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Add To Calendar 06/10/2021 15:10:0006/10/2021 15:30:00Europe/LisbonAquaculture Europe 2021INCLUSION OF Dunaliella salina IN COLD EXTRUDED DIETS RESULTS IN SEA URCHIN GONADS WITH HIGH CONSUMER ACCEPTANCESidney-HotelThe European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982

INCLUSION OF Dunaliella salina IN COLD EXTRUDED DIETS RESULTS IN SEA URCHIN GONADS WITH HIGH CONSUMER ACCEPTANCE

Inês Garridoa,b *, Tiago Sáb, Luís F. Baiãoa,b,c, Helena M. Amaroa, Tânia Tavarese, F. Xavier Malcatae,f, Isabel Costad, A. Catarina Guedesa,d, Luísa M.P. Valentea,b

aCIIMAR/CIIMAR, Interdisciplinary Centre of Marine and Environment Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, S/N, 4450-208 Matosinhos, Portugal

bICBAS, School of Medicine and Biomedical Sciences, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal

cSense Test, Rua Zeferino Costa, 341, 4400-345 Vila Nova de Gaia, Portugal

dISS, Ínclita Seaweed Solutions, CIIMAR – Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, S/N, 4450-208 Matosinhos, Portugal

eLEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

fFEUP – Faculty of Engineering of University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

E-mail: garridoines44@gmail.com

 



Introduction

Sea urchin gonads have been increasingly demanded and marketed in Asian countries and Europe mainly due to its organoleptic features. Paracentrotus lividus is the most abundant species in southern Europe. To avoid an overexploitation of wild stocks echinoculture has become a sustainable solution. Baião et al. (2019) reported high gonad yield by using a formulated extruded diet for P. lividus, but resulted in gonads with a pale-yellow colour. Colour is the first stimuli presented to a consumer and a major marketability influencing factor; consumers prefer yellow-orange colour gonads. Echinenone is the most abundant carotenoid in the gonads and depends on availability, uptake and bioconversion of β-carotene from dietary sources (Symonds et al. 2007). The present study aimed to investigate the effectiveness of a natural source of β-carotene in producing P. lividus gonads with acceptable colour.

Materials and methods

A control diet (CTRL) was formulated and compared to four isonitrogeneous and isoenergetic experimental diets containing two levels of Dunaliella salina (0.75% or 1.5%, in diets D1 and D2, respectively) as a natural rich source of β-carotene. In two of these Dunaliella supplemented diets, a commercially available macroalgae mix was totally replaced by Porphyra (D1P and D2P). Another diet was included by supplementing the CTRL diet with 1.2% of crystal glycine (GLY). All diets were cold extruded (<30 °C) and softly dried (<45ºC); diets were distributed every 48h, during 8 weeks, to quadruplicate groups of sea urchins, placed in plastic mesh cages in a saltwater recirculation aquaculture system (RAS) with a stocking density of 3.5 kg.m-2, temperature 18 ºC, salinity 35‰, and a 10h L/14h D photoperiod. At the end of the trial all sea urchins were individually weighted and measured. Gonads of 8 animals per tank were sampled for chemical composition, carotenoid characterisation by high performance liquid chromatography (HPLC), and evaluation of colour by lightness, redness, yellowness, hue angle and chroma (L*, a*, b*, C* and h* respectively) and texture.

Results

All diets were well accepted by the sea urchins, resulting in a similar SGR (0.1) among treatments. Diets were able to enhance gonad yield, that increased from 6.4 and 8.9 to 15.8 and 17.0, in males and females, respectively. Gonad yield and gonadal somatic index (GSI) were similar among diets, but varied significantly between sexes; females had higher yield and GSI than males. Final gonad composition presented significant differences between sexes and diets. Females had higher dry matter and energy, but lower protein content than males. Sea urchins fed diet D1 resulted in the highest gonadal protein content, whilst diet D2 presented the highest energy, irrespectively of the sex. Diets have significantly affected all free amino acids; urchins fed with the experimental diets presented significantly higher concentrations of arginine, valine, methionine and glycine in gonads than the urchins fed with the CTRL diet.

The content of carotenoids in gonads did not vary significantly among dietary treatments, but significant differences were observed between sexes: males containing higher concentrations of total carotenoids, echinenone (most abundant pigment: 12.4 – 17.5 µg.g-1 WW), α-carotene and β-carotene than females, but practically undetected lutein and zeaxantin. Female’s most abundant pigments were lutein (3.7 – 5.3 µg.g-1 WW) and echinenone (3.3. – 5.9 µg.g-1 WW), followed by zeaxantin (1.9 – 3.2 µg.g-1 WW). Gonad colour presented significant differences between sexes and diets. Gonads of males had higher L* and h*, but lower a*, b* and C* values than females. Sea urchins fed Dunaliella-diets produced gonads with lower L* and h* values, and higher a* value compared to those fed with CTRL diet. Sea urchins fed with diet D2 had firmer gonads than those fed diet D1P, but did not differ from the CTRL. L* was positively related with echinenone (0.7) and a* and b* positively correlated with lutein (0.8) and zeaxantin (0.8).

Conclusions

All tested diets were able to enhance gonad yield, with females having larger gonads than males, but without differences between diets. All Dunaliella-diets were able to produce redder and less luminous gonads than the CTRL diet. This indicates an improvement in gonad colour since consumers prefer gonads with lower values of L* and higher values of a* (Baião et al. 2020). Overall, diets supplemented with Dunaliella were able to improve the colour of sea urchin gonads in relation to the CTRL group, resulting in medium to bright orange/red gonads with high acceptance for consumers.

Acknowledgments

Work supported by Project CAVIAR - Market valorisation of sea urchin gonads through dietary modulation (FA_05_2017_015), financed through programme Fundo Azul.

References

Baião, L.F., Rocha, C., Lima, R.C., Marques, A., Valente, L.M.P., Cunha, L.M., 2020. Sensory profiling, liking and acceptance of sea urchin gonads from the North Atlantic coast of Portugal, aiming future aquaculture applications. Food Research International.

Baião, L.F., Rocha, F., Costa, M., Sá, T., Oliveira, A., Maia, M.R.G., Fonseca, A.J.M., Pintado, M., Valente, L.M.P., 2019. Effect of protein and lipid levels in diets for adult sea urchin Paracentrotus lividus (Lamarck, 1816). Aquaculture. 506, 127-138.

Symonds, R.C., Kelly, M.S., Caris-Veyrat, C., Young, A.J., 2007. Carotenoids in the sea urchin Paracentrotus lividus: Occurrence of 9′-cis-echinenone as the dominant carotenoid in gonad colour determination. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 148, 432-444.