Protein recovery by ultrafiltration during isolation of chitin from shrimp shells Parapenaeus longirostris

Valorization of fishery industry waste: Chitosan extraction and its application in the industry

Waste from the fishing industry is disposed of in soils and oceans, causing environmental damage. However, it is also a source of valuable compounds such as chitin. Although chitin is the second most abundant polymer in nature, its use in industry is limited due to the lack of standardized and scalable extraction methods and its poor solubility. The deacetylation process increases its potential applications by enabling the recovery of chitosan, which is soluble in dilute acidic solutions. Chitosan is a polymer of great importance due to its biocompatible and bioactive properties, which include antimicrobial and antioxidant capabilities. Chitin extraction and its deacetylation to obtain chitosan are typically performed using chemical processes that involve large amounts of strongly acidic and alkaline solutions. To reduce the environmental impact of this process, extraction methods based on biotechnological tools, such as fermentation and chitin deacetylase, as well as emerging technologies, have been proposed. These extraction methods have demonstrated the potential to reduce or even avoid using strong solvents and shorten extraction time, thereby reducing costs. Nevertheless, it is important to address existing gaps in this area, such as the requirements for large-scale implementation and the determination of the stoichiometric ratios for each process. This review highlights the use of biotechnological tools and emerging technologies for chitin extraction and chitosan production. These approaches truly minimize environmental impact, reduce the use of strong solvents, and shorten extraction time. They are a reliable alternative to fishery waste valorization, lowering costs; however, addressing the critical gaps for their large-scale implementation remains challenging.

Chitin and Its Derivative Chitosan: Distribution in Nature, Applications, and Technology Research (A Review)

The present review highlights the chitin/chitosan as biopolymers that are promising for biomedical research development. Our goal was to assess the potential for practical use of these biopolymers and to summarize information on traditional and innovative technologies for their production and purification. The widespread occurrence of chitin and chitosan in nature as well as the unique chemical and biological properties of chitosan are reasons of growing interest in the use of the latter in several pharmaceutical fields. The main stages of chitin extraction and its further modification into chitosan are deproteinization, demineralization, deacetylation, and the main methods of chitosan purification are filtration, dialysis and reprecipitation. The profitability of the production of chitin/chitosan from crustaceans and edible mushrooms is approximately at the same level. The cost of mushroom products can be reduced by using agricultural or forestry waste as nutrient substrates. This makes the use of fungi as sources of chitin/chitosan in forested regions a rather promising issue.

Recovery of Nutrients from Cod Processing Waters

Liquid side-streams from food industries can be processed and used in food applications and contribute to reduce the environmental footprint of industries. The goal of this study was to evaluate the effectiveness and applicability of protein and phosphorus separation processes, namely microfiltration, ultrafiltration and flocculation, using protein-rich process waters with low (LS) and high (HS) salt content from the processing of salted cod (Gadus morhua). The application of different flocculants (chitosan lactate and Levasil RD442) were evaluated at different concentrations and maturation periods (0, 1 or 3 h). The results showed that different flocculation treatments resulted in different recoveries of the nutrients from LS and HS. Proteins in LS could be most efficiently recovered by using Levasil RD442 0.25% and no maturation period (51.4%), while phosphorus was most efficiently recovered when using Levasil RD442 1.23% and a maturation period of 1 h (34.7%). For HS, most of its protein was recovered using Levasil RD442 1.23% and a maturation period of 1 h (51.8%), while phosphorus was recovered the most using Levasil 1.23% and no maturation period (47.1%). The salt contents allowed interactions through intermolecular forces with Levasil RD442. The ultrafiltration method was effective on HS since it recovered higher percentages of nutrients in the retentate phase (57% of the protein and 46% of the phosphorus) compared to LS.

3D Printing Approach to Valorization of Agri-Food Processing Waste Streams

With increasing evidence of their relevance to resource recovery, waste utilization, zero waste, a circular economy, and sustainability, food-processing waste streams are being viewed as an aspect of both research and commercial interest. Accordingly, different approaches have evolved for their management and utilization. With excellent levels of customization, three-dimensional (3D) printing has found numerous applications in various sectors. The focus of this review article is to explain the state of the art, innovative interventions, and promising features of 3D printing technology for the valorization of agri-food processing waste streams. Based on recent works, this article covers two aspects: the conversion of processing waste streams into edible novel foods or inedible biodegradable materials for food packing and allied applications. However, this application domain cannot be limited to only what is already established, as there are ample prospects for several other application fields intertwining 3D food printing and waste processing. In addition, this article presents the key merits of the technology and emphasizes research needs and directions for future work on this disruptive technology, specific to food-printing applications.

Functional proteins through green refining of seafood side streams

Scarcity of nutritive protein is a major global problem, the severity of which is bound to increase with the rising population. The situation demands finding additional sources of proteins that can be both safe as well as acceptable to the consumer. Food waste, particularly from seafood is a plausible feedstock of proteins in this respect. Fishing operations result in appreciable amounts of bycatch having poor food value. In addition, commercial processing results in 50 to 60% of seafood as discards, which consist of shell, head, fileting frames, bones, viscera, fin, skin, roe, and others. Furthermore, voluminous amounts of protein-rich effluents are released during commercial seafood processing. While meat from the bycatch can be raw material for proteinous edible products, proteins from the process discards and effluents can be recovered through biorefining employing upcoming, environmental-friendly, low-cost green processes. Microbial or enzyme treatments release proteins bound to the seafood matrices. Physico-chemical processes such as ultrasound, pulse electric field, high hydrostatic pressure, green solvent extractions and others are available to recover proteins from the by-products. Cultivation of photosynthetic microalgae in nutrient media consisting of seafood side streams generates algal cell mass, a rich source of functional proteins. A zero-waste marine bio-refinery approach can help almost total recovery of proteins and other ingredients from the seafood side streams. The recovered proteins can have high nutritive value and valuable applications as nutraceuticals and food additives.

Hemoglobin-mediated lipid oxidation of herring filleting co-products during ensilaging and its inhibition by pre-incubation in antioxidant solutions

The aims of this study were to investigate the role of hemoglobin (Hb) in lipid oxidation development during ensilaging of herring filleting co-products, and, to inhibit this reaction by pre-incubating the co-products in water or physiological salt, with/without different antioxidants. Results showed that both peroxide value (PV) and 2-thiobarbituric acid reactive substances (TBARS) gradually increased during 7 days of ensilaging at 22 °C in absence of antioxidants. The increase in TBARS was proportional to the Hb levels present, while PV was less affected. A Hb-fortified Tris-buffer model system adjusted to pH 3.50 confirmed that Hb changed immediately from its native oxyHb to the metHb state, which facilitated heme group release and thus probably explains the increased PV and TBARS during ensilaging. Pre-incubating the co-products for 30 s in a solution containing 0.5% rosemary extract was the most promising strategy to inhibit lipid oxidation both in the co-products during pre-processing storage and during the actual ensilaging. The solution could be re-used up to ten times without losing its activity, illustrating that this methodology can be a scalable and cost-effective strategy to extend the oxidative stability of herring co-products allowing for further value adding e.g., into a high-quality silage.

Sustainable Agriculture Systems in Vegetable Production Using Chitin and Chitosan as Plant Biostimulants

Chitin and chitosan are natural compounds that are biodegradable and nontoxic and have gained noticeable attention due to their effective contribution to increased yield and agro-environmental sustainability. Several effects have been reported for chitosan application in plants. Particularly, it can be used in plant defense systems against biological and environmental stress conditions and as a plant growth promoter—it can increase stomatal conductance and reduce transpiration or be applied as a coating material in seeds. Moreover, it can be effective in promoting chitinolytic microorganisms and prolonging storage life through post-harvest treatments, or benefit nutrient delivery to plants since it may prevent leaching and improve slow release of nutrients in fertilizers. Finally, it can remediate polluted soils through the removal of cationic and anionic heavy metals and the improvement of soil properties. On the other hand, chitin also has many beneficial effects such as plant growth promotion, improved plant nutrition and ability to modulate and improve plants’ resistance to abiotic and biotic stressors. The present review presents a literature overview regarding the effects of chitin, chitosan and derivatives on horticultural crops, highlighting their important role in modern sustainable crop production; the main limitations as well as the future prospects of applications of this particular biostimulant category are also presented.

Sustainable and eco-friendly strategies for shrimp shell valorization

Among the seafood used globally, shellfish consumption is in great demand. The utilization of these shellfish such as prawn/shrimp has opened a new market for the utilization of the shellfish wastes. Considering the trends on the production of wealth from wastes, shrimp shell wastes seem an important resource for the generation of high value products when processed on the principles of a biorefinery. In recent years, various chemical strategies have been tried to valorize the shrimp shell wastes, which required harsh chemicals such as HCl and NaOH for demineralization (DM) and deproteination (DP) of the shrimp wastes. Disposal of chemicals by the chitin and chitosan industries into the aquatic bodies pose harm to the aquatic flora and fauna. Thus, there has been intensive efforts to develop safe and sustainable technologies for the management of shrimp shell wastes. This review provides an insight about environmentally-friendly methods along with biological methods to valorize the shrimp waste compared to the strategies employing concentrated chemicals. The main objective of this review article is to explain the utilization shrimp shell wastes in a productive manner such that it would be offer environment and economic sustainability. The application of valorized by-products developed from the shrimp shell wastes and physical methods to improve the pretreatment process of shellfish wastes for valorization are also highlighted in this paper.

GC-MS-Based Metabolomics Analysis of Prawn Shell Waste Co-Fermentation by Lactobacillus plantarum and Bacillus subtilis

GC-MS-based metabolomics were used to investigate metabolic changes in prawn shell waste during fermentation. Microbial strains Lactobacillus plantarum and Bacillus subtilis were co-fermented in a shake flask comprising of 5% (w/v) prawn shell waste and 20% (w/v) glucose as a carbon source. Analysis of the prawn shell waste fermentation showed a total of 376 metabolites detected in the culture supernatant, including 14 amino acids, 106 organic acids, and 90 antimicrobial molecules. Results show that the liquid fraction of the co-fermentation is promising for harvesting valuable metabolites for probiotics application.

Recent insights into the extraction, characterization, and bioactivities of chitin and chitosan from insects

Background

Insects are a living resource used for human nutrition, medicine, and industry. Several potential sources of proteins, peptides, and biopolymers, such as silk, chitin, and chitosan are utilized in industry and for biotechnology applications. Chitosan is an amino-polysaccharide derivative of chitin that consists of linear amino polysaccharides with d-glucosamine and N-acetyl-d-glucosamine units. Currently, the chief commercial sources of chitin and chitosan are crustacean shells that accumulate as a major waste product from the marine food industry. Existing chitin resources have some natural challenges, including insufficient supplies, seasonal availability, and environmental pollution. As an alternative, insects could be utilized as unconventional but feasible sources of chitin and chitosan.

Scope and approach

This review focuses on the recent sources of insect chitin and chitosan, particularly from the Lepidoptera, Coleoptera, Orthoptera, Hymenoptera, Diptera, Hemiptera, Dictyoptera, and Odonata orders. In addition, the extraction methods and physicochemical characteristics are discussed. Insect chitin and chitosan have numerous biological activities and could be used for food, biomedical, and industrial applications.

Key findings and conclusions

Recently, the invasive and harmful effects of insect species causing severe damage in agricultural crops has led to great economic losses globally. These dangerous species serve as potential sources of chitin and are underutilized worldwide. The conclusion of the present study provides better insight into the conversion of insect waste-derived chitin into value-added products as an alternative chitin source to address food security related challenges.

Green, Simple, and Effective Process for the Comprehensive Utilization of Shrimp Shell Waste

An environmentally friendly approach for the comprehensive utilization of shrimp shell waste was reported. Instant catapult steam explosion (ICSE) was employed for shrimp shell waste pretreatment. After ICSE, lower crystallinity and greater surface areas of shrimp shells were achieved, which significantly enhanced the extraction of chitin. Compared to the traditional method, weaker organic acid (HCOOH) and much lower dosages of KOH (90% molar less) were used, and chitin with a high demineralization rate (98.2%) and deproteinization rate (97.7%) was obtained. The wastewater was neutralized by simply intermixing, and it was recycled as a potential plant fertilizer because it contained more oligopeptides, calcium, and potassium, but it was less salty and therefore non-toxic to plants. The whole process produced less solid waste and no waste water. The obtained chitin also showed a low degree of acetylation (50.5%), which demonstrates the potential for environmentally friendly preparation of chitosan in dilute alkali through ICSE.

A comparison of chitosan properties after extraction from shrimp shells by diluted and concentrated acids

Chitosan and chitin are mainly extracted from shells of fish such as lobsters, crabs or shrimps. Originally, the raw material and the two compounds are identical. This study aims to show the acid concentration effect on chitosan extraction from shrimp shells between concentrated and diluted acid; on surface morphology, thermal resistance, structural, elemental composition, optical and opto-electronic properties. It also aims to reduce the production time and increase the quantity. We focused mainly on comparing between Physico-chemical properties of chitosans extracted by diluted (1M) and concentrated (20%) Chloric acids, and sometimes we compare by other concentrated acids like nitric acid (70%) and sulphuric acid (98%). We performed the product's characterization by various tools such as: X-ray diffraction (XRD) spectroscopy, X-ray fluorescence (XRF) analysis, UV-Visible spectroscopy, Fourier Transformed Infra-Red (FTIR), Raman Spectroscopy, Thermogravimetry and Derivative Thermogravimetry (TG/DTG), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) analysis. The elemental analysis (XRF and EDX). The results showed that all chitosan samples we gained are good about 80% degree of deacetylation, and pure mostly composed by carbon between (15,02% - 45.55%), nitrogen (4,17% - 12.28%) and oxygen (42.16% and 81.25%), with appearance of essential peaks for chitosan in Raman analysis: 470 cm⁻¹ → ν(C-C(=O)-C), 1000 cm⁻¹ → ν(C-H), 1800 cm⁻¹ → δ(C=CCOOR), δ(C=O), 2630 cm⁻¹ → δ(CH) rings, 3250 cm⁻¹ → ν(NH₂). All our chitosan particles are ultrafine nanoscale between 8 and 34 nm.

Exploration of Chitinous Scaffold-Based Interfaces for Glucose Sensing Assemblies

: The nanomaterial-integrated chitinous polymers have promoted the technological advancements in personal health care apparatus, particularly for enzyme-based devices like the glucometer. Chitin and chitosan, being natural biopolymers, have attracted great attention in the field of biocatalysts engineering. Their remarkable tunable properties have been explored for enhancing enzyme performance and biosensor advancements. Currently, incorporation of nanomaterials in chitin and chitosan-based biosensors are also widely exploited for enzyme stability and interference-free detection. Therefore, in this review, we focus on various innovative multi-faceted strategies used for the fabrication of biological assemblies using chitinous biomaterial interface. We aim to summarize the current development on chitin/chitosan and their nano-architecture scaffolds for interdisciplinary biosensor research, especially for analytes like glucose. This review article will be useful for understanding the overall multifunctional aspects and progress of chitin and chitosan-based polysaccharides in the food, biomedical, pharmaceutical, environmental, and other diverse applications.

Key process parameters involved in the treatment of olive mill wastewater by membrane bioreactor

The Olive Mill Wastewater (OMWW) biodegradation in an external ceramic membrane bioreactor (MBR) was investigated with a starting acclimation step with a Ultrafiltration (UF) membrane (150 kDa) and no sludge discharge in order to develop a specific biomass adapted to OMWW biodegradation. After acclimation step, UF was replaced by an Microfiltration (MF) membrane (0.1 µm). Sludge Retention Time (SRT) was set around 25 days and Food to Microorganisms ratio (F/M) was fixed at 0.2 kg_COD kg_MLVSS^-1 d^-1. At stable state, removal of the main phenolic compounds (hydroxytyrosol and tyrosol) and Chemical Oxygen Demand (COD) were successfully reached (95% both). Considered as a predominant fouling factor, but never quantified in MBR treated OMWW, Soluble Microbial Products (SMP) proteins, polysaccharides and humic substances concentrations were determined (80, 110 and 360 mg L^-1 respectively). At the same time, fouling was easily managed due to favourable hydraulic conditions of external ceramic MBR. Therefore, OMWW could be efficiently and durably treated by an MF MBR process under adapted operating parameters.

Effects of chitosan-supplemented diets on the growth performance, nonspecific immunity and health of loach fish (Misgurnus anguillicadatus)

This study investigated the effects of dietary chitosan on the growth performance and nonspecific immunity of loaches (Misgurnus anguillicadatus). Four practical diets at three levels of chitosan (1, 5 and 10 g/kg) were fed to loach (3.13 ± 0.02 g) in triplicate groups (20 fish per replicate) for 10 weeks. Contrary to high-chitosan treatment, the administration of low or moderate levels of oral chitosan (1 or 5 g/kg) significantly increased the body weight gain, specific growth rate and condition factor. The oral administration of chitosan significantly increased the survival rate, phenoloxidase, superoxide dismutase, glutathione peroxidase, lysozyme, acid phosphatase and alkaline phosphatase activities, as well as the immunoglobulin M and complement 3 contents and the disease resistance against Aeromonas hydrophila. The optimum dose of dietary chitosan required for the maximum growth of loach was 5 g/kg. These results indicated that chitosan exerted immunostimulatory effects on loaches (M. anguillicadatus) and can thus be used as a dietary supplement.

Recovery of high value-added protein from enzyme-assisted aqueous extraction (EAE) of soybeans by dead-end ultrafiltration

The skim fraction (SF) obtained from enzyme-assisted aqueous extraction (EAE) of soybeans is a by-product with high protein content of up to 60.67%. As such, it is of great interest to develop an efficient method to recover protein from this fraction. In this study, the potential of dead-end ultrafiltration (UF) in recovering skim protein extracted with different proteases was evaluated. Two polyethersulfone (PES) membranes with molecular weight cutoffs (MWCO) of 3 kDa and 5 kDa were utilized. Results revealed that the membrane with the MWCO of 5 kDa exhibited better filtration efficiency, since higher permeate flux values and lower impurity rejections were observed. Compared with Flavourzyme and Protex 7L, Alcalase 2.4L and Protex 6L exhibited stronger hydrolyzing ability, resulting in higher filtration fluxes but lower protein rejection coefficients. The recovered protein showed comparable amino acid profile to SPC, while with significantly reduced levels of trypsin inhibitors and phytate (p < 0.05), indicating high quality of the recovered protein. Overall, UF can be applicable to recover high value-added protein from EAE of soybeans and remove undesired components from the resulting protein products.

Influence of conventional and recent extraction technologies on physicochemical properties of bioactive macromolecules from natural sources: A review

The incorporation of bioactive macromolecules from natural sources into marketable functional foods and nutraceuticals is of major significance to the agri-food sector. Interest in this area of research stems from the application of purified bioactive macromolecules in enhancing food quality and as an alternative to some pharmaceutical drugs for delivery of potential health benefits, with less associated adverse effects. To obtain bioactive macromolecules of high quality, appropriate use of extraction techniques and its influence on sensory and physicochemical properties is paramount. With the advent of technology-aided processes, there has been remarkable improvement in the extraction efficiency of these bioactive agents. An overview of the influence of these new techniques on extraction efficiency and physicochemical properties of proteins, lipids and fibers, which this detailed review provides, will prove to be a valuable resource to food industries aiming to maximize production of bioactive macromolecules from natural sources as well as the scientific community.

Extraction, chemical modification and characterization of chitin and chitosan

Chitin is the second most common polymer after cellulose in earth, existing in the shells of crustaceans like crab and shrimp. Chitosan is a natural amino-polysaccharide derived from chitin, known as one of the most abundant organic materials in nature, it has been widely used in several applications due to its natural origin and exceptional properties such as biocompatibility, biodegradability, non-toxicity, and chelating of metal ions. Chitin and chitosan are characterized by deacetylation degree, one of the most important chemical characteristics that can influence the performance of chitosan in many applications. Chitosan is usually prepared by a thermochemical method, consuming time, energy and reagents. In this review, various methods of chitosan extraction will be approached and compared; the importance of a new method of ecological extraction will be emphasized. Moreover, in order to improve the chitosan functionality, and better control these physicochemical properties, several chemical modifications have been reported. These chemical modifications lead to a broad range of derivatives with a wide range of applications in many fields. Recent examples of the distinct applications, with particular emphasis on environmental applications, have been presented.

The role of ozone pretreatment on optimization of membrane bioreactor for treatment of oil sands process-affected water

Previously, anoxic-aerobic membrane bioreactor (MBR) coupled with mild ozonation pretreatment has been applied to remove toxic naphthenic acids (NAs) in oil sands process-affected water (OSPW). To further improve MBR performance, the optimal operation conditions including hydraulic retention time (HRT) and initial ammonia nitrogen (NH₄⁺-N) need to be explored. In this study, the role of ozone pretreatment on MBR optimization was investigated. Compared with MBR treating raw OSPW, MBR treating ozonated OSPW had the same optimal operation conditions (HRT of 12 h and NH₄⁺-N concentration of 25 mg/L). Nevertheless, MBR performance benefited from HRT adjustment more after ozone pretreatment. HRT adjustment resulted in NA removal in the range of 33-50% for the treatment of ozonated OSPW whereas NA removal for raw OSPW only fluctuated between 27% and 38%. Compared with the removal of classical NAs, the degradation of oxidized NAs was more sensitive to the adjustment of operation conditions. Adjusting HRT increased the removal of oxidized NAs in ozonated OSPW substantially (from 6% to 35%). It was also noticed that microbial communities in MBR treating ozonated OSPW were more responsive to the adjustment of operation conditions as indicated by the noticeable increase of Shannon index and extended genetic distances.

Levofloxacin is phytotoxic and modifies the protein profile of lupin seedlings

The toxicity of levofloxacin to yellow lupin plants was evaluated in this study. Recommended indexes of plant (roots and shoots) growth were determined and new indexes were proposed which better characterise the phytotoxicity of levofloxacin. These were, in particular, the activity of antioxidative enzymes, the content of free radicals, as well as the root protein content and the root protein profile. The results showed that levofloxacin considerably affected EC₅₀, measured as the activity of catalase in roots, and leaves (1.05 and 0.069 mM, respectively). The activity of peroxidase in the roots and the dry weight of seedlings were the least sensitive parameters (EC₅₀ was 1.8 and 1.76 mM, respectively). Units of toxicity clearly showed that the activity of catalase is a better measure of toxicity for low concentrations of the drug, and it is a better index of plant physiological state than the morphological parameters of seedlings. Moreover, levofloxacin changed the location of free radicals and the protein profile in plants. The changes in location of reactive oxygen species in roots were an important symptom of the drug toxicity to lupin seedlings. Our results have shown that the toxicity of levofloxacin was manifested mainly by changes in the protein profile. The content of the glyceraldehyde-3-phosphate dehydrogenase, 14-3-3-like protein A, expansin-B3-like precursor, fructose-bisphosphate aldolase, lipoxygenase, nucleotide-binding subunit of vacuolar ATPase and pyruvate dehydrogenase were found to decrease. On the other hand, plant exposure to levofloxacin resulted in an increase in the content of enolase, protein LlR18A, class III chitinase, ascorbate peroxidase, aspartate aminotransferase, alcohol dehydrogenase 1, leghemoglobin reductase-like 17 and heat shock cognate protein 80-like.

Chitin and chitosan preparation from shrimp shells Penaeus monodon and its human ovarian cancer cell line, PA-1

In the present study, chitin and chitosan preparation from shrimp shells Penaeus mondon and its ovarian cancer cell line (PA-1). FTIR spectrum sharp absorption peak at 1655cm^-1 is assigned to ketone C=O (α) unsaturated with chitosan. X-ray diffraction showed the presence of chitin and chitosan were strongest peak at 18.91° (β) and 29.75° (α) characters. SEM observations of chitin and chitosan surface morphologies of P. monodon showed that microfibril and porous structures. Anticancer activity of chitin and chitosan against human ovarian cancer cell line showed that chitosan an exhibited notable higher activity than chitin. Anticancer activity of aquacultural waste of shrimp shells mediated chitosan, which was proved to be good novel pharmaceutical industries.

Production of Chitin from Penaeus vannamei By-Products to Pilot Plant Scale Using a Combination of Enzymatic and Chemical Processes and Subsequent Optimization of the Chemical Production of Chitosan by Response Surface Methodology

The waste generated from shrimp processing contains valuable materials such as protein, carotenoids, and chitin. The present study describes a process at pilot plant scale to recover chitin from the cephalothorax of Penaeus vannamei using mild conditions. The application of a sequential enzymatic-acid-alkaline treatment yields 30% chitin of comparable purity to commercial sources. Effluents from the process are rich in protein and astaxanthin, and represent inputs for further by-product recovery. As a last step, chitin is deacetylated to produce chitosan; the optimal conditions are established by applying a response surface methodology (RSM). Under these conditions, deacetylation reaches 92% as determined by Proton Nuclear Magnetic Resonance (¹H-NMR), and the molecular weight (Mw) of chitosan is estimated at 82 KDa by gel permeation chromatography (GPC). Chitin and chitosan microstructures are characterized by Scanning Electron Microscopy (SEM).

Purification, characterization and application of dual coagulants containing chitosan and different Al species in coagulation and ultrafiltration process

The objective of this study was to investigate the effect of different Al species and chitosan (CS) dosages on coagulation performance, floc characteristics (floc sizes, strength and regrowth ability and fractal dimension) and membrane resistance in a coagulation-ultrafiltration hybrid process. Results showed that different Al species combined with humic acid in diverse ways. Al_a had better removal efficiency, as determined by UV₂₅₄ and dissolved organic carbon, which could be further improved by the addition of CS. In addition, the optimal dosage of different Al species was determined to be 4.0mg/L with the CS concentration of 1.0mg/L, by orthogonal coagulation experiments. Combining Al_a/Al_b/Al_c with CS resulted in larger flocs, higher recovery, and higher fractal dimension values corresponding to denser flocs; in particular, the floc size at the steady state stage was four times larger than that obtained with Al species coagulants alone. The results of ultrafiltration experiments indicated that the external fouling percentage was significantly higher than that of internal fouling, at around 85% and 15%, respectively. In addition, the total membrane resistance was significantly decreased due to CS addition.

Competitive adsorption of toxic metals on bentonite and use of chitosan as flocculent coagulant to speed up the settling of generated clay suspensions

Evaluation of modified Algerian clay as mineral adsorbent was done for its adsorbing capacity on copper (Cu) and Zinc (Zn) cations. The results obtained show a rapid kinetic adsorption for both metals (less than 2 h) following the pseudo-second order model with high elimination rates of 67.2 and 61.8% for Cu and Zn respectively. The adsorption isotherms analyzed with Langmuir model revealed a correlation with the experimental values. While the use of obtained chitosan at room temperature, as flocculent coagulant, accelerates the decantation of the colloidal particles in suspension generated after adsorption process.

Current Status and New Perspectives on Chitin and Chitosan as Functional Biopolymers

The natural biopolymer chitin and its deacetylated product chitosan are found abundantly in nature as structural building blocks and are used in all sectors of human activities like materials science, nutrition, health care, and energy. Far from being fully recognized, these polymers are able to open opportunities for completely novel applications due to their exceptional properties which an economic value is intrinsically entrapped. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal and insect sources. Significant efforts have been devoted to commercialize chitosan extracted from fungal and insect sources to completely replace crustacean-derived chitosan. However, the traditional chitin extraction processes are laden with many disadvantages. The present review discusses the potential bioextraction of chitosan from fungal, insect, and crustacean as well as its superior physico-chemical properties. The different aspects of fungal, insects, and crustacean chitosan extraction methods and various parameters having an effect on the yield of chitin and chitosan are discussed in detail. In addition, this review also deals with essential attributes of chitosan for high value-added applications in different fields and highlighted new perspectives on the production of chitin and deacetylated chitosan from different sources with the concomitant reduction of the environmental impact.

Utilization of protein-rich residues in biotechnological processes

A drawback of biotechnological processes, where microorganisms convert biomass constituents, such as starch, cellulose, hemicelluloses, lipids, and proteins, into wanted products, is the economic feasibility. Particularly the cost of nitrogen sources in biotechnological processes can make up a large fraction of total process expenses. To further develop the bioeconomy, it is of considerable interest to substitute cost-intensive by inexpensive nitrogen sources. The aim of this mini-review was to provide a comprehensive insight of utilization methods of protein-rich residues, such as fish waste, green biomass, hairs, and food waste. The methods described include (i) production of enzymes, (ii) recovery of bioactive compounds, and/or (iii) usage as nitrogen source for microorganisms in biotechnological processes. In this aspect, the utilization of protein-rich residues, which are conventionally considered as waste, allows the development of value-adding processes for the production of bioactive compounds, biomolecules, chemicals, and materials.

Magnetic field on fouling control of ultrafiltration membranes applied in treatment of a synthetic textile effluent

Membrane performance is decreased by fouling, reducing permeate flux and membrane lifespan. This paper assesses ultrafiltration of a model textile effluent assisted by permanent magnetic field as an alternative to improve the water permeability recovery. Ultrafiltration was performed in a tangential module and model solutions, composed of carboxymethylcellulose (CMC) and sodium sulphate (Na2SO4). The feed was permeated through 30 kDa polysulphone membrane with and without the presence of a permanent magnetic field of 0.41 T, perpendicular to the membrane surface. Magnetic induction (MI) of feed solution was also investigated by recirculation of the feed stream through the magnetic field for 3 h. The increase in feed concentration did not affect permeate flux, while the presence of salt resulted in a severe flux decline. Effective water permeability recovery was obtained when the magnetic field was applied in the ultrafiltration process, although the MI of the CMC and Na2SO4 solutions also caused some enhancement in permeability recovery. Scanning electron microscopy images showed differences between the assays done with and without the presence of magnetic field. The magnetic field application in ultrafiltration of CMC and Na2SO4 solutions has proved to be an attractive alternative for improving the permeability recovery.

Effects of chitin and its derivatives on human cancer cells lines

The present study is focused on the effect of chitin derivatives against human cancer cell lines RD and Hep2. As an outcome from this research, chitin was cytotoxic at IC50 = 400 μg/ml and 200 μg/ml against Hep2 cells and RD cells lines, respectively. Irradiated chitin had an IC50 value of 450 μg/ml for Hep2 and an IC50 of 200 μg/ml for RD. The lowest IC50 is attributed to chitosan, 300 μg/ml in Hep2 and 190 μg/ml in RD.