G. Giorgi

Effect of the Inclusion of Dried Tetraselmis suecica on Growth, Feed Utilization, and Fillet Composition of European Sea Bass Juveniles Fed Organic Diets

Dried Tetraselmis suecica was evaluated as a fish protein substitute when incorporated to replace (protein basis) 10% (TETRA10) and 20% (TETRA20) of the control diet. The diets were offered to nine groups of European sea bass (72 g) over 63 days. Test diets did not affect zootechnical performances nor carcass or fillet yields and proximate analysis of edible portion. Feeding TETRA20 resulted in lower apparent digestibility coefficients of protein, lipid, and organic matter, and hepatosomatic index compared to the control diet. T. suecica was able to replace up to 20% of fish protein without hampering growth performance and major quality traits of sea bass.

Lipid, inflammatory and haemorheological profiles are significantly affected by farmed fish eating: an intervention study

Aim The objective of the present study was to evaluate the influence of short-term dietary intake of farmed fish on biomarkers related to the atherosclerotic process. Methods and results Lipid, inflammatory, and haemorheological variables before (T0) and after a dietary intervention with about 800 g Orbetello farmed sea bass per week for 10 weeks (T1) were evaluated in nine dyslipidemic subjects. Fish intake significantly decreased triacylglycerols (T1, 140.2±20.3 mg/dl versus T0, 183.3±29.2 mg/dl; P =0.04), whereas no significant changes for the other lipid variables have been observed. Moreover, dietary intervention significantly (P <0.05) decreased all of the inflammatory parameters investigated; namely, high-sensitivity C-reactive protein, interleukin-6, and interleukin-8. Furthermore, a significant (P =0.04) improvement in erythrocytes’ deformability index was reported after 10 weeks of fish dietary intake (9.0±0.7% versus 5.4±1.0% for T1 and T0, respectively). Conclusion Dietary short-term intake of farmed fish seems to impose favourable biochemical changes in dyslipidemic subjects.

Morphological, nutritional and safety traits of bluefin tuna (Thunnus thynnus) reared in floating cages

To evaluate the influence of fattening on morphological, nutritional and safety characteristics, two lots of bluefin tuna were sampled before (November: 2 ♀, 4 ♂) and after 5 months of fattening (April: 5 ♀, 5 ♂). The specimens, after death, were refrigerated and analysed at different times over the period of a week for morphological and flesh physico-chemical parameters in six muscle sites. Tuna sampled in April had greater body weight (44.04 vs 36.41kg), trunk length (52.21 vs 48.22cm) and minimum and maximum circumferences (13.74 vs 12.77 and 94.90 vs 89.10cm). No differences in other linear measures or body components were found. Fattening did not influence flesh colour or total lipid content, producing small differences in its chemical composition: greater C18:0, C18:1n9 and PUFAn6 percentages; higher putrescine and histamine (0.489 vs 0.335 and 0.666 vs 0.370mg/kg) but lower spermine and spermidine (10.598 vs 17.387 and 2.420 vs 3.928mg/kg) levels. Large differences in physico-chemical parameters were found between muscle sites and a significant interaction between sampling date and muscle site indicated non homogeneous changes in chemical composition of dorsal, ventral and red muscle after fattening. Sex only influenced fat content in viscera (♀ 12.84 vs ♂ 9.84%).

Growth performance and quality traits of mussel (Mytilus galloprovincialis Lamarck) reared in two different sites in Tuscany

Riassunto Prestazioni produttive e caratteristiche qualitative del mitilo (Mytilus galloprovincialis Lamarck) allevato in Toscana in due differenti siti. Mitili della stessa popolazione, alla taglia di 30,3±8,3 mm, sono stati trasferiti in reste ed allevati in sospensione per 231 giorni in due siti della costa meridionale toscana (laguna di Orbetello e mare aperto). I due gruppi sono stati monitorati per i parametri lunghezza, larghezza, spessore, peso, incidenza della conchiglia e della parte edule, composizione chimica della parte edule. Durante la sperimentazione i mitili della laguna hanno presentato migliori performance di crescita. L’incidenza della parte molle è stata soggetta a notevoli variazioni durante il periodo considerato. Variazioni di maggior ampiezza sono state rilevate nei mitili della laguna che, alla fine della sperimentazione, hanno presentato minori resa in cottura e resistenza alla rottura delle valve. Sono state riscontrate differenze nel profilo acidico dei lipidi neutri con un più elevato livello di PUFAn3, per la maggiore percentuale di C18:3n3 e di C18:4n3, e un più basso tenore di MUFA nei mitili della laguna.

Lipid traits and dietary quality of sea bass fillets from Orbetello

The aim of the study was to investigate the possibility of obtaining: a) reliable estimates of sea bass fillet weight and lipid/fatty acid content from simple non destructive morphometric measurements; b) estimates of healthy eating quality evaluation from effects of consumption on blood biomarkers related to atherosclerotic/thrombogenic processes. A series of parameters were measured in 708 fish. Estimates of fillet weight from b.w. and max. thickness (R2=0.96, rsd=±20.55g) and of lipid content from b.w., total length, max. thickness and condition factor (R2= 0.69, rsd=±3.3g) were found to be very reliable; flesh n-3 PUFA and EPA content were also estimated from condition factor and max. girth (R2=0.32, rsd=±0.42g; R2=0.38, rsd=±0.13g). Flesh healthy eating quality was evaluated from changes in blood biomarkers (lipid profile, inflammatory markers, haemorheological profile) in dyslipidemic subjects who had eaten fillets three times a week for 10 weeks. A weekly flesh intake of 807g increased erythrocyte n-3 PUFA (P<0.05) and decreased triglycerides (P<0.008), interleukin-6 (P<0.03), interleukin-8 (P<0.04), Whole Blood Viscosity 20.400 (P<0.04) and erythrocyte filtration (P<0.008). Short term intake of sea bass therefore seemed associated with favourable biochemical changes in dyslipidemic subjects, as reflected by lower circulating levels of markers of atherosclerosis.

Quality traits of Procambarus clarkii (girard) related to sex and refrigerated storage

Abstract The red swamp crayfish (Procambarus clarkii, Girard) is the most widespread alien species in Europe. Imported from Louisiana to southern Spain in 1973, where at present it is reared in crayfish farm and also diffused in the wild, it was introduced into Italy in the ’80s and is now well established in natural environments of northern and central Italy. Naturalization of this alien species poses risks for aquatic ecosystems and its use as food may be a way to limit its spreading. The aim of this study was to analyse the morphological, mercantile and biochemical characteristics of male and female specimens of Procambarus clarkii and to evaluate changes in qualitative traits during refrigerated storage. Specimens of red swamp crayfish collected in a river, after a rearing period of 85 days in tanks, were harvested, killed by hypothermia and refrigerated (1°C). Male (n=31) and female (n=26) specimens were separated and measured for total body and abdomen length, 1 (n=10), 3 (n=16), 8 (n=16) and 10 days (n=15) after harvesting. They were weighed, sectioned to separate claws and tails (shell-on), which were weighed individually and their colour parameters (lightness, L*; chromaticity indexes, a* and b*) measured in dorsal and ventral sites. A pooled sample consisting of tail muscle of 2-3 specimens having the same storage times was homogenized and analysed for total lipids, qualitative and quantitative fatty acid composition and malondialdehyde (MDA). The other tails (shell-on) were steamed, the exoskeleton removed and abdominal muscles (shell-off tails) analysed for colour parameters in dorsal and ventral sites, and for free water (by compression method). Data was analysed by GLM using the SAS Package, with sex, storage time and relative interaction (except for data of chemical analysis) as fixed effects. Females and males differed in total (p<0.05) and abdominal (p<0.01) length (8.65 vs 8.27cm and 4.32 vs 4.04cm, respectively) and in body weight (corrected for cheliped weight, due their lack in some cases; 16.35 vs 13.89g; p<0.05), however the cooked-meat yield of shell-on tails was similar (46.53 vs 42.93%; p=0.19). Regarding colour parameters, the two sexes only differed in L*, which was significantly greater in males in the different sites of measurement, except the ventral site of raw shell-on tails. Males and females showed a similar water holding capacity of abdominal meat (mean 10.78±6.33cm2). No differences between the sexes were recorded for total lipids (mean 1.05±0.14%), MDA content and fatty acid profile (means SFA: 22.16%, MUFA: 28.40%, PUFAn6: 20.39%; PUFAn3: 28.80%; EPA: 18.24%; DHA: 7.17%). During refrigerated storage, a significant decrease in water holding capacity of muscle (free water increasing from 14.07 to 26.15cm2 on days 1 and 10, respectively; p<0.001) and in cooked-meat yield (from 50.92 to 39.11% on days 1 and 10, respectively; p<0.01) and sharp changes in cooked tail muscle colour parameters were noticed. The latter body part showed a significant decrease (p<0.001) in a* and b* at the dorsal site and in L* at the ventral site (77.74 and 49.14 on days 1 and 10, respectively) with increasing storage. During the refrigerated storage of the whole crayfish the changes recorded for the examined parameters indicate the quality decay, particularly after the 3rd day.

Welfare and quality of farmed trout fed high plant protein diets. 2 innovative killing method effect on stress and quality indicators

Abstract The fish stunning/slaughtering procedure has an important role both for the ethical aspect related to animal welfare and for the potential quality of the final products. Stressful harvest procedure and killing methods can negatively influence the post mortem biochemical processes with a consequent faster fish freshness loss. In particular, killing procedures causing a long agony are not humane and can shorten fish shelf life; others, more humane, can have risks for the consumers health (anaesthetics or chemical substances) or are not feasible in small/medium size fish industry (spiking and knocking). The aim of this study was to compare the traditional killing method (asphyxia - A) used for rainbow trout (Onchorynchus mykiss) with an innovative stunning/slaughtering method (two-stage electric stun: 2s at a 500Hz electric field of 2.5V/cm and then 58s at a 50Hz electric field of 0.75V/cm - E), through the study of their effects on stress and quality indicators in fish fed with traditional fish meal (FM) or innovative 80% plant protein diet (PV80). Fish (n=30) of each group (FMA, FME, PV80A, PV80E) were stored at 1°C with ice covering and analysed from 0h to 192h from death. The following analyses were done: blood parameters (only at death); rigor index (RI%) and sensorial evaluation with EU Scheme Rule 2406/96 EEC (performed by 5 judge); eye liquor and muscular pH (pHe, pHm); ATP and its degradation products in muscle; lactic acid in muscle and fillet length (FLC) and height contraction % (FHC) (at 0, 3, 6, 24h). Fillet quality appearance was evaluated by absence/presence and size of bloodstains along the midline on the left fillet. Data were analyzed by ANOVA (killing method, diet and their interaction). Asphyxiated fish (A) died within 15-30’ after prolonged struggling and agony, while innovative method stunned/killed fish (E) were immediately stunned and died in 1 minute. Asphyxiated group showed: higher values of blood glucose and muscle lactic acid; lower values of pHe and pHm at 3, 6 and 24h (P<0.01); earlier full rigor (RI 100% at 1h). RI, significantly different (P<0.001) between A and E fish until 6h after death, in E group reached 100% only at 8h. In agreement with this result, FLC of E fish showed lesser contraction both at 3 h (E 6.9 vs A 18.4%, P<0.001) and at 6h (E 13.9 vs A 18.4%, P<0.05). The same emerged for FHC at 3 h (E 0.9 vs 5.3%, P<0.001). The lower values of ATP/IMP ratio at 0, 3 (P<0.001) and 6h (P<0.01) in A fish than in E fish confirmed the stress condition of the first ones. Differences due to the diet were scarce: PV80 fish had higher pHe, pHm and inosine values at 72h (P<0.001). Fish sensorial evaluation indicated A class until 144h in all groups and B class at 192h after death, except in PV80A fish (75% in B class at 144h). As waited, some bloodstains were found in FME (26.7%) and PV80E (53.3%) fillets while A fish had negligible damages (1.7%). The bloodstains should downgraded the fillet acceptance. However, because the portion size trout are traded wholes/gutted by Italian fish industry, the problem seems less serious. The innovative killing procedure, really a fast and humane procedure, need to be improved for fillet appearance.

Physical and organoleptic traits in commercial size bluefin tuna (Thunnus thynnus) reared in floating cage

Abstract The farming of captured wild red tuna (Thunnus thynnus) presents remarkable interest and by now more than one half of tuna caught in the Mediterranean Sea are finished in the fattening cages. The rearing of this species generally does not imply a significant growth of the animals, as instead an improvement of quality and value of the tunas through the restoration of elevated fat levels in flesh, a very appreciated trait by the Japanese consumers. The commercial outlet of the product is the international market, where there is a persistent demand of product for sushi and sashimi. A possibility for increasing the competitiveness of the Italian farmers is to guarantee to the market a very fresh product, characterised by elevated quality and better than the supplies from the other Countries. The aim of the present research was to describe some physical and freshness/organoleptic characteristics of red tuna, particularly the rigor mortis evolution (pre rigor, full rigor and rigor release phases) measured on the whole body. This quality indicator is not easy to measure in tunas due their generally great dimensions and there is a lack of this kind of information in literature, since tunas usually are immediately beheads, eviscerated and deprived of the tail. Specimens of red tunas captured in the Tyrrhenian Sea on October 2005 were transferred to the tuna farm (Vibo Marina, VV) in a circular floating cage, where they were fed with a mixed diet (anchovies, mackerels, sardines, herrings, cephalopods) at the feeding level of 1-4% live weight, depending on the water temperature. In April 2006, a random sample of 10 tunas (44.0±6.2 kg b. w.) was stunned/killed (one by one) using a modified diver gun, shoot by a diver directly in water and then subjected on board to bleeding and spiking and ikejime operations. On each fish, placed in ice covering immediately after bleeding, rigor index, body temperature, eye liquor pH and epaxial and red muscle pH were determined at death, 4h and 24h after death. Sensory evaluation by freshness classes (Rule CE n. 2406/96) and the measurement of rigor index were carried out at the 2nd, 5th, 6th and 7th day after death. The temperature increase with the depth within the tuna body was confirmed at death: eye liquor (21.6±1.6°C), epaxial muscle (21.4±1.3°C) and red muscle close to the vertebral column (30.2±0.9°C). Temperature diminished until 1-2°C within the first 24h in surface and only within 48h in depth. Fish were in Extra class of freshness until 3th day after death and in A class (good quality) until 7th day. Rigor index onset differed, possibly due to the different harvesting time and/or the stress conditions: some tunas, reached the full rigor at 48 hours, others reached rigor at 24h maintaining it until 48 h and the last fish caught showed the shortest full rigor onset (4h) and earlier rigor release (80% at 24h). Rigor release had a moderate decrease (70% at 120h; 54% at 144h and 50% at 168h, excluding the last tuna, which had 7%). The pH of red muscle (6.69 at death) had a fast decrease within 24h (4.99) and an increase at 48h (5.87). This behaviour could be related to a higher speed in the post mortem biochemical processes in red muscle, justified from the still high temperature recorded at 24h. Results confirmed the importance of a rapid and low stressing harvest procedure and fast chilling of red tuna body for high quality product, as already verified by the same authors in a previous trial.

Quality and quality changes during refrigerated storage in diploid and triploid oysters from Orbetello Lagoon (Italy)

Abstract The aim of this study was to evaluate the chemical and nutritional characteristics and quality decay during storage of diploid and triploid Pacific oysters (Crassostrea gigas) reared in Orbetello Lagoon (Grosseto, Italy), a site subject to high variations in environmental parameters. Specimens of diploid (D) and triploid (T) oysters of commercial size and similar age were sampled from an oyster farm (Soc. Coop. GIGAS) in autumn 2005 and in winter, spring and summer 2006. At each sampling date, D (n=60) and T (n=60) oysters were individually weighed, divided into 4 lots, stored under refrigerated conditions (+4°C), and analysed at different times after harvest (1, 3, 7 and 10 days). Oysters were individually weighed again at the different times, measured for maximum length, width and thickness, and opened. The weight of the soft part and shell and the volume of intervalvar liquor were recorded. pH of soft part, gill and mantle colour (CIE L*, a* and b*, Minolta Chromameter) and chemical characteristics (proximate and quantitative fatty acid composition in pooled samples) of soft parts were also analysed. Turbidity of intervalvar liquor was evaluated (by spectrophotometer). A total of 480 specimens (D+T) was studied. For morphological data, the model utilised for the statistical analysis (PROC GLM of SAS Software) included ploidy, season and their interaction as fixed effects; for parameters analysed during storage, the model included ploidy, storage time, season and the interaction between ploidy and storage time. Triploid oysters had greater average (p<0.001) length (102.1 vs 95.7mm), thickness (34.3 vs 28.4mm) and weight (99.3 vs 77.2g) than those diploid. The latter oysters had an inferior market value due to lower economic condition index [thickness/(0.5*(length+width)] (0.38 vs 0.45; p<0.001) and soft part percentage (8.20 vs 12.04%; p<0.001). Differences were also found in chemical characteristics: T showed greater average (p<0.001) dry matter (19.07 vs 14.90%), crude protein (9.47 vs 7.90% w.w.) and total lipid (1.71 vs 0.91%) contents and higher (p<0.01) percentages of C20:5n3 (10.36 vs 8.18%) and PUFAn3 (35.57 vs 28.15%), and lower MUFA (17.72 vs 19.73%; p<0.01) percentage. During storage, T had a higher average weight to length ratio (0.94 vs 0.74; p<0.001), lower weight loss percentage (8.84 vs 10.10%; p<0.05) and higher turbidity of intervalvar liquor (0.754 vs 0.394 absorbance units; p<0.001). T and D differed in colour, T having higher whiteness (L*) and yellowness (b*) of gills and mantle and lower redness (a*) of mantle. Certain parameters reliably reflected changes in oyster quality during storage: percentage weight loss increased significantly from 0% to 12.42% on days 1 and 10, respectively, like pH (days 1-3: 6.19-6.21; day 7: 6.34; day 10: 6.57; p<0.001) while weight/length ratio decreased (from 0.88 to 0.77 on days 1 and 10, respectively; p<0.05). Colour parameters did not change. During storage, trends of parameters were similar in D and T, the interaction between ploidy and storage time never reaching significance. In conclusion, the results confirmed that like D and T oysters from other areas, those from Orbetello Lagoon differ in market and chemical characteristics. The parameters analysed during storage demonstrated the poor average quality of diploid oysters. Further investigations are needed to elucidate the influence of season, which significantly affected almost all the quality parameters analysed, and to highlight the relation between season and quality decay during storage.

Monitoring of fish species in the Lamone river: distribution and morphometric measures of the populations.

Abstract Fish samplings were carried out monthly from spring to autumn during 2008, on the Lamone river and the Campigno stream by an electrofishing, in order to verify the presence of fish populations and the most common species represented. Barb, Barbus plebejus, Blageon, Leuciscus muticellus, Chub, Leuciscus cephalus, South European Nase, Chondrostoma genei were identified. A small population of Brown trout, Salmo trutta fario was also recognized. Barb is the most represented species in all the sites. The samplings highlight that Lamone river presented conditions suitable to fully guarantee the life of the fish populations.