different temperatures

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