Chitin extraction from shrimp shell using enzymatic treatment. Antitumor, antioxidant and antimicrobial activities of chitosan

A review of chitosan role in milk bioactive-based drug delivery, smart packaging and biosensors: Recent advances and developments

Chitosan, a versatile biopolymer derived from chitin, is increasingly recognized in the milk industry for its multifunctional applications in drug delivery, smart packaging, and biosensor development. This review provides a comprehensive analysis of recent advances in chitosan production techniques. These include chemical, biological, and novel methods such as deep eutectic solvents (DES), microwave-assisted approaches, and laser-assisted processes. Surface modification strategies to enhance its functional properties are also discussed. The review highlights the development of various chitosan-based nanocarriers, including nanoparticles, nanofibers, nanogels, and nanocomposites. It emphasizes their stability when combined with milk bioactive ingredients like lipids, peptides, lactose, and minerals. The gastrointestinal fate and safety of chitosan nanoparticles are critically evaluated, showcasing their potential for safe consumption in dairy-related applications. In drug delivery systems, chitosan exhibits excellent compatibility with milk-derived carbohydrates, proteins, and minerals, enabling the development of innovative drug delivery platforms. Additionally, its incorporation into smart packaging materials enhances the shelf-life and quality of dairy products. Chitosan-based biosensors offer precise contaminant detection in the milk industry by enabling precise detection of contaminants such as Bisphenol A, melamine, bacteria, drugs, antibiotics, toxins, heavy metals, and allergens, thus ensuring food safety and quality. Emerging trends, including the integration of artificial intelligence, advanced gene editing, and multifunctional chitosan, are discussed, offering insights into future personalized delivery systems and merging food and drug technologies. The review concludes by highlighting gaps in current research and offering recommendations for future exploration. These suggestions aim to optimize chitosan's unique properties to address key challenges in the milk industry. This article serves as a valuable resource for researchers, industry professionals, and policymakers aiming to innovate within the dairy sector using chitosan-based technologies.

Bioactive compounds in edible insects: Aspects of cultivation, processing and nutrition

The increasing interest in edible insects, driven by projected global population growth and environmental concerns, has led to the exploration of their potential in the food sector. Edible insects are abundant in macronutrients, such as proteins, lipids and chitin, as well as micronutrients, such as minerals, vitamins and phenolic compounds. Considering their content of bioactive compounds, they offer a sustainable solution to meet future food demands while providing potential health benefits. This review identifies bioactive peptides, phenolic compounds, chitosan, and vitamins as major bioactive ingredients derived from insects. It discusses their presence in various edible insect species, their primary bioactive properties, and methods for production and isolation. Bioactive compounds sourced from edible insects exhibit antioxidant, antimicrobial, and disease-preventing properties. Insects also serve as rich sources of vitamins A, B2, B6, B12, D, and E, albeit with variations in content among species and life stages. However, the consumption of insects poses risks related to their biological and chemical contaminants, as well as their allergenicity. Managed diets in farm-bred insects ensure controlled nutrient levels, highlighting their potential as sustainable sources of bioactive compounds for human health. Adequate processing and labeling of insect-derived products can reduce the risk of insect consumption. In conclusion, the bioactive compound profile of edible insects complements their nutritional richness and highlights their potential to address future nutrition and food security.

Chitin isolation from crustaceans and mushrooms: The need for quantitative assessment

This review examines key journal articles on the isolation of chitin from mushroom biomass comparing these findings to those related to crustacean chitin. It highlights the need for standardizing chitin characterization, emphasizing that chitin comprises a family of polymers with variations in molecular weight (Mw), degree of acetylation (%DA), and acetylation patterns (PA), leading to diverse physicochemical properties and biological activities. The review positions fungi and mushrooms as emerging sources of 'vegan' chitin, being non-animal and free from allergenic proteins. Their ability to be cultivated year-round, along with rapid growth and low-cost biowaste substrates, makes them attractive alternatives to crustacean chitin. Market adoption of mushroom chitin will depend on its potential applications in high-value products. Traditionally, chitin characterization has been semi-qualitative, but there is now a growing recognition of how sample inconsistencies impact research quality. This review underscores the importance of quantitative analysis for achieving practical, repeatable, and reproducible results while addressing the challenges in characterizing fungal chitin. We argue that accurately determining the properties of fungal chitin is essential and should be a fundamental aspect of every study, as these properties significantly influence the polymer's characteristics and biological activity.

Eco-friendly Strategy for Producing Bio-based Silver Nanoparticles (AgNPs) Employing Sepioteuthis lessoniana ink, in Addition to Biological and Degradation of Dye Applications

The squid, Sepioteuthis lessoniana, is a remarkable fishery product which is exported by many nations for use in industrial production or human consumption. This study focused on the synthesis of silver nanoparticles (AgNPs) from squid ink (SI) and its wide range of applications. The formation of the nanoparticles was confirmed through UV-Visible spectroscopy, FTIR, XRD, SEM with EDX, DLS, and zeta potential analysis. The results showed a strong absorbance peak at 407 nm, the presence of various functional groups, a nanocrystalline structure with a crystalline size of 17.56 nm, spherical-shaped particles with an average size of 76 nm, and the presence of the highest % mass of Ag and uniformly dispersed particles, respectively. The bioactivity of the synthesized squid ink silver nanoparticles was analyzed through antibacterial, antioxidant, anticancer, and toxicity studies. The dye degradation assay was also analyzed as a means of wastewater treatment for different industrial dyes. The antibacterial activity showed the highest zone of inhibition of 24 mm at a concentration of 100 μg/ml against Escherichia coli, followed by other tested strains. The nitric oxide radical scavenging assay showed the highest antioxidant activity (92%) at a concentration of 100 μg/ml. The cytotoxic ability of SI-AgNPs against the MDA-MB-231 breast cancer cell line revealed an IC50 value of 4.52 μg/ml. The toxicity study revealed a dose and time-dependent activity with the LC50 value of 5.090 and 3.303 mg/ml for 24 and 48 h, respectively. The successful degradation of dyes by SI-AgNPs is attributed to the cooperative action of the electron relay system with Ag as a catalyst and SI as a catalytic support. These findings indicate that SI-AgNPs are a novel potential product that should be further studied to improve its pharmacological, biomedical, and environmental applications.

Waste-to-resource: Extraction and transformation of aquatic biomaterials for regenerative medicine

The fisheries and aquaculture industry are known for generating substantial waste or by-products, often underutilized, or relegated to low-value purposes. However, this overlooked segment harbors a rich repository of valuable bioactive materials of which have a broad-spectrum of high-value applications. As the blue economy gains momentum and fisheries expand, sustainable exploitation of these aquatic resources is increasingly prioritized. In this review, we present a comprehensive overview of technology-enabled methods for extracting and transforming aquatic waste into valuable biomaterials and their recent advances in regenerative medicine applications, focusing on marine collagen, chitin/chitosan, calcium phosphate and bioactive-peptides. We discuss the inherent bioactive qualities of these "waste-to-resource" aquatic biomaterials and identify opportunities for their use in regenerative medicine to advance healthcare while achieving the Sustainable Development Goals.

Biotransformation of insect processing residues: Production of lactic acid bacterial biomass and associated partial removal of proteins from chitin

Processing of edible insects typically involves fractionating into high-value food ingredients, which results in by-products containing chitin and insoluble proteins. This study examined the effectiveness of lactic acid bacteria (LAB) in removing proteins from chitin in insect processing residues. Lesser mealworm processing residues were biologically treated for 48 and 120 h using LAB strains without added carbon sources. Results showed partial deproteinization, up to 29 % with Levilactobacillus brevis after 120 h. Most LAB grew up to 2 log10 colony-forming units/mL in the first 48 h. Confocal microscopy and Fourier-transform infrared spectra indicated that some protein remained attached to chitin. The molecular weight of solubilized proteins was affected by strain and time of incubation, with antioxidant activity increasing significantly after 120 h with Lacticaseibacillus paracasei. The biological treatment of insect processing streams can be a sustainable approach to producing high amounts of LAB biomass with subsequent protein solubilization and chitin release.

Exploring the potential of chitosan from royal shrimp waste for elaboration of chitosan/bioglass biocomposite: Characterization and "in vitro" bioactivity

Exploiting royal shrimp waste to produce value-added biocomposites offers environmental and therapeutic benefits. This study proposes biocomposites based on chitosan and bioglass, using shrimp waste as the chitosan source. Chitin extraction and chitosan preparation were characterized using various analytical techniques. The waste composition revealed 24 % chitin, convertible to chitosan, with shells containing 77.33-ppm calcium. (X-ray diffraction) XRD analysis showed crystallinity index of 54.71 % for chitin and 49.14 % for chitosan. Thermal analysis indicated degradation rates of 326 °C and 322 °C, respectively. The degree of deacetylation of chitosan was 97.08 % determined by proton nuclear magnetic resonance (1H-NMR) analysis, with an intrinsic viscosity of 498 mL.g-1 and molar mass of 101,720 g/mol, showing improved solubility in 0.3 % acetic acid. Royal chitosan (CHR) was combined with bioglass (BG) via freeze-drying to create a CHR/BG biocomposite for bone surgery applications. The bioactivity of the CHR/BG was tested in simulated body fluid (SBF), revealing a biologically active apatite layer on its surface. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis confirmed enhanced bioactivity of the CHR/BG compared to commercial chitosan. The CHR/BG biocomposite demonstrated excellent apatite formation, validated by Scanning Electron Microscopy (SEM), highlighting its potential in bone surgery.

Optimization of Enzymatic Deproteination of Northern Shrimp (Pandalus borealis) Shell Chitin Using Commercial Proteases

Shrimp shells are a key source of chitin, commonly extracted through chemical methods, which may cause minor molecular damage. Nowadays, there is great interest in achieving close to zero protein content in crude chitin in order to use it for high-end markets. Therefore, this study optimized the enzymatic deproteination using two commercial proteases (SEB Pro FL100 and Sea-B Zyme L200) for effective and fast removal of residual protein from Northern shrimp (Pandalus borealis) shell chitin for the first time. The protein content was determined using both the Kjeldahl method and amino acid analysis using gas chromatography-mass spectrometry (GC-MS). The performance of papain (Sea B Zyme L200) was superior to fungal protease (SEB Pro FL100) for this application, and it achieved residual protein content of 2.01%, while the calculated optimum for the latter enzyme was 6.18%. A model was developed using 24 factorial design, and it was predicted that the lowest residual protein content using fungal protease and papain could be achieved at the following conditions: a pH of 4.2 and 7, and an enzyme concentration of 4 and 1.5%, respectively. Thus, the low-protein content obtained using enzymatic deproteination could be an alternative approach to the traditional methods, indicating their potential to produce premium-quality chitin.

Biocomposite Scaffolds Based on Chitosan Extraction from Shrimp Shell Waste for Cartilage Tissue Engineering Application

Chitosan-based scaffolding possesses unique properties that make it highly suitable for tissue engineering applications. Chitosan is derived from deacetylating chitin, which is particularly abundant in the shells of crustaceans. This study aimed to extract chitosan from shrimp shell waste (Macrobrachium rosenbergii) and produce biocomposite scaffolds using the extracted chitosan for cartilage tissue engineering applications. Chitinous material from shrimp shell waste was deproteinized and deacetylated. The extracted chitosan was characterized and compared to commercial chitosan through various physicochemical analyses. The findings revealed that the extracted chitosan shares similar trends in the Fourier transform infrared spectroscopy spectrum, energy dispersive X-ray mapping, and X-ray diffraction pattern to commercial chitosan. Despite differences in the degree of deacetylation, these results underscore its comparable quality. The extracted chitosan was mixed with agarose, collagen, and gelatin to produce the blending biocomposite AG-CH-COL-GEL scaffold by freeze-drying method. Results showed AG-CH-COL-GEL scaffolds have a 3D interconnected porous structure with pore size 88-278 μm, high water uptake capacity (>90%), and degradation percentages in 21 days between 5.08% and 30.29%. Mechanical compression testing revealed that the elastic modulus of AG-CH-COL-GEL scaffolds ranged from 44.91 to 201.77 KPa. Moreover, AG-CH-COL-GEL scaffolds have shown significant potential in effectively inducing human chondrocyte proliferation and enhancing aggrecan gene expression. In conclusion, AG-CH-COL-GEL scaffolds emerge as promising candidates for cartilage tissue engineering with their optimal physical properties and excellent biocompatibility. This study highlights the potential of using waste-derived chitosan and opens new avenues for sustainable and effective tissue engineering solutions.

Production of chitosan from shrimp shell using ultrasound followed by subcritical water hydrolysis

The interest in shrimp shell valorization has been growing in line with sustainability goals. Therefore, the main objective of this study was to obtain chitosan from shrimp shell using ultrasound followed by subcritical water treatment. Ultrasonication of shells was performed at 600 and 1200 W for 5 min. Then, shells were hydrolyzed at 140-260 °C and 50 bar for 10-60 min followed by demineralization using citric acid, bleaching using hydrogen peroxide and deacetylation using sodium hydroxide solution. The highest deproteination (80.93 %) was obtained by ultrasonication at 1200 W/5 min followed by subcritical water hydrolysis at 260 °C/50 bar/60 min, where the residue with a yield of 10.56 %, whiteness index of 60.42, degree of deacetylation of 64.27 %, relative crystallinity of 32.66 % and similar functional groups to the commercial sample was obtained. These results indicated that the combination of ultrasound with subcritical water is promising to valorize shrimp shell towards production of value-added compounds.

Low molecular weight chitosan from Pleurotus ostreatus waste and its prebiotic potential

The booming mushroom industry envisages economic merits, and massive unutilized waste production (∼ 20 %) creates an opportunity for valorization. Chitosan, a bioactive polysaccharide, has drawn immense attention for its invaluable therapeutic potential. Thus, the present study was conducted to extract chitosan from mushroom waste (MCH) for its prebiotic potential. The structural characterization of MCH was carried out using NMR, FTIR, and XRD. The CP/MAS-13CNMR spectrum of MCH appeared at δ 57.67 (C2), 61.19 (C6), 75.39 (C3/C5), 83.53 (C4), 105.13 (C1), 23.69 (CH3), and 174.19 (C = O) ppm. The FTIR showed characteristic peaks at 3361 cm-1, 1582 cm-1, and 1262 cm-1 attributed to -NH stretching, amide II, and amide III bands of MCH. XRD interpretation of MCH exhibited a single strong reflection at 2θ =20.19, which may correspond to the "form-II" polymorph. The extracted MCH (∼ 47 kDa) exhibited varying degrees of deacetylation from 79 to 84 %. The prebiotic activity score of 0.73 to 0.82 was observed for MCH (1 %) when supplemented with probiotic strains (Lactobacillus casei, L. helveticus, L. plantarum, and L. rhamnosus). MCH enhanced the growth of Lactobacillus strains and SCFA's levels, particularly in L. rhamnosus. The MCH also inhibited the growth of pathogenic strains (MIC of 0.125 and 0.25 mg/mL against E. coli and S. aureus, respectively) and enhanced the adhesion efficiency of probiotics (3 to 8 % at 1 % MCH supplementation). L. rhamnosus efficiency was higher against pathogens in the presence of MCH, as indicated by anti-adhesion assays. These findings suggested that extracted polysaccharides from mushroom waste can be used as a prebiotic for ameliorating intestinal dysbiosis.

Isolation and Structure Analysis of Chitin Obtained from Different Developmental Stages of the Mulberry Silkworm (Bombyx mori)

Chitin, a ubiquitous biopolymer, holds paramount scientific and economic significance. Historically, it has been primarily isolated from marine crustaceans. However, the surge in demand for chitin and the burgeoning interest in biopolymers have necessitated the exploration of alternative sources. Among these methods, the mulberry silkworm (Bombyx mori) has emerged as a particularly intriguing prospect. To isolate chitin from Bombyx mori, a chemical extraction methodology was employed. This process involved a series of meticulously orchestrated steps, including Folch extraction, demineralization, deproteinization, and decolorization. The resultant chitin was subjected to comprehensive analysis utilizing techniques such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray scattering (WAXS). The obtained results allow us to conclude that the Bombyx mori represents an attractive alternative source of α-chitin.

Injecting hope: chitosan hydrogels as bone regeneration innovators

Spontaneous bone regeneration encounters substantial restrictions in cases of bone defects, demanding external intervention to improve the repair and regeneration procedure. The field of bone tissue engineering (BTE), which embraces a range of disciplines, offers compelling replacements for conventional strategies like autografts, allografts, and xenografts. Among the diverse scaffolding materials utilized in BTE applications, hydrogels have demonstrated great promise as templates for the regeneration of bone owing to their resemblance to the innate extracellular matrix. In spite of the advancement of several biomaterials, chitosan (CS), a natural biopolymer, has garnered significant attention in recent years as a beneficial graft material for producing injectable hydrogels. Injectable hydrogels based on CS formulations provide numerous advantages, including their capacity to absorb and preserve a significant amount of water, their minimally invasive character, the existence of porous structures, and their capability to adapt accurately to irregular defects. Moreover, combining CS with other naturally derived or synthetic polymers and bioactive materials has displayed its effectiveness as a feasible substitute for traditional grafts. We aim to spotlight the composition, production, and physicochemical characteristics and practical utilization of CS-based injectable hydrogels, explicitly focusing on their potential implementations in bone regeneration. We consider this review a fundamental resource and a source of inspiration for future research attempts to pioneer the next era of tissue-engineering scaffold materials.

Characterization and anti-aging activities of polysaccharide from Rana dybowskii Guenther

Introduction: Rana dybowskii Guenther (RDG), as a traditional Chinese medicine, has been shown to have antioxidant effects. However, studies on the anti-aging effect of RDG are still limited. Methods: In this study, we prepared polysaccharides from the skin of RDG (RDGP) by hot water extraction, alcohol precipitation, ion-exchange chromatography and gel chromatography. The proteins were removed using the Sevage method in combination with an enzymatic method. The structural features were analyzed using high-performance gel permeation chromatography, β-elimination reaction and Fourier transform infrared spectra. The anti-aging effect of RDGP was investigated by using D-Gal to establish an aging model in mice, and pathological changes in the hippocampus were observed under a microscope. Results: We obtained the crude polysaccharide DGP from the skin of RDG, with a yield of 61.8%. The free protein was then removed by the Sevage method to obtain DGPI and deproteinated by enzymatic hydrolysis combined with the Sevage method to further remove the bound protein to obtain the high-purity polysaccharide DGPII. Then, DGPIa (1.03 × 105 Da) and DGPIIa (8.42 × 104 Da) were obtained by gel chromatography, monosaccharide composition analysis showed that they were composed of Man, GlcA, GalNAc, Glc, Gal, Fuc with molar ratios of 1: 4.22 : 1.55: 0.18 : 8.05: 0.83 and 0.74 : 1.78: 1: 0.28: 5.37 : 0.36, respectively. The results of the β-elimination reaction indicated the presence of O-glycopeptide bonds in DGPIa. The Morris water maze test indicated that mice treated with DGPIIa exhibited a significantly shorter escape latency and increased time spent in the target quadrant as well as an increase in the number of times they traversed the platform. Pathologic damage to the hippocampus was alleviated in brain tissue stained with hematoxylin-eosin. In addition, DGPIIa enhanced the activities of SOD, CAT, and GSH-Px and inhibited the level of MDA in the serum and brain tissues of aging mice. Discussion: These results suggest that RDGP has potential as a natural antioxidant and provide useful scientific information for anti-aging research.

Shrimp Waste Upcycling: Unveiling the Potential of Polysaccharides, Proteins, Carotenoids, and Fatty Acids with Emphasis on Extraction Techniques and Bioactive Properties

Shrimp processing generates substantial waste, which is rich in valuable components such as polysaccharides, proteins, carotenoids, and fatty acids. This review provides a comprehensive overview of the valorization of shrimp waste, mainly shrimp shells, focusing on extraction methods, bioactivities, and potential applications of these bioactive compounds. Various extraction techniques, including chemical extraction, microbial fermentation, enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, and pressurized techniques are discussed, highlighting their efficacy in isolating polysaccharides, proteins, carotenoids, and fatty acids from shrimp waste. Additionally, the bioactivities associated with these compounds, such as antioxidant, antimicrobial, anti-inflammatory, and antitumor properties, among others, are elucidated, underscoring their potential in pharmaceutical, nutraceutical, and cosmeceutical applications. Furthermore, the review explores current and potential utilization avenues for these bioactive compounds, emphasizing the importance of sustainable resource management and circular economy principles in maximizing the value of shrimp waste. Overall, this review paper aims to provide insights into the multifaceted aspects of shrimp waste valorization, offering valuable information for researchers, industries, and policymakers interested in sustainable resource utilization and waste-management strategies.

Chitosan as excellent bio-macromolecule with myriad of anti-activities in biomedical applications - A review

The aim of the study is to explore the myriad of anti-activities of chitosan - deacylated derivative of chitin in biomedical applications. Chitosan consists of reactive residual amino groups, which can be modified chemically to obtain wide range of derivatives. These derivatives exhibit the controlled physicochemical characteristics, which in turn improve its functional properties. Such derivatives find numerous applications in the field of biomedical science, agriculture, tissue engineering, bone regeneration and environmental science. This study presents a comprehensive overview of the multifarious anti-activities of chitosan and its derivatives in the field of biomedical science including anti-microbial, antioxidant, anti-tumor, anti-HIV, anti-fungal, anti- inflammatory, anti-Alzheimer's, anti-hypertensive and anti-diabetic activity. It briefly details these anti-activities with respect to its mode of action, pharmacological effects and potential applications. It also presents the overview of current research exploring novel derivatives of chitosan and its anti- activities in the recent past. Finally, the review projects the prospective potential of chitosan and its derivatives and expects to encourage the readers to develop new drug delivery systems based on such chitosan derivatives and explore its applications in biomedical science for benefit of mankind.

Exploring the purity of chitin from crustacean sources using deep eutectic solvents: A machine learning approach

OBJECTIVE

Chitin a natural polymer is abundant in several sources such as shells of crustaceans, mollusks, insects, and fungi. Several possible attempts have been made to recover chitin because of its importance in biomedical applications in various forms such as hydrogel, nanoparticles, nanosheets, nanowires, etc. Among them, deep eutectic solvents have gained much consideration because of their eco-friendly and recyclable nature. However, several factors need to be addressed to obtain a pure form of chitin with a high yield. The development of an innovative system for the production of quality chitin is of prime importance and is still challenging.

METHODS

The present study intended to develop a novel and robust approach to investigate chitin purity from various crustacean shell wastes using deep eutectic solvents. This investigation will assist in envisaging the important influencing parameters to obtain a pure form of chitin via a machine learning approach. Different machine learning algorithms have been proposed to model chitin purity by considering the enormous experimental dataset retrieved from previously conducted experiments. Several input variables have been selected to assess chitin purity as the output variable.

RESULTS

The statistical criteria of the proposed model have been critically investigated and it was observed that the results indicate XGBoost has the maximum predictive accuracy of 0.95 compared with other selected models. The RMSE and MAE values were also minimal in the XGBoost model. In addition, it revealed better input variables to obtain pure chitin with minimal processing time.

CONCLUSION

This study validates that machine learning paves the way for complex problems with substantial datasets and can be an inexpensive and time-saving model for analyzing chitin purity from crustacean shells.

Hydrogels based on seafood chitin: From extraction to the development

Chitin is extensively applied in vast applications due to its excellent biological properties, such as biodegradable and non-toxic. About 50 % of waste generated during seafood processing is chitin. Conventionally, chitin is extracted via chemical method. However, it has many shortcomings. Many novel extraction methods have emerged, including enzymatic hydrolysis, microbial fermentation, ultrasonic or microwave-assisted, ionic liquids, and deep eutectic solvents. Chitin and its derivatives-based hydrogels have attracted much attention due to their excellent properties. Nevertheless, they all have many limitations. Therefore, the preparation and application of chitin and its derivatives-based hydrogels are still facing great challenges. This review focuses on the challenges and prospects for sustainable chitin extraction from seafood waste and the preparation and application of chitin and its derivatives-based hydrogels. First section summarizes the mechanism and application of several methods of extracting chitin. The different extraction methods were evaluated from the aspects of yield, degree of acetylation, and protein and mineral residuals. The shortcomings of the extraction methods are also discussed. Next section summarizes the preparation and application of chitin and its derivatives-based hydrogels. Overall, we hope this mini-review can provide a practical reference for selecting chitin extraction methods from seafood and applying chitin and its derivatives-based hydrogels.

Investigation of Metabolite Differences in Salted Shrimp Varieties during Fermentation

Fermentation of salted shrimp involves the interaction of multiple factors. However, studies of the effects of shrimp variety and fermentation temperature on metabolites generated during fermentation are limited. Therefore, we investigated the effects of the shrimp variety, fermentation temperature, and fermentation period on the composition of fermented salted shrimp. Four different varieties of salted shrimp, namely, Detteugijeot (SSA), Red shrimp jeot (SSB), Chujeot (SSC), and Yukjeot (SSD), were prepared and stored at 5 and 10 °C for 5 months. The pH values ranged from 6.71 to 6.99, with SSD showing the lowest pH at both temperatures. Although total nitrogen content remained relatively constant, amino nitrogen exhibited an upward trend after 2 months and was particularly increased at 10 °C. This increase was attributed to variations in microorganisms and enzymes in the salted shrimp. Except for proline, citrulline, and ornithine, amino acid levels increased during fermentation with the highest amounts detected in SSA. Additionally, the levels of glutamic acid and branched-chain amino acids were found to be sensitive to fermentation temperature. Amino acid levels were apparently affected by species-specific metabolic pathways of the microorganisms present in each salted shrimp. Compared to the other varieties, SSB had significantly higher contents of adenosine triphosphate and hypoxanthine. A high hypoxanthine content could contribute to increased bitterness and an umami taste profile. Furthermore, the correlation between salted shrimp and metabolites was unique in SSB, whereas partial clustering was observed between the SSA and SSC.

Investigation on Akis granulifera (Coleoptera, Sahlberg, 1823) as a potential source of chitin and chitosan: Extraction, characterization and hydrogel formation

The majority of studies have focused on the industrial exploitation of marine fisheries waste through the production of natural bioactive bioploymeres such as chitin and chitosan. However, in recent years, beetles are increasingly attracting the interest of scientists as a source of chitin and chitosan for the preparation of hydrogels for sustainable engineering development. In the present work, we focus on the study for the first time a new Moroccan species of beetle (Akis granulifera Sahlberg, 1823), for the extraction of chitin and the elaboration of chitosan. A chemical extraction process was used. Then, physicochemical characterizations by FT-IR, SEM, XRD, 1H NMR, TGA/DSC, Potentiometry, Viscosimetry, and elemental analysis were performed. In addition, to evaluate its physicochemical quality, the elaborated chitosan is combined with alginate to form a hydrogel. This hydrogel was effectively characterized by SEM, DRX and FTIR to show the potential of chitosan from Akis granulifera in biomaterial applications.

Physicochemical characterization and therapeutic potential of ink from squid, Sepioteuthis lessoniana

In the current study, the squid, Sepioteuthis lessoniana ink was used as a raw material. It summarizes physicochemical, elemental, and spectral properties (UV/Visible spectroscopy and FT-IR) of crude ink, whereas the biochemical analysis was performed with crude ink (CI) as well as melanin-free ink (MFI). The percentage yield was analyzed using various solvent extracts of CI and MFI. GC-MS was performed for the chemical constituents of the methanolic extract of ink. Furthermore, the methanolic extract was subjected to various biological applications. The physicochemical analysis defines the presence of moisture, ash, extractive value, solubility, and thermal stability of CI. The biochemical analysis reveals protein, lipid, and carbohydrate of 2.5, 2.2, and 2.37 mg/ml for CI and 2.8, 3.7, and 4.51 mg/ml for MFI respectively. The extract showed the highest zone of inhibition at 100 μg/ml. The antioxidant activity reveals the highest percentage of radical-scavenging activity in nitric oxide (NO) (89%), and total antioxidant capacity (TAC) assay showed the highest inhibition activity of 0.41 nm at 100 µg/ml. The cytotoxic ability of methanolic extract against MDA-MB-231 breast cancer cell line revealed an IC50 value of 10.13 μg/ml. Toxicity assay showed increased mortality of Artemia nauplii at higher concentrations (1000 ppm/40%) of extract. These findings indicate that S. lessoniana ink is a novel prospective product that needs to be characterized in order to increase its pharmacological activity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03830-6.

Chemical extraction, characterization, and inspection of the antimicrobial and antibiofilm activities of shrimp chitosan against foodborne fungi and bacteria

Nowadays, the exploitation of biopolymers in the industrial sector has become a trend. Chitosan is considered one of the most investigated biopolymers due to its abundance and antibacterial, antifungal, and antibiofilm activities. In this work, chitosan was chemically extracted from shrimp shells. Solutions of HCl 1 M, NaOH 4 M, and NaOH 15 M were used for the demineralization, deproteinization, and deacetylation process, respectively. The utilized methods of characterization (FTIR, 1 H NMR, 13 C NMR, and SEC-MALS) revealed that the obtained chitosan has a moderate degree of deacetylation and low molecular weight (DDA = 74% and Mw = 72.14 kDa). The microdilution method and inoculation of solid medium were carried out to assess the antibiofilm action of chitosan against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus hirae, Escherichia coli, Rhizopus sp., and Aspergillus sp. which are known as foodborne microorganisms. Results showed that the produced chitosan at 1 g/L inhibits between 63.44 and 99.75% of the microbial biofilm depending on the tested strains. These promising results confirm the potential deployment of the obtained chitosan in the food industry as a replacement for synthetic antimicrobial agents.

Trash to Treasure: An Up-to-Date Understanding of the Valorization of Seafood By-Products, Targeting the Major Bioactive Compounds

Fishery production is exponentially growing, and its by-products negatively impact industries' economic and environmental status. The large amount of bioactive micro- and macromolecules in fishery by-products, including lipids, proteins, peptides, amino acids, vitamins, carotenoids, enzymes, collagen, gelatin, chitin, chitosan, and fucoidan, need to be utilized through effective strategies and proper management. Due to the bioactive and healthy compounds in fishery discards, these components can be used as functional food ingredients. Fishery discards have inorganic or organic value to add to or implement in various sectors (such as the agriculture, medical, and pharmaceutical industries). However, the best use of these postharvest raw materials for human welfare remains unelucidated in the scientific community. This review article describes the most useful techniques and methods, such as obtaining proteins and peptides, fatty acids, enzymes, minerals, and carotenoids, as well as collagen, gelatin, and polysaccharides such as chitin-chitosan and fucoidan, to ensure the best use of fishery discards. Marine-derived bioactive compounds have biological activities, such as antioxidant, anticancer, antidiabetic, anti-inflammatory, and antimicrobial activities. These high-value compounds are used in various industrial sectors, such as the food and cosmetic industries, owing to their unique functional and characteristic structures. This study aimed to determine the gap between misused fishery discards and their effects on the environment and create awareness for the complete valorization of fishery discards, targeting a sustainable world.

Proteomic and Transcriptomic Analyses to Decipher the Chitinolytic Response of Jeongeupia spp

In nature, chitin, the most abundant marine biopolymer, does not accumulate due to the action of chitinolytic organisms, whose saccharification systems provide instructional blueprints for effective chitin conversion. Therefore, discovery and deconstruction of chitinolytic machineries and associated enzyme systems are essential for the advancement of biotechnological chitin valorization. Through combined investigation of the chitin-induced secretome with differential proteomic and transcriptomic analyses, a holistic system biology approach has been applied to unravel the chitin response mechanisms in the Gram-negative Jeongeupia wiesaeckerbachi. Hereby, the majority of the genome-encoded chitinolytic machinery, consisting of various glycoside hydrolases and a lytic polysaccharide monooxygenase, could be detected extracellularly. Intracellular proteomics revealed a distinct translation pattern with significant upregulation of glucosamine transport, metabolism, and chemotaxis-associated proteins. While the differential transcriptomic results suggested the overall recruitment of more genes during chitin metabolism compared to that of glucose, the detected protein-mRNA correlation was low. As one of the first studies of its kind, the involvement of over 350 unique enzymes and 570 unique genes in the catabolic chitin response of a Gram-negative bacterium could be identified through a three-way systems biology approach. Based on the cumulative data, a holistic model for the chitinolytic machinery of Jeongeupia spp. is proposed.

Polyethylene glycol and chitosan functionalized manganese oxide nanoparticles for antimicrobial and anticancer activities

Biocompatible polymer-functionalized magnetic nanoparticles could offer promising applications in biomedical sciences. We fabricated polymer functionalized tri-manganese tetra oxide (Mn₃O₄) nanoparticles with the co-precipitation method and an octahedral crystal structure having a crystallite size of 10-17 nm was identified via XRD analyses. The SEM graph depicted the non-uniform and smooth surface of PEG-functionalized Mn₃O₄ NPs as compared to Mn₃O₄ and chitosan-coated Mn₃O₄ NPs. Elemental composition in the prepared sample was examined by EDX analysis. Various modes such as MnO, MnOH, OH, symmetric, and anti-symmetric of CH₂ attached to the spectrum of Mn₃O₄ NPs were observed with FTIR analysis. The magnetization factor decreased and increase the coreacivity and retentivity of surface functionalized Mn₃O₄-NPs was calculated via VSM analysis. In-vitro bioassay, antibacterial activity was tested against Escherichiacoli, Bacillus cereus, and anti-fungal activities against two Fusarium strains indicated clear antimicrobial activities. The MTT assay to examine the anticancer activity against the MCF-7 cancer cell line was performed and the T₁ MRI contrast agent demonstrated that PEG-coated Mn₃O₄ NPs exhibited anti-cancer activities. We propose that surface-functionalized magnetic NPs used for the treatment of cancer by using a remote controlled process of hyperthermia therapy.

Extraction, quantification, characterization, and application in food packaging of chitin and chitosan from mushroom: A review

The application of chitin in food systems is limited by its insolubility in some common solvents and poor degradability. Hence, it is deacetylated to obtain chitosan, an industrially important derivative with excellent biological properties. Fungal-sourced chitosan is gaining prominence and industrial attraction because of its superior functional and biological properties, and vegan appeal. Further, the absence of such compounds as tropomyosin, myosin light chain, and arginine kinase, which are known to trigger allergic reactions, gives it an edge over marine-sourced chitosan in food and pharmaceutical applications. Mushrooms are macro-fungi with a significant content of chitin, with many authors reporting the highest content to be in the mushroom stalks. This indicates a great potential for the valorisation of a hitherto waste product. Hence, this review was written to provide a global summary of literature reports on the extraction and yield of chitin and chitosan from different fruiting parts of some species of mushroom, different methods used to quantify extracted chitin, as well as physicochemical properties of chitin and chitosan from some mushroom species are presented. Critical comparisons of reports on chitin and chitosan from mushrooms and other sources are made. This report concludes with an exposition of the potential application of mushroom-sourced chitosan for food packaging application. The reports from this review provide a very positive outlook regarding the use of mushrooms as a sustainable source of chitin and chitosan and the subsequent application of chitosan as a functional component in food packaging.

Recent Advances in Chitosan-Based Applications-A Review

Chitosan derived from chitin gas gathered much interest as a biopolymer due to its known and possible broad applications. Chitin is a nitrogen-enriched polymer abundantly present in the exoskeletons of arthropods, cell walls of fungi, green algae, and microorganisms, radulae and beaks of molluscs and cephalopods, etc. Chitosan is a promising candidate for a wide variety of applications due to its macromolecular structure and its unique biological and physiological properties, including solubility, biocompatibility, biodegradability, and reactivity. Chitosan and its derivatives have been known to be applicable in medicine, pharmaceuticals, food, cosmetics, agriculture, the textile and paper industries, the energy industry, and industrial sustainability. More specifically, their use in drug delivery, dentistry, ophthalmology, wound dressing, cell encapsulation, bioimaging, tissue engineering, food packaging, gelling and coating, food additives and preservatives, active biopolymeric nanofilms, nutraceuticals, skin and hair care, preventing abiotic stress in flora, increasing water availability in plants, controlled release fertilizers, dye-sensitised solar cells, wastewater and sludge treatment, and metal extraction. The merits and demerits associated with the use of chitosan derivatives in the above applications are elucidated, and finally, the key challenges and future perspectives are discussed in detail.

Chitin/chitosan extraction from shrimp shell waste by a completely biotechnological process

Two lactic bacteria were used in sequential co-cultures to demineralize (DM) and deproteinize (DP) shrimp shells (SS) to obtain chitin. During the first 24 h, Lactobacillus delbrueckii performed the DM in a minimal medium containing 100 g/L SS and 50 g/L glucose. Then, three different conditions were assayed to complete DM and perform the DP stage: 1) Bifidobacterium lactis was added with 35 g/L of glucose (Ld-G → Bl-G); 2) only B. lactis was added (Ld-G → Bl); and 3) a 35 g/L pulse of glucose was added, and at 48 h, B. lactis was inoculated (Ld-G → G → Bl). The highest DM (98.63 %) and DP (88 %) were obtained using a glucose pulse in the DM step and controlling the pH value above 6.0 in the DP step. Finally, a deacetylases cocktail produced by Aspergillus niger catalyzed the deacetylation of the resulting chitin. The chitosan samples had a deacetylation degree higher than 78 % and a solubility of 25 % in 1.0 N acetic acid. The deacetylation yield was 74 % after a mild chemical treatment, with a molecular weight of 71.31 KDa. This work reports an entirely biological process to get chitin and chitosan from SS with high yields.

Design and experimental study on closed-loop process of preparing chitosan from crab shells

The purpose of this article is to design a green and comprehensive utilization process for preparing chitosan from crab shells. Glutamate acid was used as a decalcifying agent for crab shells, and the mixed solution of potassium hydroxide/isopropanol was used for deproteinization and deacetylation to prepare chitosan. Glutamic acid and isopropanol could be recovered for recycling. At the same time, calcium carbonate and protein in crab shells were converted into calcium hydrogen phosphate and compound fertilizer containing nitrogen, phosphorus, and potassium, respectively. The prepared chitosan was characterized by Fourier-transform infrared (FT-IR), differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM), and its deacetylation degree and viscosity average molecular weight were 88.7% ± 0.68% and 792.1 ± 10.82 kDa, respectively. The recoveries of glutamic acid and isopropanol were 95.56% ± 1.39% and 88.14% ± 1.13%, respectively. The prepared chitosan has large molecular weight and deacetylation degree, controllable production cost, comprehensive utilization of crab shell components, and greatly reduced waste emissions.

Management of Brain Cancer and Neurodegenerative Disorders with Polymer-Based Nanoparticles as a Biocompatible Platform

The blood-brain barrier (BBB) serves as a protective barrier for the central nervous system (CNS) against drugs that enter the bloodstream. The BBB is a key clinical barrier in the treatment of CNS illnesses because it restricts drug entry into the brain. To bypass this barrier and release relevant drugs into the brain matrix, nanotechnology-based delivery systems have been developed. Given the unstable nature of NPs, an appropriate amount of a biocompatible polymer coating on NPs is thought to have a key role in reducing cellular cytotoxicity while also boosting stability. Human serum albumin (HSA), poly (lactic-co-glycolic acid) (PLGA), Polylactide (PLA), poly (alkyl cyanoacrylate) (PACA), gelatin, and chitosan are only a few of the significant polymers mentioned. In this review article, we categorized polymer-coated nanoparticles from basic to complex drug delivery systems and discussed their application as novel drug carriers to the brain.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

High content chitosan-based materials with high performance properties

Chitosan is a valuable biopolymer with a great potential to be used in the design of sustainable materials. Its use typically requires converting the solid powder into a quite dilute solution by disrupting the hydrogen bonding between primary amine and hydroxyl groups. In this work we show that chitosan can be reacted with a tris-aromatic tris-epoxy monomer, generating thermoset materials. The design of the new structures adopted a strategy where the chitosan was mixed in its solid form, to avoid the use of solvents and additional processing steps. A combined polymerization mechanism was proposed, including growth chain polymerization and polyaddition. The obtained materials containing different epoxy/chitosan weight percentage ratios show outstanding properties: high glass transition ~230 °C, high Young's modulus ~2116 and 1716 MPa, tensile strength of ~35 MPa and T_5% ~ 300 °C.

Hydrogen sulfide-sensitive Chitosan-SS-Levofloxacin micelles with a high drug content: Facile synthesis and targeted Salmonella infection therapy

The delivery system of antibiotics plays an important role in increasing the drug efficacy and reducing the risks of off-target toxicities and antibiotic resistance. The pathophysiology of bacterial infections is similar to that of tumor tissues, but only a few delivery systems have been able to target and release antibiotics on demand. Herein, we designed and developed a robust Chitosan-SS-Levofloxacin (CS-SS-LF) micelles for targeted antibiotic delivery, in which disulfide bond can be reduced by hydrogen sulfide (H₂S), a typical product of Salmonella, and subsequently released antibiotic to eradicate Salmonella infection. CS-SS-LF micelles showed uniform size and sharp response to H₂S. Compared with levofloxacin alone, these micelles possessed a better capacity in disrupting Salmonella biofilms and reducing bacterial burden in organs. The H2S-sensitive CS-SS-LF micelles might enable a new way to address bacterial infections.

Cockroaches: a potential source of novel bioactive molecule(s) for the benefit of human health

Cockroaches are one of the hardiest insects that have survived on this planet for millions of years. They thrive in unhygienic environments, are able to survive without food for up to 30 days, without air for around 45 min and being submerged under water for 30 min. Cockroaches are omnivorous and feed on a variety of foods, including cellulose and plastic, to name a few. It is intriguing that cockroaches are able to endure and flourish under conditions that are harmful to Homo sapiens. Given the importance of the gut microbiome on its' host physiology, we postulate that the cockroach gut microbiome and/or its metabolites, may be contributing to their "hardiness", which should be utilized for the discovery of biologically active molecules for the benefit of human health. Herein, we discuss the biology, diet/habitat of cockroaches, composition of gut microbiome, cellular senescence, and resistance to infectious diseases and cancer. Furthermore, current knowledge of the genome and epigenome of these remarkable species is considered. Being one of the most successful and diverse insects, as well as their extensive use in traditional and Chinese medicine, the lysates/extracts and gut microbial metabolites of cockroaches may offer a worthy resource for novel bioactive molecule(s) of therapeutic potential for the benefit of human health and may be potentially used as probiotics.

Morphological and structural characterization of chitin as a substrate for the screening, production, and molecular characterization of chitinase by Bacillus velezensis

The processing of shellfishery industrial wastes is gaining much interest in recent times due to the presence of valuable components. Chitin is one of the valuable components and is insoluble in most common solvents including water. In this study, a novel gram-positive bacterial strain capable of solubilizing chitin was screened from a prawn shell dumping yard. The chitinolytic activity of the isolated strain was observed through the zone of hydrolysis plate assay. The hyper-producing isolate was identified as Bacillus velezensis through the 16S rRNA sequencing technique. The structural and morphological characterization of raw and colloidal chitin preparation was carried out using FTIR, XRD, and SEM analysis. The residual protein and mineral content, degree of polymerization, and degree of acetylation were reported for both raw and colloidal chitin preparations. There was a linear increase in the chitinase activity with an increase in the colloidal chitin concentration. The maximum activity of chitinase was observed as 38.98 U/mL for the initial colloidal chitin concentration of 1.5%. Supplement of additional carbon sources, viz., glucose and maltose, did not improve the production of chitinase and resulted in a diauxic growth pattern. The maximum chitinase activity was observed to be 33.10 and 30.28 U/mL in the colloidal chitin-containing medium with and without glucose as a secondary carbon source, respectively. Interestingly, the addition of complex nitrogen sources has increased the production of chitinase. A 1.95- and 2.14-fold increase in the enzyme activity was observed with peptone and yeast extract, respectively. The chitinase was confirmed using SDS-PAGE, native PAGE, and zymograms. The optimum pH and temperature for chitinase enzyme activity were found to be 7.0 and 44 °C, respectively.

Recent advances in biopolymer-based advanced oxidation processes for dye removal applications: A review

Over the past few years, synthetic dye-contaminated wastewater has attracted considerable global attention due to the low biodegradability and the ability of organic dyes to persist and remain toxic, causing numerous health and environmental concerns. As a result of the recalcitrant nature of those complex organic dyes, the remediation of wastewater using conventional wastewater treatment techniques is becoming increasingly challenging. In recent years, advanced oxidation processes (AOPs) have emerged as a potential alternative to treat organic dyestuffs discharged from industries. The most widely employed AOPs include photocatalysis, ozonation, Fenton oxidation, electrochemical oxidation, catalytic heterogeneous oxidation, and ultrasound irradiation. These processes involve the generation of highly reactive radicals to oxidize organic dyes into innocuous minerals. However, many conventional AOPs suffer from several setbacks, including the high cost, high consumption of reagents and substrates, self-agglomeration of catalysts, limited reusability, and the requirement of light, ultrasound, or electricity. Therefore, there has been significant interest in improving the performance of conventional AOPs using biopolymers and heterogeneous catalysts such as metal oxide nanoparticles (MONPs). Biopolymers have been widely considered in developing green, sustainable, eco-friendly, and low-cost AOP-based dye removal technologies. They inherit intriguing properties like biodegradability, renewability, nontoxicity, relative abundance, and sorption. In addition, the immobilization of catalysts on biopolymer supports has been proven to possess excellent catalytic activity and turnover numbers. The current review provides comprehensive coverage of different AOPs and how efficiently biopolymers, including cellulose, chitin, chitosan, alginate, gelatin, guar gum, keratin, silk fibroin, zein, albumin, lignin, and starch, have been integrated with heterogeneous AOPs in dye removal applications. This review also discusses the general degradation mechanisms of AOPs, applications of biopolymers in AOPs and the roles of biopolymers in AOPs-based dye removal processes. Furthermore, key challenges and future perspectives of biopolymer-based AOPs have also been highlighted.

Shrimp-waste based dispersant as oil spill treating agent: Biodegradation of dispersant and dispersed oil

The emerging demand for the enhancement of biodegradation of persistent organic pollutants from marine oil spills using oil-treating agents to minimize the environmental impacts promotes the development of green dispersants. Shrimp waste is a potential raw material to generate green dispersants. The biodegradability of dispersed oil and dispersants themselves are key factors for the national consideration of the approval, stockpile, and usage of dispersants. However, it is unknown whether shrimp-waste-based dispersant (SWD) has high bioavailability or facilitates the biodegradation of dispersed oil. In this study, we tackled the biodegradation of oil dispersed by a purified SWD. Furthermore, the SWD biodegradability was evaluated by exploring the degradation genes via metagenomic sequencing, analyzing the enzymatic activities for dispersant biodegradation by molecular docking, and discussing the SWD toxicity. We discovered that the SWD facilitated the biodegradation of two crude oils (Alaska North Slope and Marine Fuel-No.6). The metagenomic analysis with molecular docking showed that fresh seawater had feasible enzymes to degrade the SWD to safety components. Additionally, the SWD was low toxic and high bioactive. The findings helped confirm that the purified SWD is an effective and eco-sustainable marine oil spill treating agent and tracked the biodegradation of dispersed oil and the SWD.

Chitosan and its derivatives as polymeric anti-viral therapeutics and potential anti-SARS-CoV-2 nanomedicine

The coronavirus pandemic, COVID-19 has a global impact on the lives and livelihoods of people. It is characterized by a widespread infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where infected patients may develop serious medical complications or even face death. Development of therapeutic is essential to reduce the morbidity and mortality of infected patients. Chitosan is a versatile biomaterial in nanomedicine and exhibits anti-microbial, anti-cancer and immunomodulatory properties. This review highlights the progress in chitosan design and application pertaining to the anti-viral effects of chitosan and chitosan derivatives (hydroxypropyl trimethylammonium, sulfate, carboxymethyl, bromine, sialylglycopolymer, peptide and phosphonium conjugates) as a function of molecular weight, degree of deacetylation, type of substituents and their degree and site of substitution. The physicochemical attributes of these polymeric therapeutics are identified against the possibility of processing them into nanomedicine which can confer a higher level of anti-viral efficacy. The designs of chitosan for the purpose of targeting SARS-CoV-2, as well as the ever-evolving strains of viruses with a broad spectrum anti-viral activity to meet pandemic preparedness at the early stages of outbreak are discussed.

A comprehensive review of food gels: formation mechanisms, functions, applications, and challenges

Gels refer to the soft and flexible macromolecular polymeric materials retaining a large amount of water or biofluids in their three-dimensional network structure. Gels have attracted increasing interest in the food discipline, especially proteins and polysaccharides, due to their good biocompatibility, biodegradability, nutritional properties, and edibility. With the advancement of living standards, people's demand for nutritious, safe, reliable, and functionally diverse food and even personalized food has increased. As a result, gels exhibiting unique advantages in food application will be of great significance. However, a comprehensive review of functional hydrogels as food gels is still lacking. Here, we comprehensively review the gel-forming mechanisms of food gels and systematically classify them. Moreover, the potential of hydrogels as functional foods in different types of food areas is summarized, with a special focus on their applications in food packaging, satiating gels, nutrient delivery systems, food coloring adsorption, and food safety monitoring. Additionally, the key scientific issues for future food gel research, with specific reference to future novel food designs, mechanisms between food components and matrices, food gel-human interactions, and food gel safety, are discussed. Finally, the future directions of hydrogels for food science and technology are summarized.

Chitin Isolation and Chitosan Production from House Crickets (Acheta domesticus) by Environmentally Friendly Methods

Alternative methods were evaluated for chitin isolation from Acheta domesticus. Chemical demineralization was compared to fermentation with Lactococcus lactis, citric acid treatment, and microwave treatment, leading to a degree of demineralization of 91.1 ± 0.3, 97.3 ± 0.8, 70.5 ± 3.5, and 85.8 ± 1.3%, respectively. Fermentation with Bacillus subtilis, a deep eutectic solvent, and enzymatic digestion were tested for chitin isolation, generating materials with less than half the chitin content when compared to alkaline deproteinization. Chitosan was produced on a large scale by deacetylation of the chitinous material obtained from two selected processes: the chemical treatment and an alternative process combining L. lactis fermentation with bromelain deproteinization. The chemical and alternative processes resulted in similar chitosan content (81.9 and 88.0%), antioxidant activity (59 and 49%), and degree of deacetylation (66.6 and 62.9%), respectively. The chitosan products had comparable physical properties. Therefore, the alternative process is appropriate to replace the chemical process of chitin isolation for industrial applications.

Chitosan: Sources, Processing and Modification Techniques

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is derived from chitin. Chitin is found in cell walls of crustaceans, fungi, insects and in some algae, microorganisms, and some invertebrate animals. Chitosan is emerging as a very important raw material for the synthesis of a wide range of products used for food, medical, pharmaceutical, health care, agriculture, industry, and environmental pollution protection. This review, in line with the focus of this special issue, provides the reader with (1) an overview on different sources of chitin, (2) advances in techniques used to extract chitin and converting it into chitosan, (3) the importance of the inherent characteristics of the chitosan from different sources that makes them suitable for specific applications and, finally, (4) briefly summarizes ways of tailoring chitosan for specific applications. The review also presents the influence of the degree of acetylation (DA) and degree of deacetylation (DDA), molecular weight (M_w) on the physicochemical and biological properties of chitosan, acid-base behavior, biodegradability, solubility, reactivity, among many other properties that determine processability and suitability for specific applications. This is intended to help guide researchers select the right chitosan raw material for their specific applications.