Elsevier

Journal of Cleaner Production

Volume 374, 10 November 2022, 134052
Journal of Cleaner Production

Comprehensive biorefinery of invasive European green crab (Carcinus maenas) into multiple high-value biomolecules

https://doi.org/10.1016/j.jclepro.2022.134052Get rights and content

Highlights

  • Invasive European green crab was biorefined into multiple biomolecules.

  • The single process involved the use of enzymes (trypsin, papain).

  • Crab oil, minerals, carotenoprotein & chitin were recovered.

  • The composition and properties of the biomolecules suggests wide applications.

Abstract

European green crab (Carcinus maenas) is an invasive species globally and is considered marine waste that needs to be eliminated. In this study, the green crab was biorefined via a clean enzymes-assisted bioprocess into multiple value-added bioproducts, i.e., crab oil, minerals, carotenoprotein, and chitin. The recovered crab oil was rich in unsaturated fatty acids such as EPA and DHA as per GC-MS analysis. Citric acid, as a replacement for conventional hash acids, was found to optimally demineralize the crab powder at 1 M and 4 °C for 18 h, where the recovered crab minerals identified using ICP-MS showed a high level of calcium, in form of nutritious calcium citrate. Crab carotenoprotein recovered using trypsin exhibited antioxidant properties. It contained 139.26 μg/g of carotenoids pigment, mainly astaxanthin and astaxanthin diester, as verified by thin layer chromatography, and the protein component in the carotenoprotein was rich in essential amino acids such as leucine via UPLC-MS. The produced crab chitin from papain-assisted deproteinization showed characteristic physicochemical properties following FTIR and XRD analysis. These biomolecules biorefined from the green crab possess wide applications in food, pharmaceutical, biomaterials, etc. This new biorefinery strategy enhances the sustainability for biowaste utilization.

Introduction

European green crab (Carcinus maenas) is one of the top 100 most unwanted invasive species in the world (Baillie and Grabowski, 2019). This green crab is small in size, reproduces and grows rapidly, and is very resilient to a wide range of environmental conditions. It is currently distributed widely along the coasts in North America and Australia, after being introduced in the 1800s and 1900s, and more recently in South Africa, South America, and East Asia (Ens et al., 2022), probably transported via the hulls of merchant ships. It out-competes other shellfish and fish species that serve as natural food sources to present a serious threat to the marine ecosystem and fishery industry. However, there is currently no concrete management strategy being able to extirpate this green crab once they invade. In Canada, fishers are permitted by Fisheries and Oceans Canada to destroy the green crabs they accidentally harvest with their catch, to allow the native species to re-emerge. In this context, it is worthwhile to explore the utilization of the European green crab, which is seldomly studied.

On the other hand, the European green crab is potentially an excellent source of essential nutrients (proteins, lipids, and minerals) and other valuable compounds (chitin, carotenoid pigments, etc.). Crustacean waste has a beneficial lipid profile with high content of essential fatty acids (i.e., omega-3 oils), chitin, carotenoproteins (carotenoid and protein complex), essential amino acids, calcium, and other minerals (Wade et al., 2017), etc. These biological compounds can be further utilized in several fields like agriculture, biomedicine, food & feed, pharmaceuticals, cosmetics, and biofuels. Although there are several compounds (protein, chitin, pigments, lipids, minerals) present in crustacean waste, very little research have reported a single biorefinery process able to completely recover all the compounds from the waste. This is probably due to the natural complex states of the compounds in the crustacean waste, hindering the development of efficient bioconversion approaches to fractionate and isolate each of them. For example, chitin is mainly present in a highly mineralized chitinous protein matrix in the shells, and the essential antioxidant pigment astaxanthin is usually conjugated with proteins, or esterified with saturated or unsaturated fatty acids (Moussian, 2019). The conventional methods to recover these compounds from crustacean waste are tedious and involve extensive use of harsh chemicals, which are hazardous to humans and the environment. For instance, strong inorganic acids such as HCl are traditionally used for demineralization while NaOH is applied for deproteination. A recent study reported a one-step biorefinery of astaxanthin-rich oil, protein, chitin, and chitosan from shrimp waste, in which supercritical fluid extraction (SFE) was applied with a combination of mechanical pressing, to extract the compounds (Aneesh et al., 2020). Such physical approaches, including SFE, pressure dielectric barrier discharge (Borić et al., 2020), or ionic liquids (Tolesa et al., 2019), require sophisticated and expensive equipment. Another study developed an enzymatic conversion of protein, chitin, and astaxanthin from shrimp waste, where two types of proteases were used to obtain protein hydrolysates; the residues were treated with chitinase to obtain chitin oligomers, while astaxanthin was extracted using ethyl acetate, leaving only the minerals (Deng et al., 2020). The use of enzymes in biorefinery is efficient, eco-friendly, mild, and easy to control. Various hydrolytic agents such as proteases have been used to extract carotenoprotein, and deproteinize the crustacean shells to aid chitin extraction from crustacean shells (Cahyaningtyas et al., 2022; Hamdi et al., 2017). Thus, we hypothesized that a comprehensive clean biorefinery process that avoids using harsh reagents but involves the assistance of enzymes could be designed. This study is novel and transforms the abundant but underutilized crab resource into multiple value-added bioproducts and provides a win-win method for clean production of biomolecules and post-invasion management of the invasive crab.

The reported study was aimed to fill the gap between the need for green crab management and previous research that focused on component analyses and unsustainable extraction of components from the generated waste. In order to obtain value-added biomolecules including crab oil, minerals, carotenoprotein, and chitin via a single clean biorefinery, a few objectives, e.g., to optimize demineralization using citric acid to recover carotenoprotein using trypsin-assisted hydrolysis and to recover chitin via a papain-assisted deproteinization were studied. The developed biorefinery process maximized the value of the European green crab to accrue potential benefits for the circular economy and environmental health protection.

Section snippets

Chemicals

Citric acid, ethylenediaminetetraacetic acid (EDTA), ferric chloride (FeCl3), ferrous sulfate (FeSO4), papain, sodium chloride (NaCl), sodium hypochlorite (NaOCl), and sodium phosphate were purchased from Fisher Scientific (Geel, Belgium). Acetone, acetonitrile, anhydrous sodium sulfate, 2,2-dipheyl-1-picrylhydrazyl (DPPH), ethanol, NHI–C FAME Mix, ferric chloride, ferrous sulfate, Folin's phenol reagent, hexane, hydrochloric acid (HCl), hydrogen peroxide (H2O2), methanol (MeOH), petroleum

Proximate composition of green crab powder

The European green crab (C. maenas) powder contained protein of 20.98 ± 0.39%, fat of 3.00 ± 0.09%, chitin of 11.26 ± 3.83%, and ash of 38.05 ± 2.14% on dry weight bases. The results suggested that the abundantly available but underutilized green crab was a good source of useful biomolecules such as proteins and chitin. The protein content in green crab in this study was consistent with previously reported protein values of 6.2–18.4% in whole green crab, regardless of the crab size and month

Conclusion

The European green crab as waste was bio-transformed into valuable oil, minerals, proteins, carotenoprotein, and chitin, through the one enzyme-based green biorefinery strategy designed in this study. These bioproducts recovered from the crab were characterized by composition, bioactivity, and physiochemical properties, and potentially have wide applications in foods, feeds, biomedicine, and material industries.

CRediT authorship contribution statement

Yi Zhang: Conceptualization, Methodology, Investigation, Visualization, Writing – original draft, Writing – review & editing. Paola Sully: Investigation, Writing – original draft, Data curation, Formal analysis, Software. Lea Spitzer: Visualization, Formal analysis, Writing – original draft. Pierre Dutilleul: Methodology, Formal analysis, Writing – review & editing. Benjamin K. Simpson: Conceptualization, Methodology, Resources, Writing – original draft, Writing – review & editing, Funding

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Program.

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