Seasonal Variations in Proximate and Fatty Acid Composition of Viscera ofSardinella aurita, Sarpa salpa, andSepia officinalisfrom Tunisia

Marine Animal Co-Products-How Improving Their Use as Rich Sources of Health-Promoting Lipids Can Foster Sustainability

Marine lipids are recognized for their-health promoting features, mainly for being the primary sources of omega-3 fatty acids, and are therefore critical for human nutrition in an age when the global supply for these nutrients is experiencing an unprecedent pressure due to an ever-increasing demand. The seafood industry originates a considerable yield of co-products worldwide that, while already explored for other purposes, remain mostly undervalued as sustainable sources of healthy lipids, often being explored for low-value oil production. These co-products are especially appealing as lipid sources since, besides the well-known nutritional upside of marine animal fat, which is particularly rich in omega-3 polyunsaturated fatty acids, they also have interesting bioactive properties, which may garner them further interest, not only as food, but also for other high-end applications. Besides the added value that these co-products may represent as valuable lipid sources, there is also the obvious ecological upside of reducing seafood industry waste. In this sense, repurposing these bioresources will contribute to a more sustainable use of marine animal food, reducing the strain on already heavily depleted seafood stocks. Therefore, untapping the potential of marine animal co-products as valuable lipid sources aligns with both health and environmental goals by guaranteeing additional sources of healthy lipids and promoting more eco-conscious practices.

Low-Toxicity Solvents for the Extraction of Valuable Lipid Compounds from Octopus (Octopus vulgaris) Waste

This study focused on the recovery of valuable lipid compounds from octopus (Octopus vulgaris) by-products. Extraction conditions of total lipids (TLs), phospholipids (PLs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were optimized by employing a Simplex-Lattice design; for it, different relative concentrations of three low-toxicity solvents (ethanol, acetone, and ethyl acetate) were considered. The optimization process was also addressed in reference to fatty acid (FA) ratios (total polyunsaturated FAs/total saturated FAs and total ω3 FAs/total ω6 FAs). The variance analysis of multiple regression data demonstrated that the quadratic model was significant (p < 0.05) for TL, PL, and DHA values and the ω3/ω6 ratio. As a result, the following optimized values were obtained: 113.8 g·kg-1 dry by-products (TLs), 217.3 g·kg-1 lipids (PLs), 22.55 g·100 g-1 total FAs (DHA), and 3.70 (ω3/ω6 ratio). According to the model developed, optimized values were shown to correspond to the following relative solvent concentrations (ethanol/acetone/ethyl acetate): 0.46/0.00/0.54, 0.93/0.07/0.00, 0.83/0.17/0.00, and 0.64/0.00/0.36, respectively. Comparison to yields obtained by the conventional chloroform/methanol method was carried out. A novel strategy based on the employment of low-toxicity solvents is proposed for the extraction of valuable lipid constituents from octopus waste. A different solvent ratio would be necessary according to the lipid compound concerned.

Safety assessment of fish oil green extraction and in vivo acute toxicity evaluation

Sardine co-products can represent an interesting source of bioactive compounds, such as polyunsaturated fatty acids and in particular omega-3. This study aimed to investigate extraction of oil from sardine co-products by enzymatic hydrolysis using two proteases: commercial Alcalase and protease Bb from a local fungal strain (P2) of Beauveria bassiana, which overproduces proteases. Despite a higher degree of hydrolysis (41.34%) than Alcalase (24.28%), protease Bb allowed the extraction of approximately the same oil content. Resulting oil from both processes had the same fatty acid profile. Interestingly, the all-produced oil displayed an attractive w6/w3 ratio, an indicator of nutritional quality, of the order of 0.16. The safety of the generated oils was also assessed by treating two groups of Wistar rats with the fish oil administered by oral gavage at the doses (30 mg/kg and 300 mg/kg body weight) for 14 days using olive oil as a vehicle. Compared to controls used, both treated groups showed no statistically significant differences. Consequently, the acute oral toxicity evaluated by hematological, biochemical, and histological studies showed the safety of the oil generated using B. bassiana protease.

Comparative Study of Bioactive Lipid Extraction from Squid (Doryteuthis gahi) by-Products by Green Solvents

A novel approach of bioactive lipid extraction by different green solvents was carried out on squid (Doryteuthis gahi) by-products. By-products (viscera, heads, skin, tails, etc.), considered as a single product, were subjected to the following solvent systems: ethanol, acetone, ethyl acetate, 1/1 ethanol/acetone, 1/1 ethanol/ethyl acetate, and 1/1 acetone/ethyl acetate. Analyses carried out included lipid yield, lipid class content, and fatty acid (FA) composition. Results were compared to the lipid extract obtained by the traditional procedure (1/1 chloroform/methanol). Lipid yields obtained by green solvents led to a 33.4−73.2% recovery compared to traditional extraction; the highest values (p < 0.05) were obtained by ethanol-containing systems. Compared to the traditional procedure, ethanol systems showed an 85.8−90.3% recovery of phospholipid compounds and no differences (p > 0.05) in the ω3/ω6 ratio. Green-extracting systems led to higher average values for eicosapentaenoic acid content (15.66−18.56 g·100 g−1 total FAs) and polyene index (1.93−3.29) than chloroform/methanol extraction; differences were significant (p < 0.05) for systems including acetone and ethyl acetate. No differences (p > 0.05) were detected for docosahexaenoic acid content between the traditional procedure and green systems, with all values being included in the 31.12−32.61 g·100 g−1 total FA range. The suitability of EtOH-containing green systems for extraction of bioactive lipid compounds from squid by-products was concluded.

Optimisation of Healthy-Lipid Content and Oxidative Stability during Oil Extraction from Squid (Illex argentinus) Viscera by Green Processing

Green extraction was applied to Argentinean shortfin squid (Illex argentinus) viscera, consisting of a wet pressing method including a drying step, mechanic pressing, centrifugation of the resulting slurry, and oil collection. To maximise the oil yield and ω3 fatty acid content and to minimise the oil damage degree, a response surface methodology (RSM) design was developed focused on the drying temperature (45-85 °C) and time (30-90 min). In general, an increase of the drying time and temperature provided an increase in the lipid yield recovery from the viscera. The strongest drying conditions showed a higher recovery than 50% when compared with the traditional chemical method. The docosahexaenoic and eicosapentaenoic acid contents in the extracted oil revealed scarce dependence on drying conditions, showing valuable ranges (149.2-166.5 and 88.7-102.4 g·kg^-1 oil, respectively). Furthermore, the values of free fatty acids, peroxides, conjugated dienes, and ω3/ω6 ratio did not show extensive differences by comparing oils obtained from the different drying conditions. Contrary, a polyene index (PI) decrease was detected with increasing drying time and temperature. The RSM analysis indicated that optimised drying time (41.3 min) and temperature (85 °C) conditions would lead to 74.73 g·kg^-1 (oil yield), 1.87 (PI), and 6.72 (peroxide value) scores, with a 0.67 desirability value.

Nutritional and Healthy Value of Chemical Constituents Obtained from Patagonian Squid (Doryteuthis gahi) By-Products Captured at Different Seasons

This study focuses on the extraction of nutritional and healthy constituents of whole by-products resulting from the commercialisation of Patagonian squid (Doriteuthis gahi). By-products corresponding to squid individuals captured at different seasons were comparatively analysed for proximate composition, lipid classes content, fatty acid (FA) profile, and macroelement and trace element composition. As a result, moisture, lipid, protein, and ash values were included in the ranges 829.0-842.8, 17.5-21.8, 106.0-123.7, and 9.3-13.3 g·kg^-1 by-products, respectively. Phospholipids showed to be the most abundant lipid class (359.2-463.5 g·kg^-1 lipids), while triacylglycerols were only present in a 9.5-13.1 g·kg^-1 lipids range. Valuable levels were detected for α-tocopherol (539.6-973.3 mg·kg^-1 lipids), polyunsaturated fatty acids (PUFA; 50.5-52.6 g·100 g^-1 FA), ω3 PUFA (47.0-48.6 g·100 g^-1 FA), PUFA/saturated FA ratio (1.4-1.6), and ω3/ω6 ratio (12.1-13.4). Among macroelements, S, P, and Na showed to be more abundant than K, Mg, and Ca. Profitable levels of Co, Cu, Fe, Mn, Se, and Zn were detected in all kinds of individuals. In spite of content variations found as a result of the capture season of Patagonian squid individuals, whole by-products of this cephalopod species can be considered as a profitable source to provide the food and pharmaceutical industries with useful value-added constituents.

Seasonal Changes in Free Amino Acid and Fatty Acid Compositions of Sardines, Sardina pilchardus (Walbaum, 1792): Implications for Nutrition

The aim of this study was to clarify the seasonal variation in the proximate composition of the free amino acid (AA) and fatty acid (FA) profiles of the European sardine (Sardina pilchardus) from the Adriatic Sea and to better understand the nutritive value needed to organize more effective industrial processing, aquaculture use and to ensure the health benefits for consumers through available bioactive compounds such as omega-3 FA and essential AA. The lipid content ranged from 1.18 to 10.58% during the year, being the highest from July to September. For the first time, this paper reports the monthly variation in AA content in sardines. The highest total AA content was measured during the winter period, from January (843 mg/100 g fillet) to March (953 mg/100 g) with histidine, arginine and threonine being the most dominant. The total content of essential free AA (histidine, threonine, valine, methionine, isoleucine, leucine, phenylalanine, tryptophan and lysine) ranged from 137 to 571 mg/100 g fillet (wet weight), recorded in May and March, respectively. The fatty acid profile analyses revealed the major saturated FA as palmitic (C16:0), followed by myristic (C14:0), and stearic (C18:0) acids, and the predominant monosaturated FA as oleic (C18:1n–9) and palmitoleic (C16:1n–7). The high concentrations of polyunsaturated FA in sardines were omega-3 FA, particularly eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 20:6n-3) FA. From July to September, their content was the highest (>3.5 g/100 g of sardine fillets), confirming that these species are excellent sources of bioactive lipids.

Sex and seasonal variation in proximate composition and fatty acid profile of Scomber scombrus (L. 1758) fillets from the Middle East Coast of Tunisia

This study investigates the impact of season and sex variations on the total lipid contents and fatty acid composition of Scomber scombrus fillets from the Middle East Coast of Tunisia in order to dertermine the most favorable periods for consumption, and to see if the nutritional quality of the meat depends on the sex of the animal. The effect of fishing season induced significant changes in the lipid profile, and the highest values for total lipids were obtained in the spring for females with 13.2% and for males with 18.9%. The highest values for proteins were obtained in the summer for females with 22.0% and for males with 21.8%. Protein content variations were not significant (p > 0.05). The n-3/n-6 ratio showed a significant level, indicating a tendency toward n-3 fatty acid accumulation in mackerel fillets mainly represented by DHA, whose values were high during the study period for both sexes, except in autumun, which is the period of mackerel gonad maturation, when DHA decreased significantly (p < 0.05), reaching 23.2 and 34.0% for males and females, respectively. It was concluded that Scomber scombrus has high levels of proteins, lipids, and fatty acid contents mainly n-3 PUFA. DHA sex variations were not significant (p > 0.05). The Atherogenicity index (AI) and Thrombogenicity index (TI) were calculated. In our study the AI index was comprised between 0.3 and 0.6 for males and between 0.4 and 0.5 for females. The TI index values ranged from 0.6 to 0.8 for males, and was about 0.6 for females.

Production of Thermostable T1 Lipase Using Agroindustrial Waste Medium Formulation

Large-scale production of T1 lipase using conventional culture media is costly. To reduce the cost of production, an alternative growth medium using local resources has been developed. In this study, the growth of recombinant Escherichia coli and expression of T1 lipase were tested using different agroindustrial wastes as carbon and nitrogen sources by conventional method. Subsequently, by using central composite rotatable design (CCRD), a set of 30 experiments was generated to evaluate the effect of different parameters, including the amount of molasses (as carbon source), fish waste (as nitrogen source), NaCl, and inducer concentration on production of T1 lipase. Response surface methodology (RSM) analysis indicated that all factors had significant effects on T1 lipase production. This statistical analysis was utilised to develop a quadratic model to correlate various important variables for the growth of the recombinant strain and regulation of gene expression to the response (T1 lipase activity). Optimum conditions for T1 lipase production were observed to be 1.0 g/L of molasses, 2.29 g/L of fish waste, 3.46 g/L of NaCl, and 0.03 mM of IPTG (Isopropyl β-d-1-thiogalactopyranoside). Based on these conditions, the actual lipase activity was found to be 164.37 U/mL, which fitted well with the maximum predicted value of 172.89 U/mL. Therefore, the results demonstrated that, the statistical analysis, performed using RSM, was efficient in optimising T1 lipase production. Moreover, the optimum conditions obtained can be applied to scale up the process and minimise the cost of enzyme production.

The smooth-hound lipolytic system: Biochemical characterization of a purified digestive lipase, lipid profile and in vitro oil digestibility

In order to identify fish enzymes displaying novel biochemical properties, we choose the common smooth-hound (Mustelus mustelus) as a starting biological material to characterize the digestive lipid hydrolyzing enzyme. A smooth-hound digestive lipase (SmDL) was purified from a delipidated pancreatic powder. The SmDL molecular weight was around 50kDa. Specific activities of 2200 and 500U/mg were measured at pH 9 and 40°C using tributyrin and olive oil emulsion as substrates, respectively. Unlike known mammal pancreatic lipases, the SmDL was stable at 50°C and it retained 90% of its initial activity after 15min of incubation at 60°C. Interestingly, bile salts act as an activator of the SmDL. It's worth to notice that the SmDL was also salt-tolerant since it was active in the presence of high salt concentrations reaching 0.8M. Fatty acid (FA) analysis of oil from the smooth-hound viscera showed a dominance of unsaturated ones (UFAs). Interestingly, the major n-3 fatty acids were DHA and EPA with contents of 18.07% and 6.14%, respectively. In vitro digestibility model showed that the smooth hound oil was efficiently hydrolyzed by pancreatic lipases, which suggests the higher assimilation of fish oils by consumers.

Fish processing wastes for microbial enzyme production: a review

Fishery processing industries generate large amounts of by-products. The disposal of these wastes represents an increasing environmental and health problem. To avoid wasting these by-products, various disposal methods have been applied including, ensilation, fermentation, hydrolysate and fish oil production. Interestingly, fish by-products provide an excellent nutrient source for microbial growth useful in enzyme production process, which is largely governed by the cost related to the growth media. Fish wastes (heads, viscera, chitinous material, wastewater, etc.) were prepared and tested as growth substrates for microbial enzymes production such as protease, lipase, chitinolytic and ligninolytic enzymes. This new approach described in this review can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of microbial enzyme production.

Optimization of marine waste based-growth media for microbial lipase production using mixture design methodology

Lipase production by Staphylococcus xylosus and Rhizopus oryzae was investigated using a culture medium based on a mixture of synthetic medium and supernatants generated from tuna by-products and Ulva rigida biomass. The proportion of the three medium components was optimized using the simplex-centroid mixture design method (SCMD). Results indicated that the experimental data were in good agreement with predicted values, indicating that SCMD was a reliable method for determining the optimum mixture proportion of the growth medium. Maximal lipase activities of 12.5 and 23.5 IU/mL were obtained with a 50:50 (v:v) mixture of synthetic medium and tuna by-product supernatant for Staphylococcus xylosus and Rhizopus oryzae, respectively. The predicted responses from these mixture proportions were also validated experimentally.