Compositional and nutritional insights into Mediterranean sea cucumbers: A study on Holothuria polii and Holothuria tubulosa from Southern Italy

Sea cucumbers are marine invertebrates with important ecological roles and a food delicacy with high market value. This study investigated the compositional profile and nutritional features of two Mediterranean sea cucumbers, Holothuria polii and Holothuria tubulosa, harvested in Adriatic Sea and Ionian Sea, Southern Italy. The macronutrients were determined by AOAC methods. The minerals were determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and fatty acids by Gas Chromatography-Mass Spectrometry/ Flame Ionization Detector (GC-MS/FID). Total mercury content was analyzed by Thermal Decomposition-Amalgamation-Atomic Absorption Spectrophotometry. Results showed that holothurians from the two basins are good protein (average 38-60 % dry mass) and mineral (32-37 % dry mass) sources, have a very low lipid content (1-3.7 % dry mass) and negligible mercury levels (0.016-0.038 mg kg-1 dry mass). H. polii showed a higher nutrient density, especially regarding minerals, with calcium, sodium and magnesium as the major ones. The analysis of fatty acid profiles enabled the identification of specific markers, reflecting habitat characteristics, seasonality, and dietary attitudes of holothurians. High percentages of arachidonic acid (47-65 % of total polyunsaturated fatty acids) and remarkable levels of branched-chain (6-9 % of total fatty acids) and odd-chain saturated fatty acids (1.7-3.8 % of total fatty acids), trophic markers of benthic food webs and sediment microbiota, were characterizing traits. Principal Component Analysis showed a neat discrimination of holothurians based on the species and harvesting site. Results underscore the nutritional properties of Mediterranean holothurian as part of a balanced diet, highlighting their potentialities as sources of molecules of nutritional and nutraceutical interest.