On the possible effects of harvesting season and chilled storage on the fatty acid profile of the fillet of farmed gilthead sea bream (Sparus aurata)

This work examines the fatty-acid profile of the total lipids of the muscle, as the main edible portion, of farmed sea bream (Sparus aurata) harvested at different periods of the year and subjected to a chilled-storage process (4 °C) for one week. Neither of the variables tested (harvest period, chilled-storage time) significantly affected the quality of this nutritional component, constituting a certain guarantee of its marketability, at least with regard to this aspect of overall product quality.     

Muscle tissue structural changes and texture development in sea bream, Sparus aurata L., during post-mortem storage

Sea bream, Sparus aurata L., specimens were studied in pre-rigor (3 h) and during the following post-mortem days: 1, 5, 10, 15 and 22. Muscle and textural parameters were evaluated on 6 specimens/stage. Structural results showed scarce fibre-to-fibre detachment on pre-rigor, which increased during the post-mortem degradation. Ultrastructural changes revealed rapid muscle degradation. In pre-rigor myofibrils were detached to both sarcolemma and endomysium. Intermyofibrillar spaces increased and some mitochondriae and sarcoplasmic reticulum were swollen. After 1 day, the sarcolemma appeared occasionally disrupted and the interfibrillar spaces increased. From 5 to 10 days, the I-band and Z line presented some alterations, although these were more severe at 15-22 days. Thus, in these two last stages, loss of I-band, Z line and actin filaments was observed, that coincides with the alteration of the hexagonal arrangement in these advanced stages. Also, the fragmentation of myofibrils increased from 5 to 10 days on. Sarcolemma and endomysium were gradually disrupted throughout the post-mortem stages with total loss at 22 days. Consequently, the interfibrillar spaces increased at last stages. Autophagic mechanisms increased from 5 days on, with an intense destruction of all the intracytoplasmic organelles. Textural parameters decreased from pre-rigor until 5-10 days, mainly associated to detachment of myofibers to sarcolemma-endomysium.     

Freshness assessment of gilthead sea bream (Sparus aurata) by machine vision based on gill and eye color changes

The fish freshness was evaluated using machine vision technique through color changes of eyes and gills of farmed and wild gilthead sea bream (Sparus aurata), being employed lightness (L^*), redness (a^*), yellowness (b^*), chroma (c^*), and total color difference (ΔE) parameters during fish ice storage. A digital color imaging system, calibrated to provide accurate CIELAB color measurements, was employed to record the visual characteristics of eyes and gills. The region of interest was automatically selected using a computer program developed in MATLAB software. L^*, b^*, and ΔE of eyes increased with storage time, while c^* decreased. The a^* parameter of fish eyes did not show clear a trend with storage time. The L^*, b^*, and ΔE of fish gills increased with storage time, but a^* and c^* decreased. Regression analysis and artificial neural networks approaches were used to correlate the eyes and gills color parameters with the time of storage and a strong correlation was found between color parameters and storage day. Gills color changes were more precise than those found for eyes in order to evaluate the fish freshness. However, the gills cover should be removed for taking the images and thus, the method is destructive and time-consuming. Therefore, the color parameters of fish eyes can be used as a green, low cost and easy method for fast and on-line assessing of fish freshness in food industry.     

Freshness monitoring of sea bream (Sparus aurata) with a potentiometric sensor

Freshness in one of the main quality attributes for fish commercialization and consumption. The traditional method for fish freshness evaluation is sensory analysis. However, instrumental methods such as electrical, texture and colour measurements, image analysis, VIS spectroscopy and electronic noses have been widely studied as objective alternatives. Each of these methods has advantages and disadvantages, but none of them can be universally proposed for defining and measuring fish freshness.     

Antibacterial and anti-PAF activity of lipid extracts from sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata)

The anti-PAF and the antibacterial activities of lipid extracts obtained from cultured sea bass (Dicentrarchus labrax) and cultured gilthead sea bream (Sparus aurata) were evaluated. Total lipids of sea bass and gilthead sea bream exerted PAF-like activity while, in higher amounts they inhibited this PAF activity. Neutral lipids of both sea bass and gilthead sea bream contained only PAF antagonists while the polar lipid fractions contained both PAF antagonists and agonists. Total lipids of sea bass exhibited stronger PAF-like activity than did those of gilthead sea bream; however, neutral lipids of sea bass contained stronger PAF antagonists than did gilthead sea bream.     

In vivo anti-atherogenic properties of cultured gilthead sea bream (Sparus aurata) polar lipid extracts in hypercholesterolaemic rabbits

The aim of this study was to investigate whether the fish lipid extracts have in vivo anti-atherogenic properties in hypercholesterolaemic rabbits. Fish oil extracts were obtained from cultured gilthead sea bream (Sparus aurata) and, for the in vivo experiment, 12 healthy male New Zealand rabbits of specific weight and age were used, which were randomly divided into two groups of six animals each and were given specific diets for 45 days. Group A was given an atherogenic diet, while group B was given an atherogenic diet enriched with Gilthead Sea Bream Polar Lipids (GSBPL).     

Muscle tissue structure and flesh texture in gilthead sea bream, Sparus aurata L., fillets preserved by refrigeration and by vacuum packaging

Fillets were analysed from 66 gilthead sea bream specimens (Sparus aurata L). Thirty-six fillets were refrigerated (2 °C). The rest of the fillets were vacuum-packed and refrigerated. Muscle and sensorial parameters were evaluated for 22 days post-mortem.Textural parameters were higher in early stages. The refrigerated fillets had the lowest values. Most of textural parameters showed a negative correlation with the detachments among fibres in both groups.Ultrastructural results in vacuum-packed fillets showed that sarcolemma-endomysium was gradually disrupted, with almost a complete loss at 22 days. Initially, the detachments of myofibrils from the sarcolemma-endomysium were scarce. Mitochondria and sarcoplasmic reticulum were swollen from the first stages onwards. From 16 days onwards, the intra-cytoplasmic organelles were significantly altered and the smooth reticulum appeared hypertrophied, indicating an increase of the autophagic mechanisms. Sarcomeres were gradually altered, mainly at the I-band level, which showed a loss of actin filaments and Z-line disruptions from 12 to 16 days onwards.In non-vacuum fillets the muscle tissue was already markedly altered from the early stages. From five days onwards, the detachments of myofibrils from the sarcolemma were frequent and the hypertrophied smooth reticulum and the degraded lysosomes were already observed.     

Effects of olive pomace and olive pomace oil on growth performance,fatty acid composition and cardio protective properties of gilthead sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax)

Gilthead sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were fed with two experimental diets: olive pomace diet and olive pomace oil diet, in order to examine whether fish oil substitution in fish feeds by olive oil production wastes, such as olive pomace and olive pomace oil, has an influence on growth performance, fatty acid composition and cardio protective properties of fish. Gilthead sea bream fed with both experimental diets exhibited satisfactory growth performance factors while sea bass did not. The total lipids of gilthead sea bream fed with olive pomace diet contained statistically decreased levels of fatty acids, while exhibited the most potent biological activity against platelet aggregation induced by Platelet Activating Factor. These data indicate that olive pomace can be used as a partial substitute of fish oil in fish feed improving its cardio protective properties.     

Effects of dietary lipid source on fillet chemical composition,flavour volatile compounds and sensory characteristics in the freshwater fish tench (Tinca tinca L.)

In this study the effects of soybean and linseed oils on chemical and sensory characteristics of fillets were evaluated in the freshwater fish tench (Tinca tinca L.). Five experimental diets, differing only in the relative amount of soybean and linseed oil, were formulated and the experiment was conducted on 360 sub-adult tench for 12 weeks. The fatty acid composition of muscle reflected that of the diets and significant correlations were observed. Diets containing higher amounts of n − 6 fatty acids were responsible for an increased level of n − 6 fatty acids in the fish flesh. Consequently, an increase in the relative amount of n − 6-derived volatile aldehydes was also observed. These latter compounds are generally reported to contribute negatively to the general aroma of fish muscle and, consistently, the results of the sensory analysis showed a high value for the “off-flavour” attribute for fish fed the diet containing only n − 6-rich soybean oil.     

Comparison of antiatherogenic properties of lipids obtained from wild and cultured sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata)

The aggregatory properties of lipid fractions, obtained from wild and cultured specimens of sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) were studied. The total lipids were extracted and separated into polar and neutral lipids. The polar lipids and neutral lipids were further separated by thin layer chromatography and the fractions obtained were tested for their ability to aggregate platelets or inhibit the platelet-activating factor (PAF)-induced aggregation. The aggregatory properties of the lipid fractions were dependent on the fish species and whether the fish samples were wild or cultured. The lipid fractions extracted from wild gilthead sea bream showed strong aggregatory properties, while the lipid fractions extracted from farmed fish showed strong inhibitory activities. The aggregatory properties of total lipids were mainly attributed to polar lipids while the PAF antagonistic activity was attributed to neutral lipids. The biological activities of such fractions with respect to their aggregatory properties may explain, in part, the protective role of fish consumption against cardiovascular diseases.     

Effects of frying on the fatty acid composition in farmed and wild gilthead sea bream (Sparus aurata)

The effects of frying in soybean (FWSO) and olive oils (FWOO) on the fatty acid composition of farmed and wild gilthead sea bream Sparus aurata were evaluated. The fat content increased with both frying treatments. However, after FWOO the moisture content of the fish was reduced to a greater extent than that in fish FWSO. The concentration of saturated fatty acids (SFA) decreased significantly during both frying processes ( P  < 0.01). However, the concentration of monounsaturated fatty acids (MUFA) increased significantly in fish fried in olive oil ( P  < 0.01). The fried fish contained a higher level of n-6 polyunsaturated fatty acids (PUFA) and a lower level of n-3 PUFA compared to raw fish. The n-3/n-6 ratio decreased in wild fish FWSO and FWOO from 0.94 ± 0.08 to 0.15 ± 0.01 and 0.15 ± 0.02, respectively. In farmed bream, the ratios decreased from 2.51 ± 0.03 to 0.18 ± 0.03 and 0.36 ± 0.01, respectively. The concentration of trans fatty acids decreased significantly in both fish types after frying ( P  < 0.05). The frying process widely affected the EPA and DHA content, limiting the positive effects of n-3 PUFA.     

Seasonal changes in the fillet fatty acid profile and nutritional characteristics of wild Trasimeno Lake goldfish (Carassius auratus L.)

Goldfish (Carassius auratus L.) is very diffuse in Trasimeno Lake, and show great adaptability and have become a dominant fish of the lake ecosystem. The aim of this study was to evaluate the seasonal effect on the fatty acid profile and nutritional characteristics of goldfish caught in Trasimeno Lake. Forty fillets per season were used to evaluate the respective proximate composition, fatty acid profile, nutritional indices and protein and lipid oxidative stability. Season significantly affected the chemical traits of the fillets. A lower level of SFA was observed during spring, while a higher proportion of MUFA was observed during the winter. PUFA exceeded 50% of the total fatty acids content during the autumn, spring and summer. The nutritional indices were very good in comparison to those observed in other livestock animals. Goldfish fillets are characterised by a high nutritional value and good oxidative stability; the best results of this study were obtained in autumn and spring fillets.     

Changes in fatty acid and essential oil composition of sage (Salvia officinalis L.) leaves under NaCl stress

Fatty acids and essential oils from hydroponically cultivated Salvia officinalis leaves were analyzed by GC and GC–MS. Four different levels of NaCl (25, 50, 75 and 100 mM) were applied. The first results showed that salt treatment reduced significantly the plant growth by 61% and the total fatty acids (TFA) content by 32% at 100 mM NaCl. Alpha-linolenic, gadoleic, palmitic and oleic acids were the major fatty acids. Moreover, the polyunsaturated fatty acids decreased, while the monounsaturated ones increased with respect to increasing salinity. Regarding the essential oil composition, the main compounds were α-and β-thujone, 1,8-cineole, camphor, α-humulene, viridiflorol and manool at all salt treatments. The yield had a maximum increase at 75 mM NaCl. Hence, sage can be considered as moderately salt sensitive.     

Effect of smoking on quality parameters of farmed gilthead sea bream (Sparus aurata L.) and sensory attributes of the smoked product

The effect of smoking on the proximate composition, chemical parameters and microbial loads of farmed gilthead sea bream (Sparus aurata L.), as well as the sensory attributes of the smoked product were investigated. The process reduced the moisture content and the total aerobic count and increased the protein, lipids and total volatile basic nitrogen content and the thiobarbituric acid number . The values of the last two parameters were much lower than acceptable limits reported in the literature references for smoked fish products. No effect was noted on the fatty acid composition of total lipids. The new product was highly acceptable to laboratory and consumer panels.Kyriakos Vareltzis deceased     

The effect of replacing dietary fish oil with canola oil on fatty acid composition and expression of desaturase and elongase genes in Jade Tiger hybrid abalone

This study investigates the effect of graded substitution of dietary fish oil (FO) with canola oil (CO) on fatty acid composition and expression of Δ-6 desaturase and elongase 2 genes in the muscle of Jade Tiger hybrid abalone. The control diet contained 1.5% FO supplement (0% CO). Four other diets contained FO/CO in ratios of 3:1 (CO 25%), 1:1 (CO 50%), 1:3 (CO 75%) and 100% CO. The result demonstrated that abalone fed the diets supplemented with 25% and 50% CO showed similarly high levels of total omega-3 polyunsaturated fatty acid (n-3 PUFA), eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) (P < 0.05) as the 0% CO group. The highest levels of total PUFA and total monounsaturated fatty acids were found in the 100% CO group (P < 0.05). The results also showed that Δ-6 desaturase and elongase 2 gene expression was increased in a graded manner by increasing dietary CO (P < 0.05). It was concluded that replacement of FO by CO at the levels of 25-50% can improve the contents of health-benefiting EPA and DHA in abalone.     

内蒙古地区蓖麻材料种子中脂肪酸组成的测定及分析

采用索氏提取法、毛细管气相色谱法,首次对内蒙古地区8个品种、4个品系共12个蓖麻材料种子中的粗脂肪含量、脂肪酸组成进行测定,用IMB SPSS Statistics 19软件对数据进行分析,为内蒙古地区蓖麻高油品质育种研究及化工原料的选择提供参考数据。试验结果表明:12个蓖麻材料的种子百粒质量、种仁百粒质量、种仁率、百粒种子中粗脂肪含量、种子中粗脂肪含量、种仁中粗脂肪含量差异均达到极显著水平;蓖麻油酸是蓖麻粗脂肪的主要成分;12个材料的粗脂肪中8种脂肪酸含量、种子中8种脂肪酸含量差异均达极显著水平;基于种子中粗脂肪含量和种子中8种脂肪酸含量进行聚类的结果不相同,基于种子中8种脂肪酸含量和种子中蓖麻油酸含量进行聚类的结果基本一致。对种子中粗脂肪含量和8种脂肪酸含量进行线性回归分析,从回归方程可以看出,种子中的粗脂肪含量与硬脂酸、花生酸、亚油酸、蓖麻油酸含量呈正相关,与棕榈酸、油酸、亚麻酸、花生一烯酸含量呈负相关。     

不同大小蓖麻籽中脂肪酸组分的测定与分析

以32个品种不同大小的蓖麻籽为研究对象,采用索氏提取法、毛细管气相色谱法对籽中粗脂肪含量、脂肪酸组分进行测定分析,研究籽的大小与含油量之间的关系,为蓖麻高油品质育种研究提供依据。结果表明,32个品种的籽在长、体积、容重、百粒质量方面差异均极显著;籽中的粗脂肪、蓖麻油酸含量差异极显著。籽中粗脂肪含量和大小指标的多元回归方程:y_1=(-5.156x_1-8.747x_2+1.977x_3+0.324x_4+44.462)×100%;籽中蓖麻油酸含量和大小指标的多元回归方程为:y_2=(2.282x_1-19.553x_2+2.448x_3+0.286x_4+32.147)×100%。     

Quality loss during the frozen storage of sea salmon (Pseudopercis semifasciata). Effect of rosemary (Rosmarinus officinalis L.) extract

Lipid and protein alterations during the frozen storage (−11 °C) were analyzed in minced sea salmon muscles to evaluate the effect of the application of rosemary extract (200 and 500 mg/kg). Lipid oxidation reached maximum TBA values between 3 and 4 months of storage in untreated muscles. The main polyunsaturated fatty acids affected were 22:6-ω3, 22:5-ω3 and 20:4-ω6 acids. Phospholipid hydrolysis was also detected. Rosemary extract reduced lipid oxidation for 6 months (500 mg/kg, muscle with 10.8 g/kg lipids) or 3 months (200 mg/kg, muscle with 5.3 g/kg lipids). Myofibrillar proteins showed a decrease of extractability (80%) after 2 months of storage. Myosin denaturation was evident by DSC at 3 months, while myosin and actin peaks disappeared at 6 months. A diminution of extractable polypeptides of high molecular weight was recorded by SDS-PAGE after 3 months. The available lysine content suffered a reduction starting at 3 months of storage, suggesting some interaction involving the free amino groups of lysine. Fluorescent compounds' determination did not show changes due to the interaction of lipid oxidation products and proteins, while protein alterations could not be reduced by the rosemary extract. Furthermore, the antioxidant reduced the loss of red color in the muscle.     

Variability of fatty acid content in pumpkin seeds (Cucurbita pepo L.)

Pumpkin (Cucurbita pepo L.) seed oil is a common salad oil which is produced in Slovenia, Hungary and the southern parts of Austria. It is dark green and has a high content of free fatty acids. The seed itself can be eaten. Due to its colour and the foam formation, the oil cannot be used for cooking. The content of vitamin E, especially-tocopherol, is very high. The oil content of the pumpkin seed is about 50%. The variability in the oil content is very high resulting from a broad genetic diversity. Thus a breeding programme for increasing the oil productivity is very promising. The four dominant fatty acids are palmitic, stearic, oleic and linoleic acids. These four fatty acids make up 98±0.13% of the total amount of fatty acids, others being found at levels well below 0.5%.     

Chemical,amino acid and fatty acid composition of Sterculia urens L. seed

The chemical, amino acid and fatty acid compositions of Sterculia urens seeds are reported. The cotyledons were found to be rich in protein (30.88%) and lipids (39.2%). The major amino acids in defatted Sterculia urens cotyledon flour (DSCF) were determined as glutamic acid, arginine and aspartic acid. Cysteine, methionine, tyrosine and histidine were observed in minor quantities. The ratio of essential to non-essential amino acids was observed to be 0.45. Among the essential amino acids, isoleucine was found to be higher than the reported FAO/WHO requirements. The GC-FID and GC–MS analysis revealed that the major fatty acids of the total lipid were stearic acid (31.72%), linoleic acid (28.83%) and palmitic acid (26.79%). Eicosadienoic acid (4.98%) and eicosatrienoic acid (2.96%) were also found in the total lipid.