Abstract
Commonly known as “purple sea urchin,” Paracentrotus lividus occurs in the Mediterranean Sea and the eastern Atlantic Ocean. This species is a highly appreciated food resource and Italy is the main consumer among the European countries. Gonads are the edible part of the animal but they represent only a small fraction (10–30%) of the entire sea urchin mass, therefore, the majority ends up as waste. Recently, an innovative methodology was successfully developed to obtain high-value collagen from sea urchin by-products to be used for tissue engineering. However, tissues used for the collagen extraction are still a small portion of the sea urchin waste (<20%) and the remaining part, mainly the carbonate-rich test and spines, are discarded. Residual cell tissues, tests, and spines contain polyunsaturated fatty acids, carotenoids, and a class of small polyphenols, called polyhydroxynaphthoquinones (PHNQ). PHNQ, due to their polyhydroxylated quinonoid nature, show remarkable pharmacologic effects, and have high economic significance and widespread application in several cosmetic and pharmaceuticals applications. A green extraction strategy aimed to obtain compounds of interest from the wastes of sea urchins was developed. The core strategy was the supercritical CO2 technique, characterized by low environmental impacts. Fatty acids and carotenoids were successfully and selectively extracted and identified depending on the physical parameters of the supercritical CO2 extraction. Finally, the exhausted powder was extracted by solvent-based procedures to yield PHNQ. The presence of Spinochrome A and Spinochrome B was confirmed and extracts were characterized by a remarkably high antioxidant activity, measured through the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. Overall, the selective and successive extraction methods were validated for the valorization of waste from sea urchins, demonstrating the feasibility of the techniques targeting added-value compounds.
Highlights
Food waste valorization implies its conversion into higher-value products that contribute back to the supply chain or other kinds of applications that support the circular economy approach where useful materials, once seen as waste or by-products, are recycled
ABTS radical cation was produced by reacting ABTS aqueous solution with 2.45 mM ammonium persulfate and allowing the mixture to stand in the dark at room temperature for 12–16 h before use
Pure Supercritical CO2 Figure 1A displays the kinetics of extraction when the supercritical CO2 extraction was run on the pristine sea urchin powder
Summary
Food waste valorization implies its conversion into higher-value products that contribute back to the supply chain or other kinds of applications that support the circular economy approach where useful materials, once seen as waste or by-products, are recycled. Given the high interest in the environmental issues, already remarked by the 17 Sustainable and Development Goals of Agenda 2030, where sustainability is the core, nowadays a lot of research is ongoing in the field of food industrial sustainability during the production process and at the end of the chain [1]. The shift from a linear economy model to a circular one differs substantially in the perspective on sustainability, aiming to ensure healthy and safe living while causing less harm to the environment Within this context, sea urchins, belonging to the class Echinoidea of the echinoderm phylum, are a highly appreciated food resource. The tissues used for the collagen extraction are a small portion of sea urchin waste (
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