Sensory profiling, liking and gonad composition of sea urchin gonads fed synthetic or natural sources of β-carotene enriched diets

Sea urchin gonads are considered a prized seafood product. Their market price depends on quality and appearance, mainly evaluated through colour. The desirable yellow-orange colour is determined by carotenoids deposition in the gonads, mainly the accumulation of echinenone, which depends on availability, uptake and bioconversion of β-carotene from dietary sources. Two β-carotene sources, a synthetic (SYN) and a natural (paprika, PAP) source, were tested at low (L) and high (H) incorporation target levels (100 and 250 mg β-carotene kg−1 feed) in diets for Paracentrotus lividus. A non-supplemented diet was used as a control (CTRL) diet. After eight weeks of feeding, all diets effectively increased gonad weight and somatic index in both sexes, without significant differences between treatments. Total carotenoid content and profile, lightness (L*) and texture of gonads did not vary significantly among dietary treatments. However, gonad redness (a*) and yellowness (b*) values were significantly higher in urchins fed the L_SYN diet than in those fed either with the CTRL or L_PAP diets; female displayed higher values than male. L_SYN also showed higher consumers´ acceptance when compared to the other diets and female displayed higher acceptance rates than male, probably due to the fact that females were more orange, appealing and pleasant compared with the yellow, grainy and not appealing males. Male fed L_SYN diet exhibited similar colour and carotenoid content compared to wild animals in the same stage of gonad maturation (stage III), but female differed significantly; however, neither of the sex demonstrated acceptance differences in relation to their wild counterparts. Diets with the lower β-carotene inclusion induced changes in gonad colour but not in carotenoid pigments. This suggests that gonad colour is not exclusively modulated by dietary carotenoid supplementation and that it may be affected by other sex-dependent nutritional or metabolic factors.