Special Issue "Recycling and Recovery of Biomass Materials"

A special issue of Recycling (ISSN 2313-4321).

Deadline for manuscript submissions: closed (31 May 2021).

Special Issue Editor

Prof. Dr. Leonel Jorge Ribeiro Nunes
E-Mail Website
Guest Editor
Research Unit on Materials, Energy and Environment for Sustainability, Polytechnic Institute of Viana do Castelo, Rua Escola Industrial e Comercial de Nun’Álvares, 4900-347 Viana do Castelo, Portugal
Interests: sustainability; environmental assessment; rural development; circular economy; radon risk assessment and mitigation
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Special Issue Information

Dear Colleagues,

The growing demand for new forms of energy has led to a significant increase in the use of biomass as a primary source of energy. Although in many situations, the use of biomass is clearly well studied, in other cases, it is a new world, where knowledge is absent about how to best value and recycle these forms of biomass, many of which are classified as waste as a result of production processes. Thermochemical conversion technologies could provide an alternative for the processing of these materials, allowing for a reuse value through the transformation of their properties. The purpose of this Special Issue is to contribute to the increase in knowledge in this area when new forms of biomass appear that are cheaper and more available, but also are potentially more problematic, namely in terms of the effects that can be associated with the use of these new products.

This Special Issue will focus on the recycling and recovery of biomass materials. Several innovative and alternative concepts can be presented, and the topics of energy recovery, circular economy, life cycle assessment, and supply chain could play a major role. Models on various temporal and geographical scales to understand the conditions of technical as well as organizational change are welcome, as are new methods of modeling that can fulfil technical and physical boundary conditions and consider economic environmental and social aspects.

Dr. Leonel Nunes
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Recycling is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Biomass waste recycling
  • Biomass waste recovery
  • Agroindustry byproducts
  • Thermochemical conversion technologies
  • Circular economy

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Published Papers (13 papers)

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Research

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Article
Biocrude Production via Non-Catalytic Supercritical Hydrothermal Liquefaction of Fucus vesiculosus Seaweed Processing Residues
Recycling 2021, 6(3), 45; https://doi.org/10.3390/recycling6030045 - 04 Jul 2021
Viewed by 787
Abstract
The potential of using cold water brown macroalgae Fucus vesiculosus for biocrude production via non-catalytic supercritical hydrothermal liquefaction (HTL) was studied. Demineralization, residue neutralization, and high value-added product (alginate and fucoidan) extraction processes were carried out before using the biomass for HTL biocrude [...] Read more.
The potential of using cold water brown macroalgae Fucus vesiculosus for biocrude production via non-catalytic supercritical hydrothermal liquefaction (HTL) was studied. Demineralization, residue neutralization, and high value-added product (alginate and fucoidan) extraction processes were carried out before using the biomass for HTL biocrude production. Acid leaching was carried out using three demineralization agents: distilled water, dilute citric acid solution, and the diluted acidic aqueous by-product from a continuous HTL pilot facility. Alginate was extracted via H2SO4 and NaCO3 bathing, and fucoidan was extracted using CaCl2. Experimental data show that none of the leaching agents was greatly efficient in removing inorganics, with citric acid leaching with extensive neutralization reaching the highest ash removal efficiency of 47%. The produced 6 sets of biocrudes were characterized by elemental and thermogravimetric analyses. Short (10-min retention) HTL and the extent of leaching residue neutralization were also investigated. Highest biocrude yields were recorded when liquefying non-neutralized citric acid leaching, alginate, and fucoidan extraction residues. On the other hand, thermochemical conversions of short retention time HTL, full neutralization extent, and baseline (dried raw macroalgae) biomass performed worse. Specifically, the highest biocrude yield of 28.2 ± 2.5 wt.% on dry ash-free feedstock basis was recorded when liquefying alginate extraction residues. Moreover, the highest energy recovery of 52.8% was recorded when converting fucoidan extraction residues. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Fungi and Circular Economy: Pleurotus ostreatus Grown on a Substrate with Agricultural Waste of Lavender, and Its Promising Biochemical Profile
Recycling 2021, 6(2), 40; https://doi.org/10.3390/recycling6020040 - 11 Jun 2021
Viewed by 786
Abstract
The increasing production of essential oils has generated a significant amount of vegetal waste that must be discarded, increasing costs for farmers. In this context, fungi, due to their ability to recycle lignocellulosic matter, may be used to turn this waste into new [...] Read more.
The increasing production of essential oils has generated a significant amount of vegetal waste that must be discarded, increasing costs for farmers. In this context, fungi, due to their ability to recycle lignocellulosic matter, may be used to turn this waste into new products, thus generating additional income for essential oil producers. The objectives of our work, within the framework of the European ALCOTRA project FINNOVER, were two-fold. The first was to cultivate Pleurotus ostreatus on solid waste of lavender used for essential oil production. The second was to provide, at the same time, new products that can increase the income of small and medium farms in the Ligurian Italian Riviera. This paper presents two pilot tests in which P. ostreatus was grown on substrates with five different concentrations of lavender waste, ranging from 0 to 100% (w/w). Basidiomata grown on all the substrates and their biochemical profiles were characterized using high-performance liquid chromatography coupled to mass spectrometry. The biochemical analysis of mushrooms proved the presence of molecules with antioxidant and potential pharmacological properties, in particular in mushrooms grown on lavender-enriched substrates. The results open the possibility of producing mushrooms classified as a novel food. Furthermore, the results encourage further experiments aimed at investigating how different substrates positively affect the metabolomics of mushrooms. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Energy Recovery of Agricultural Residues: Incorporation of Vine Pruning in the Production of Biomass Pellets with ENplus® Certification
Recycling 2021, 6(2), 28; https://doi.org/10.3390/recycling6020028 - 22 Apr 2021
Cited by 2 | Viewed by 859
Abstract
The use of residual biomass of forest and/or agricultural origin is an increasingly common issue regarding the incorporation of materials that, until recently, were out of the typical raw material supply chains for the production of biomass pellets, mainly due to the quality [...] Read more.
The use of residual biomass of forest and/or agricultural origin is an increasingly common issue regarding the incorporation of materials that, until recently, were out of the typical raw material supply chains for the production of biomass pellets, mainly due to the quality constraints that some of these materials present. The need to control the quality of biomass-derived fuels led to the development of standards, such as ENplus®, to define the permitted limits for a set of parameters, such as the ash or alkali metal content. In the present study, samples of vine pruning, and ENplus®-certified pellets were collected and characterized, and the results obtained were compared with the limits presented in the standard. The values presented from vine pruning approximated the values presented by Pinus pinaster wood, the main raw material used in the production of certified pellets in Portugal, except for the values of ash, copper (Cu), and nitrogen (N) contents, with vine pruning being out of the qualifying limits for certification. However, it was found that the incorporation of up to 10% of biomass from vine pruning allowed the fulfillment of the requirements presented in the ENplus® standard, indicating a path for the implementation of circular economy processes in the wine industry. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Energy Recovery from Invasive Species: Creation of Value Chains to Promote Control and Eradication
Recycling 2021, 6(1), 21; https://doi.org/10.3390/recycling6010021 - 13 Mar 2021
Cited by 3 | Viewed by 1106
Abstract
The use of biomass as an energy source presents itself as a viable alternative, especially at a time when the mitigation of climate change requires that all possibilities of replacing fossil fuels be used and implemented. The use of residual biomass also appears [...] Read more.
The use of biomass as an energy source presents itself as a viable alternative, especially at a time when the mitigation of climate change requires that all possibilities of replacing fossil fuels be used and implemented. The use of residual biomass also appears as a way to include in the renewable energy production system products that came out of it, while allowing the resolution of environmental problems, such as large volumes available, which are not used, but also by the elimination of fuel load that only contributes to the increased risk of rural fires occurrence. Invasive species contribute to a significant part of this fuel load, and its control and eradication require strong investments, so the valorization of these materials can allow the sustainability of the control and eradication processes. However, the chemical composition of some of these species, namely Acacia dealbata, Acacia melanoxylon, Eucalyptus globulus, Robinia pseudoacacia and Hakea sericea, presents some problems, mainly due to the nitrogen, chlorine and ash contents found, which preclude exclusive use for the production of certified wood pellets. In the case of Eucalyptus globulus, the values obtained in the characterization allow the use in mixtures with Pinus pinaster, but for the other species, this mixture is not possible. From a perspective of local valorization, the use of materials for domestic applications remains a possibility, creating a circular economy process that guarantees the sustainability of operations to control and eradicate invasive species. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Characterization of Used Lubricant Oil in a Latin-American Medium-Size City and Analysis of Options for Its Regeneration
Recycling 2021, 6(1), 10; https://doi.org/10.3390/recycling6010010 - 02 Feb 2021
Cited by 1 | Viewed by 1312
Abstract
Petroleum-derived products, such as lubricant oils, are non-renewable resources that, after use, must be collected and processed properly to avoid negative environmental impacts. A circular economy of used oils requires the re-refining and reuse of the same. Similar to most countries in Latin [...] Read more.
Petroleum-derived products, such as lubricant oils, are non-renewable resources that, after use, must be collected and processed properly to avoid negative environmental impacts. A circular economy of used oils requires the re-refining and reuse of the same. Similar to most countries in Latin America, the management of used oils in Ecuador is still incipient and few cities collect and treat this material properly. In Cuenca, the ETAPA company collects ~1344 t/year of used oils, which are subjected to pretreatment operations prior to their use as fuel in a cement factory. However, combustion generates polluting gases and disallows the adding of value to the used oils. The lack of studies on the characterization and methods utilized for recovering used oils under the conditions found in medium-size Latin-American cities (e.g., Cuenca), alongside a lack of government policies, have hindered the adoption of re-refining operations. The objective of this work is to characterize the used lubricant oils in Cuenca, to compare them with the properties of used oils from other countries, and to suggest some re-refining technologies for oils with similar properties. Used oil samples were collected from mechanic shops and car-lubricating shops for characterization. Its physicochemical properties and metal contents are comparable to the used oils in other countries globally. Specifically, the flash point, kinematic viscosity, TBN, and concentrations of Zn, Cd, and Mg are similar to the properties of used oils in Iraq, Egypt, and the United Arab Emirates. Based on these results, the best re-refining option for used oils in Cuenca is extraction with solvents in which sedimentation and dehydration (already conducted in Cuenca) is followed by a solvent reaction process, a vacuum distillation process, a finishing process with bentonite, and a final filtration step. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Evaluation of the Use of Recycled Vegetable Oil as a Collector Reagent in the Flotation of Copper Sulfide Minerals Using Seawater
Recycling 2021, 6(1), 5; https://doi.org/10.3390/recycling6010005 - 11 Jan 2021
Viewed by 1110
Abstract
Considering sustainable mining, the use of seawater in mineral processing to replace conventional water is an attractive alternative, especially in cases where this resource is limited. However, the use of this aqueous medium generates a series of challenges; specifically, in the seawater flotation [...] Read more.
Considering sustainable mining, the use of seawater in mineral processing to replace conventional water is an attractive alternative, especially in cases where this resource is limited. However, the use of this aqueous medium generates a series of challenges; specifically, in the seawater flotation process, it is necessary to adapt traditional reagents to the aqueous medium or to propose new reagents that achieve better performance and are environmentally friendly. In this research, the technical feasibility of using recycled vegetable oil (RVO) as a collector of copper sulfide minerals in the flotation process using seawater was studied. The study considered the analysis of the metallurgical indexes when different concentrations of collector and foaming reagent were used, considering as collectors the RVO, potassium amyl xanthate (PAX) and mixtures of these, in addition to the methyl isobutyl carbinol (MIBC) as foaming agent. In addition, it was evidenced that the best metallurgical indexes were achieved using 40 g/t of RVO and 15 g/t of MIBC, which corresponded to an enrichment ratio of 6.29, a concentration ratio of 7.01, a copper recovery of 90.06% and a selectivity index with respect to pyrite of 4.03 and with respect to silica of 12.89. Finally, in relation to the study of the RVO and PAX collector mixtures, it was found that a mixture of 60 g/t of RVO and 40 g/t of PAX in the absence of foaming agent presented the best results in terms of copper recovery (98.66%) and the selectivity index with respect to pyrite (2.88) and silica (14.65), improving PAX selectivity and recovery compared to the use of RVO as the only collector. According to these results, it is possible to conclude that the addition of RVO improved the selectivity in the rougher flotation for copper sulfides in seawater. This could be an interesting opportunity for the industry to minimize the costs of the flotation process and generate a lower environmental impact. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Organic Material for Clean Production in the Batik Industry: A Case Study of Natural Batik Semarang, Indonesia
Recycling 2020, 5(4), 28; https://doi.org/10.3390/recycling5040028 - 19 Oct 2020
Cited by 1 | Viewed by 1499
Abstract
Batik has become more desirable in the current fashion mode within the global market, but the environmental damage induced by this fabric’s synthetic dye practices is a matter of concern. This study aimed to discuss the application of organic materials as natural dyes [...] Read more.
Batik has become more desirable in the current fashion mode within the global market, but the environmental damage induced by this fabric’s synthetic dye practices is a matter of concern. This study aimed to discuss the application of organic materials as natural dyes in the clean production of textiles to maintain the environment. The research was a case study from the community services program in Kampung Malon, Gunungpati, Semarang City, Indonesia, focused on the batik home industry of the Zie Batik fabric. Furthermore, natural pigments from various plant organs (stem, leaves, wood, bark, and fruit) of diverse species, including Caesalpinia sappan, Ceriops candolleana, Maclura cochinchinensis, Indigofera tinctorial, I. arrecta, Rhizopora spp., Strobilantes cusia, and Terminalia bellirica were used for this type of material. These pigments are more biodegradable, relatively safe, and easily obtained with zero liquid waste compared to the synthetic variants. The leftover wastewater from the coloring stages was further utilized for other processes. Subsequently, the remaining organic waste from the whole procedure was employed as compost and/or timber for batik production, although a large amount of the wastewater containing sodium carbonate (Na2CO3), alum (KAl(SO4)2·12H2O), and fixatives (Ca(OH)2 and FeSO4) were discharged into the environment during the process of mordanting and fixating, with the requirement of additional treatment. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Communication
On the Production of Potassium Carbonate from Cocoa Pod Husks
Recycling 2020, 5(3), 23; https://doi.org/10.3390/recycling5030023 - 17 Sep 2020
Cited by 3 | Viewed by 1617
Abstract
Cocoa beans are found inside an outer husk; 60% of the cocoa fruit is the outer husk, which is a waste biomass. The husk cannot be used directly as a soil amendment as it promotes the fungal black pod disease, which reduces crop [...] Read more.
Cocoa beans are found inside an outer husk; 60% of the cocoa fruit is the outer husk, which is a waste biomass. The husk cannot be used directly as a soil amendment as it promotes the fungal black pod disease, which reduces crop yield. The pods are segregated from the trees, and their plant nutrient value is wasted. This is particularly true for the small acreage farmers in West Africa. Cocoa pod husk is well suited to be used as a biomass source for electricity production. The waste ash is rich in potassium, which can be converted in various chemical products, most notably, high-purity potassium carbonate. This study reviews the information known about cocoa and cocoa pod husk, and considers the socio-economic implications of creating a local economy based on collecting the cocoa pod husk for electricity production, coupled with the processing of the waste ash into various products. The study demonstrates that the concept is feasible, and also identifies the local conditions required to create this sustainable economic process. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
Article
Exploring Biogas and Biofertilizer Production from Abattoir Wastes in Nigeria Using a Multi-Criteria Assessment Approach
Recycling 2020, 5(3), 18; https://doi.org/10.3390/recycling5030018 - 19 Aug 2020
Cited by 1 | Viewed by 1831
Abstract
Management of waste streams from abattoirs is a major challenge in developing countries. Harnessing these wastes as resources for the production of biogas and biofertilizer could contribute to curbing the environmental menace and to addressing the problems of energy and food deficits in [...] Read more.
Management of waste streams from abattoirs is a major challenge in developing countries. Harnessing these wastes as resources for the production of biogas and biofertilizer could contribute to curbing the environmental menace and to addressing the problems of energy and food deficits in Nigeria. However, large scale uptake of the technology is faced with techno-socio-economic and the lack of data required for effective investment decisions. In this study, the potential use of waste generated in the north central region of Nigerian abattoirs, representing approximately 12% of the land and 6% of the population, were evaluated for suitability for biogas and biofertilizer production. Data acquired from the study sites were used for computational estimation and integrated into strengths, weaknesses, opportunities, and threats (SWOT) analysis to give a detailed overview of the prospects and the limiting factors. The study revealed that high investment costs and public subsidies for fossil fuels are the key limiting factors while the prospects of tapping into the unexploited carbon markets and multiple socio-economic and environmental benefits favors investment. Public supports in the form of national policy reforms leading to intervention programs are required for progress. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Utilization of Waste Cooking Oil via Recycling as Biofuel for Diesel Engines
Recycling 2020, 5(2), 13; https://doi.org/10.3390/recycling5020013 - 08 Jun 2020
Viewed by 1904
Abstract
In this study, waste cooking oil (WCO) was used to successfully manufacture catalyst cracking biodiesel in the laboratory. This study aims to evaluate and compare the influence of waste cooking oil synthetic diesel (WCOSD) with that of commercial diesel (CD) fuel on an [...] Read more.
In this study, waste cooking oil (WCO) was used to successfully manufacture catalyst cracking biodiesel in the laboratory. This study aims to evaluate and compare the influence of waste cooking oil synthetic diesel (WCOSD) with that of commercial diesel (CD) fuel on an engine’s operating characteristics. The second goal of this study is to compare the engine performance and temperature characteristics of cooling water and lubricant oil under various engine operating conditions of a test engine fueled by waste cooking oil and CD. The results indicated that the engine torque of the engine running with WCOSD dropped from 1.9 Nm to 5.4 Nm at all speeds, and its brake specific fuel consumption (BSFC) dropped at almost every speed. Thus, the thermal brake efficiency (BTE) of the engine fueled by WCOSD was higher at all engine speeds. Also, the engine torque of the WCOSD-fueled engine was lower than the engine torque of the CD-fueled engine at all engine speeds. The engine’s power dropped sequentially through 0.3 kW, 0.4 kW, 0.6 kW, 0.9 kW, 0.8 kW, 0.9 kW, 1.0 kW and 1.9 kW. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Thermochemical Conversion of Olive Oil Industry Waste: Circular Economy through Energy Recovery
Recycling 2020, 5(2), 12; https://doi.org/10.3390/recycling5020012 - 01 Jun 2020
Cited by 5 | Viewed by 2404
Abstract
The demand for new sources of energy is one of the main quests for humans. At the same time, there is a growing need to eliminate or recover a set of industrial or agroforestry waste sources. In this context, several options may be [...] Read more.
The demand for new sources of energy is one of the main quests for humans. At the same time, there is a growing need to eliminate or recover a set of industrial or agroforestry waste sources. In this context, several options may be of interest, especially given the amounts produced and environmental impacts caused. Olive pomace can be considered one of these options. Portugal, as one of the most prominent producers of olive oil, therefore, also faces the problem of dealing with the waste of the olive oil industry. Olive pomace energy recovery is a subject referenced in many different studies and reports since long ago. However, traditional forms of recovery, such as direct combustion, did not prove to be the best solution, mainly due to its fuel properties and other characteristics, which cause difficulties in its storage and transportation as well. Torrefaction and pyrolysis can contribute to a volume reduction, optimizing storage and transportation. In this preliminary study, were carried out torrefaction and pyrolysis tests on olive pomace samples, processed at 300 °C, 400 °C, and 500 °C, followed by laboratory characterization of the materials. It was verified an improvement in the energy content of the materials, demonstrating that there is potential for the use of these thermochemical conversion technologies for the energy recovery of olive pomace. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Review

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Review
Biodegradation of Hemicellulose-Cellulose-Starch-Based Bioplastics and Microbial Polyesters
Recycling 2021, 6(1), 22; https://doi.org/10.3390/recycling6010022 - 22 Mar 2021
Cited by 5 | Viewed by 1424
Abstract
The volume of discarded solid wastes, especially plastic, which accumulates in large quantities in different environments, has substantially increased. Population growth and the consumption pattern of societies associated with unsustainable production routes have caused the pollution level to increase. Therefore, the development of [...] Read more.
The volume of discarded solid wastes, especially plastic, which accumulates in large quantities in different environments, has substantially increased. Population growth and the consumption pattern of societies associated with unsustainable production routes have caused the pollution level to increase. Therefore, the development of materials that help mitigate the impacts of plastics is fundamental. However, bioplastics can result in a misunderstanding about their properties and environmental impacts, as well as incorrect management of their final disposition, from misidentifications and classifications. This chapter addresses the aspects and factors surrounding the biodegradation of bioplastics from natural (plant biomass (starch, lignin, cellulose, hemicellulose, and starch) and bacterial polyester polymers. Therefore, the biodegradation of bioplastics is a factor that must be studied, because due to the increase in the production of different bioplastics, they may present differences in the decomposition rates. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Review
Prospects of Red King Crab Hepatopancreas Processing: Fundamental and Applied Biochemistry
Recycling 2021, 6(1), 3; https://doi.org/10.3390/recycling6010003 - 02 Jan 2021
Cited by 2 | Viewed by 1409
Abstract
Since the early 1980s, a large number of studies on enzymes from the red king crab hepatopancreas were conducted. They have been relevant both from a fundamental point of view in terms of studying the enzymes of marine organisms and in terms of [...] Read more.
Since the early 1980s, a large number of studies on enzymes from the red king crab hepatopancreas were conducted. They have been relevant both from a fundamental point of view in terms of studying the enzymes of marine organisms and in terms of rational natural resource management aimed to obtain new valuable products from the processing of crab fishing waste. Most of these works were performed by Russian scientists due to the area and amount of waste of red king crab processing in Russia (or the Soviet Union). However, the close phylogenetic kinship and the similar ecological niches of commercial crab species and the production scale of the catch provide the bases for the successful transfer of experience in the processing of the red king crab hepatopancreas to other commercial crab species caught worldwide. This review describes the value of recycled commercial crab species, discusses processing problems, and suggests possible solutions for these issues. The main emphasis is made on hepatopancreatic enzymes as the most salubrious products of red king crab waste processing. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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