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This investigation was aimed to assess and evaluate the effect of frying process with three different oils (corn, olive and margarine) on fatty acids and lipid classes’ composition of clam and their impact on the nutritional value and tissues quality. The results indicated that the contents of saturated, monounsaturated and polyunsaturated fatty acids varied significantly in fried clams and frying oil. Our data demonstrated that all lipid classes’ contents increased significantly after all frying processes. It was concluded that the frying process decreased the n-3/n-6 and DHA+EPA and increased the levels of atherogenic; thrombogenic indices. Additionally, these culinary processes promoted lipid peroxidation through the enhancement of TBARs, PV and FFA. These changes were more significant and intensive after frying with margarine and corn oils followed by virgin olive oil. These results suggest that clam fried with olive oil can be classified as highly nutritive in regard to its lipid content, major fatty acid profile; and nutritional value.

In order to increase the low-temperature resistance of Nile tilapia, the purpose of this study was to determine the potential effect of ω3 fatty acid incorporation in Oreochromis niloticus diet. To perform this, two experimental diets containing soybean oil (D1) and cod liver oil (D2) have been supplied to juvenile tilapia for 30 days. According to our results, similar improvements in the two diets have been recorded for growth performance of O. niloticus including the final body mass, specific growth rate, and feed conversion ratio. Our results showed that fish fed with diet D2 promoted high polyunsaturated fatty acids mainly n-3 series (PUFA (n-3)) percent, highlighting the increased levels of docosahexaenoic (DHA) and eicosapentaenoic (EPA) as well as the activation of their conversion enzyme ratios D5D and D6D desaturases. The second objective was to assess the effect of the two experimental diets on low water temperature tolerance. This was done by exposing juvenile fish at the end of the first experiment to 16, 14, 12, 10, and 8 °C for 12 h, 24 h, and 48 h. The sub-lethal LT

The effect of storage time (5, 10 and 15 days) and temperature (− 20 °C and + 4 °C) on the biochemical composition of the Tunisian mussel (Mytilus galloprovincialis) was evaluated by investigating changes in proximate composition, fatty acids, minerals and nutritional quality indices. Lipid and protein degradations were also evaluated through several markers of oxidative damage. Results showed a significant decrease in the biochemical compounds in mussel tissues after both refrigeration and freezing processes (p

Biochemical composition and fatty acid profile of raw Ark shells (RA) were compared to Ark shells submitted to three different cooking methods (BA: baking in the oven; PF: pan-frying in butter and MW: cooking in a microwave). Moisture (%) was significantly higher in RA (79.66) with respect to PF (65.09), BA (48.63) and MW (47.02). Protein (mg/g of flesh) decreased significantly from 18.62 in RA to 15.40 in MW, 13.76 in PF and 13.33 in BA. However, lipids significantly increased in MW (43.32 mg/g of flesh) and PF (63.63 mg/g of flesh) with respect to RA (35.05 mg/g of flesh). Pan-frying affected considerably triacylglycerol (TAG) and the fatty acid composition (FA) of Ark shell flesh. The most changes occurred in saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acid fractions after this process. The n-3 PUFA decreased significantly from RA (16.40 mg/g dry weight) to PF (10.02 mg/g DW). While, the opposite trend was observed for n-6 PUFA, revealing that this cooking method had considerable effects on the nutritional characteristics of this edible shellfish. The analysis of lipid peroxidation markers such as thiobarbituric acid reactive substances, free fatty acid and peroxide value confirmed that both heat treatment and time of cooking caused lipid degradation, which had been more accentuated during pan-frying treatment. For the populations who consume Ark shells occasionally or frequently, baking and microwave cooking could be then considered as wiser and healthier cooking methods since they conserve better the nutritional value of this marine product. The present study will be of practical value from a health perspective for Mediterranean populations.

The present work aims to determine and compare the tolerance to different stress environmental conditions in two crabs’ species the native Carcinus aestuarii and the invasive Portunus segnis. In this study, C.aestuarii appeared more intolerant to environmental stressor as shown by the important changes occurred on the proximate, fatty acids and their essential compounds comparing to P.segnis. Our results revealed accumulation of metallic trace elements, macromolecular damages and antioxidant defense systems perturbations mostly in C.aesuarii gills and muscles than P.segnis, thus highlighting the importance of a multi-markers approach to assess the urban pollution in coastal ecosystems. According to this study, fatty acid profiles and oxidative stress biomarker examination of both crabs indicate that the different environmental stresses significantly influence the tolerance of C.aestuarii compared to the invasive P.segnis which may provide physiological advantages for the achievement of their invasion in novel ecosystems.

The present study aimed to evaluate the biochemical status of Venerupis decussata collected seasonally from two Tunisian coastline lagoons (Ghar El Melh and Boughrara) submitted to different anthropogenic levels. Trace elements were significantly higher in clams from Boughrara, especially during the warm season. Fatty acids, proximate compositions, and nutritional value of both clam populations were higher, appearing to be the best for human consumption principally during the spring season. The principal component analysis was determined, including phospholipids and reserve lipids, revealing a great variation with the exogenous and endogenous factors. Generally, clams from Boughrara had a significant alteration in biochemical composition principally due to the anthropogenic levels and physicochemical fluctuation of this lagoon. Our results reflected the healthy benefit of clam consumption and the use of energy reserves and essential fatty acids as a great biomarker to assess ecological risk in lagoons and other coastal ecosystems.

This study aimed to determine the effect of cadmium pollution on some life history traits of Porcellio laevis populations sampled along a contamination gradient in the region of Sfax (central Tunisia). To characterize each population, woodlice were collected in the spring and parameters such as the number of individuals, sex-ratio, body length and cephalothorax width of the different categories of individuals were determined. Since the sampling period coincided with the reproduction period of the species, number and diameter of eggs, embryos, and mancas were counted and measured for ovigerous females of each of the studied population. Relative growth was estimated using a morphometric relationship between the body length and the cephalothorax width to determine the type of relationship (isometric/allometric). The number of eggs, embryos and mancas varied between the sampled populations and ranged between 13.25 ± 7.18 and 58.85 ± 36.37; 25 ± 8.71 and 40.9 ± 11.47; 11.5 ± 7.77 and 29 mm, respectively. The mean size of eggs, embryos and mancas ranged between 0.491 ± 0.077 and 0.558 ± 0.098 mm, 0.697 ± 0.070 and 0.918 ± 0.206 mm, and 0.945 ± 0.248 and 1.554 ± 0.236 mm, respectively. Body length, cephalothorax width, eggs and embryos sizes, were lower in the population sampled from the most polluted site compared to the other populations. Additionally, based on the Pearson’s correlation, negative and non-significant correlations were found between the number and the size of the different reproductive stages (eggs, embryos and mancas), and cadmium soil content. The morphometric parameters showed a significant correlation between the body length and the cephalothorax width, and globally a negative allometry was observed.

The effect of storage time (5, 10 and 15 days) and temperature (− 20 °C and + 4 °C) on the biochemical composition of the Tunisian mussel (Mytilus galloprovincialis) was evaluated by investigating changes in proximate composition, fatty acids, minerals and nutritional quality indices. Lipid and protein degradations were also evaluated through several markers of oxidative damage. Results showed a significant decrease in the biochemical compounds in mussel tissues after both refrigeration and freezing processes (p

The present study assessed the consequences of environmental changes on the biochemical quality and the physiological condition of the whole body and others organs Mactra stultorum collected from the north coast of Tunisia. Significant variations in the biochemical components, PE and CI have shown between seasons. The depletion of glycogen in all tissues was recorded during spawning periods (late spring and summer). Lipid accumulation in gonad–visceral mass during the early and late gametogenesis stages was associated with the increase in CI and GSI. However, decreases in lipid and protein contents were recorded in all the tested organs during summer when the animals are in the spawning period, suggesting that clams could accumulate proteins and lipids. Regarding the environmental factors, a negative and a significant correlation was recorded between glycogen, lipid contents and water temperature. Based on these results and as M. stultorum is appreciated by the consumers, we suggest that the harvesting of M. stultorum should be concentrated on February to June when the whole body was characterized by an important amount of the biochemical composition when the seafood is at its highest nutritive value as compared to August to January. Because of its high nutritive value especially it’s richness by some important and essentials fatty acids, M. stultorum seems to be considered as an important commercial species in many countries and in Tunisia particularly. We suggest that harvesting of M. stultorum should be concentrated on the period when the seafood is at its highest nutritive value. survivability rates from malignancy. The greatest variations in the mortality ratios existed within the European countries.

This work aims to examine the reproductive cycle of the bivalve Mactra corallina inhabiting the Gulf of Tunis (Tunisia). Histological analysis indicated that the reproductive cycle is composed of s...

Bivalves are known for their high nutritional value and are considered a healthy food for human consumption. The effect of different cooking methods (steaming, boiling, grilling, and frying) on pro...

The invasive Portunus segnis, an atlantic species, was recently recorded in Tunisian waters. Since its record in the Gulf of Gabes, no studies have been carried out about the biochemical analysis of this alien species. In this context, our study aims to evaluate the fatty acid profile, lipid classes (neutral and polar), and nutritional value of breast of this invasive species. Specimens sampled from the gulf of Gabes were found to be rich in protein and oil, with significant differences between sexes. The level of saturated, monounsaturated, and polyunsaturated fatty acids in neutral and polar showed a significant difference between sexes. Saturated fatty acids were significantly higher in male P. segnis compared to the female. Docosahexaenoic (DHA), eicosapentaenoic (EPA), and arachidonic (ARA) were the most predominate polyunsaturated fatty acids (PUFA) in all oil classes. Oleic (C18:1) and Palmitoleic (C16:1) were the most abundant in monounsaturated. Palmitic (C16:0) and Stearic (C18:0) were the major saturated fatty acids. Consequently, the breast of P. segnis was a valuable source of high oil quality: It is rich in essential fatty acids and has an important n-3/n-6 ratio in both male and female blue crab. Therefore, the atherogenicity and the thrombogenicity were also evaluated, showing that P. segnis is a shellfish of greater value for human consumption in Tunisia.

The reproductive strategy of an unexploited population of Arca noae from the salt-water Bizerte Lagoon (Tunisia, western Mediterranean), including its tissue plasticity, was studied. In total 309 individuals, collected monthly from October 2013 to September 2014, were examined; 142 were females, 42 were males and five were hermaphrodites. They were used in histological and immunohistochemical (stem marker: Pou5f1; proliferation marker: proliferating cell nuclear antigen (PCNA)) analyses of gonads and adjacent tissues (N = 189) as well as to compute the monthly condition index (N = 120). Water salinity, temperature and chlorophyll a concentration were recorded. Ripe ovaries were observed in two discrete periods, October–November and April–August. Both gonad ripenings were followed by spawning periods, November–April and July–September. The mature oocyte density showed that the first spawning period was less vigorous than the second one. These data also indicated that A. noae is a multiple spawner. Five cases of protandric hermaphroditism occurred from December to April. Gonad tissue was strictly associated and intermingled with the digestive gland and mantle muscle fibres. Seasonal variations were observed in the relative proportions of digestive gland and gonads: the former predominated when the latter regressed (March) and vice versa (peak in June). Seasonal transitions from germinal to somatic tissue and vice versa were hypothesised to occur through transdifferentiation mechanisms based on the activity of stem and proliferating cells. The condition index roughly increased along with gonad ripening and decreased during the spawning periods, although it did not run parallel to gonad evolution, because it also depended on chlorophyll a concentration, a proxy for phytoplankton density. The condition index was significantly correlated, by multiple regression, to both mature oocyte density and chlorophyll a concentration. Arca noae appears to have evolved a flexible reproductive strategy that makes it capable of exploiting diverse environmental conditions, which also involves tissue transdifferentiation.

The current study examined the concentrations of ten trace elements (TE) (nickel, chromium, cadmium, iron, zinc, manganese, aluminum, copper, selenium and lead) in the edible tissue of the Ark shell Arca noae (L. 1758) from a Mediterranean coastal lagoon, the Bizerte lagoon during 2013–2014. The analysis of several redox status biomarkers, metallothioneins (MTs), malondialdehyde (MDA), glutathione peroxidase (GPx), reduced glutathione (GSH) and acetylcholinesterase (AChE), was monitored as a response to TE bioaccumulation and environmental parameters variability. Significant differences (p

The objective of the present work is to evaluate the possible toxic effect engendered by graded doses of lead chloride (PbCl 2 ) on Mactra stultorum mantle and adductor muscles through a battery of biomarkers responses. M. stultorum were divided into 4 groups and exposed to three concentrations of PbCl 2 (D1:1mg/L, D2: 2.5 mg/L and D3: 5 mg/L) with control during five days. Our findings showed decreases of lipid contents in both organs following PbCl 2 exposure, while, proteins declined only in the adductor muscles of the treated M. stultorum. During our experiment, the PbCl 2 exposure induced the levels of metallothionein (MTs), malondialdehyde (MDA) and advanced oxidation protein products (AOPP) in both organs as compared to the control. These biomarkers responses are distinctly different between mantle and adductor muscles.

This study aimed to provide information about the changes in fatty acid composition and quality in Ruditapes decussatus tissue after four culinary treatments (steamed, baked, grilled and fried). All treated samples showed a significant decrease in moisture and protein. In contrast, a significant increase in fat content resulted from the grilled and fried treatments. Saturated fatty acid was significantly higher in fresh clams than all cooking processes, except in fried ones. Monounsaturated fatty acid and polyunsaturated fatty acid varied significantly between fresh and cooked clams with high values recorded for fried clams. The n-3/n-6 ratio, peroxide index, EPA+DHA and atherogenicity index decreased significantly after the cooking processes particularly in fried clams. The mineral levels (Mg, Ca and Mn) of cooked clams decreased considerably with grilled and fried treatments. The impacts of cooking on the fatty acid composition and protein content in clam tissue was evaluated by lipid peroxidation (TBARS, PV, FFA, TOR) and protein oxidation (AOPP and PCO), which varied statistically in fried, steamed, grilled and baked samples; indicating alterations in cooked clam tissues structure. Based on our results, steaming is recommended for the preparation of clams because it preserves the most nutritional tissue quality.

This study reveals information for the first time about the total lipid (TL) content and fatty acid composition (FA) of Mactra stultorum (M. corallina). Three edible organs (foot, mantle and adductor muscle) were the subjects of this research in order to determine the most favorable periods for their consumption in relation to seasonal variability. The results showed lower lipid content in the adductor muscles in summer (12.73 ± 2.55 mg/g dry matter); while a higher content was observed in winter (28.97 ± 3.50 mg/g dry matter). However, similar lipid contents were observed in the mantle and foot tissues among the seasons. The fatty acid composition of Mactra stultorum adductor muscles, mantle and foot was dominated by saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA). Palmitic acid (16:0) was the major saturated fatty acid (SFA) and reached higher levels during summer in the foot (26%), mantle (21%) and adductor muscles (25%). Among PUFA, eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) showed significant variation among seasons with high levels recorded during winter and spring. Monounsaturated fatty acids (MUFA) did not show any remarkable variation among seasons for the three studied tissues. Seasonal changes in fatty acids were observed for all samples, reaching a maximum level in winter or spring.

Lake and coastal Tunisian areas are rich biodiversity habitats, although little information is available about the distribution of food sources for the inhabitant species. In this study, a fatty acid analysis was used to study the trophic ecology of Venerupis decussatac ommunities from 10 sites located along the Tunisian Coast. The richest population in fatty acids was found in S4 followed by S5 and S8, while that of S1, S3 and S10 were the least rich. Results from multivariate analysis confirmed the ecological position of the studied population based on their fatty acid composition. Our results divided the ten studied populations into three similar groups according to their ecological and geographical positions in relation to environmental parameters and food and trophic links. A principal component analysis revealed that diatoms and dinoflagellates were the predominate diets in all the sampling stations. Bacteria and urban discharge dominated the dietary source of clams from S10 and S9. Zooplankton were the preferred diet of V. decussata harvested from the two S2 and S3 lakes; although green algae, phytoplankton and detritus were absent from the dietary source of the two previous populations. Despite spatial differences, clams from the north and the south could be easily distinguished from each other, which indicates the utility of this method in the dietary analysis of different food chain links. This study proves that geographic, ecologic and abiotic factors as well as their mutual interaction should be properly investigated in studies focusing on the trophic chains of aquatic ecosystems.

The seasonal changes in biochemical composition of the edible bivalveArca noaeharvested from a Mediterranean coastal lagoon (Bizerte lagoon, Tunisia) were investigated from October 2013 to September 2014. Potential food sources and nutritional quality indices (NQI) were determined by analyzing the fatty acid profiles of their tissues during an annual reproductive cycle. Results showed thatA. noaehad moisture (73.8–82%) and protein (24.1–58.6% dry weight) as major components, followed by lipid (10.4–28.8% dry weight) and glycogen (4.05–14.6% dry weight).A. noaeaccumulated lipid and glycogen for gonadal development during both maturation periods (late autumn/late spring–summer) to be used during spawning periods (winter/late summer–early autumn). However, proteins were mainly used to support reproductive allocation and played an important role on the energetic maintenance. Lipid and glycogen were found to be significantly related to temperature, salinity and chlorophylla(p 0.05). An increase of condition index (CI) was observed during spring and early summer when both temperature and food supply increased. The total fatty acid (TFA) profile of Ark shells was dominated by polyunsaturated fatty acids (PUFA) (33.8–49.6%), followed by saturated (SFA) (29.1–43.1%) and monounsaturated fatty acids (MUFA) (20.77–28.3%).A. noaesoft tissues were also rich in macro-minerals (Na, Ca and Mg). The analysis of fatty acid trophic markers revealed that the diet ofA. noaeduring the year of study was based on mixture food mainly on phytoplankton followed by zooplankton and other sources (bacteria, seagrass and macroalgae). Furthermore, the nutritional quality indices have revealed thatA. noaeis an excellent source of nutrients and a healthy food for human consumption. These data are useful to the conservation of natural stocks ofA. noaeand the development of sustainable aquaculture production of this shellfish species in the Bizerte lagoon.