Structural characterization and properties of konjac glucomannan/curdlan blend films

The Use of Novel Colorimetric Films to Monitor the Freshness of Pork, Utilizing Konjac Glucomannan With Curcumin/Alizarin

In this study, different proportions of curcumin (CUR) and alizarin (ALI) were added to konjac glucomannan (KG)/ polyvinyl alcohol (PVA) to prepare an active intelligent packaging film and evaluate its potential to indicate pork freshness. The mixed indicator had a richer color hierarchy in the buffer solution with pH = 2-12. The surface of the KG-2C2A and KG-1C3A films is smoother and has fewer cross-section faults. With the increase of CUR content in the film, the crystal structure becomes more prominent, leading to poor compatibility with KG. The WAC of KG-3C1A and KG-1C3A films was significantly higher than that of the other groups, and they had better hydrophobicity. With the increase of CUR content in the films, the thermal stability of the films was enhanced, and the KG-C films showed the highest thermal stability. Among them, the KG-2A2C and KG-1C3A films showed the most significant color change during pork spoiling and could be used to monitor the freshness of pork. As a pH colorimetric indicator, CUR and ALI-coated KG films might be of great potential in fresh meat monitoring.

Potential for curdlan recovery from aerobic granular sludge wastewater treatment systems - A review

The aerobic granular sludge (AGS) biotechnology has been explored for wastewater treatment for over two decades. AGS is gaining increased interest due to its enhanced treatment performance ability and the potential for resource recovery from AGS-based wastewater treatment systems. Resource recovery from AGS is a promising approach to sustainable wastewater treatment and attaining a circular economy in the wastewater management industry. Currently, research is at an advanced stage on recovering value-added resources such as phosphorus, polyhydroxyalkanoates, alginate-like exopolysaccharides, and tryptophan from waste aerobic granules. Recently, other value-added resources, including curdlan, have been identified in the aerobic granule matrix, and this may increase the sustainability of biotechnology in the wastewater industry. This paper provides an overview of AGS resource recovery potential. In particular, the potential for enhanced curdlan biosynthesis in the granule matrix and its recovery from AGS wastewater treatment systems is outlined.

Composite hydrogels fabricated from konjac glucomannan and gellan gum: Rheological characterization and their potential application in sustainable agriculture

In this study, konjac glucomannan (KG) was incorporated in high acyl gellan (HAG) and low acyl gellan (LAG) hydrogels in different ratios. The addition of KG increased pseudoplasticity and thermal hysteresis values of the hydrogels. Improvement in elasticity and water holding capacity (WHC) was observed in KG-LAG hydrogels. The highest WHC (98.5 %) was observed for 1K1H (KG:HAG = 1:1) and 3K7L (KG:LAG = 3:7) hydrogels. The crystallinity of the composite hydrogels was lower than hydrogels prepared from individual biopolymers. The hydrogels exhibited a rough surface with minute pores in the cross-section, due to the aggregation of glucomannan on the gellan network in the composite hydrogels. While HAG and 1K1H hydrogels exhibited greater swelling at low pH (3.0), LAG and 3K7L exhibited greater swelling at high pH (11.0). At pH 7.0, the hydrogels exhibited swelling indices >300 %. Incorporation of 1K1H hydrogel at 10 % (w/w) in sandy loamy soil under semi-arid conditions increased the germination of fenugreek microgreens from 60 % to 80 % on the 15th day. Furthermore, the moisture evaporation rate of the soil reduced from 35 % to <15 %, positively impacting the physicochemical properties of the microgreens. The composite hydrogels were successful in achieving a controlled release of phosphate fertilizer.

Gellan Gum as a Unique Microbial Polysaccharide: Its Characteristics, Synthesis, and Current Application Trends

Gellan gum (GG) is a linear, negatively charged exopolysaccharide that is biodegradable and non-toxic. When metallic ions are present, a hard and transparent gel is produced, which remains stable at a low pH. It exhibits high water solubility, can be easily bio-fabricated, demonstrates excellent film/hydrogel formation, is biodegradable, and shows biocompatibility. These characteristics render GG a suitable option for use in food, biomedical, and cosmetic fields. Thus, this review paper offers a concise summary of microbial polysaccharides. Moreover, an in-depth investigation of trends in different facets of GG, such as biosynthesis, chemical composition, and physical and chemical properties, is emphasized. In addition, this paper highlights the process of extracting and purifying GG. Furthermore, an in-depth discussion of the advantages and disadvantages of GG concerning other polysaccharides is presented. Moreover, the utilization of GG across different industries, such as food, medicine, pharmaceuticals, cosmetics, etc., is thoroughly examined and will greatly benefit individuals involved in this field who are seeking fresh opportunities for innovative projects in the future.

A novel curdlan/methyl cellulose/walnut green husk polyphenol edible composite film for walnut packaging

In this study, polyphenols were extracted from walnut green husk, an agricultural waste, and were incorporated into curdlan (CD) and methyl cellulose (MC) to create a novel edible composite film. For structural character, the film matrix was tightly bound primarily by non-covalent bonds and the addition of walnut green husk polyphenols (WGHP) significantly reduced the surface roughness of the composite film. For mechanical properties, the addition of WGHP improve the flexibility of films, and it significantly improved the barrier ability of ultraviolet rays and water-vapor. Furthermore, the incorporation of WGHP to the CD-MC film resulted in enhanced antioxidant and antibacterial effects, which effectively retards lipid oxidation in fried walnuts. Consequently, the fabricated CD-MC-WGHP composite film bears immense potential for use in food preservation applications, particularly in extending the shelf life of fried walnuts.

Properties of konjac glucomannan/curdlan-based emulsion films incorporating camellia oil and the preservation effect as coatings on 'Kyoho' grapes

The strategy of emulsion coating was used for grape preservation. Camellia oil (CO) was incorporated with KGM/curdlan (KC) to fabricate KC-CO emulsion systems. KC-CO emulsions were analyzed by droplet size distribution and confocal laser scanning microscopy (CLSM), and KC-CO films were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), mechanical properties, dissolution, gas permeability, water contact angle (WCA). KC-CO coating was used for preservation of 'Kyoho' grapes. The results indicated that the addition of CO had a positive effect on KC system. CO could form a uniform emulsion with KC, and the droplets were evenly dispersed in the KC matrix. KC-CO films displayed a continuous microstructure, and elongation at break (EAB) was improved, while tensile strength decreased. The dissolution, water vapor permeability (WVP), and WCA were significantly enhanced, while the permeability of oxygen and carbon dioxide exhibited no advantage compared with KC film. KC-CO-10 possessed optimal properties and was selected as an emulsion coating for preservation. The results suggested that KC-CO-10 significantly maintained the appearance, total solid and acid content of 'Kyoho' grapes, and delayed the weight loss and firmness decrease. This study contributed to the understanding of polysaccharide-lipid emulsion system and the applications.

High-moisture extrusion of curdlan: Texture and structure

High-moisture extrusion is a promising thermomechanical technology extensively employed in manufacturing fibrous meat analogues from plant-based proteins, garnering considerable research attention. However, polysaccharide-based extrusion has been rarely explored. The present study investigates the effects of varying extruder barrel temperatures (130 °C-200 °C) on the texture and structure of curdlan extrudates, and highlights the formation mechanism. Results showed that the single chain of curdlan aggregates to form triple-helix chains upon extrusion, consequently enhancing the crystallinity, particularly at 170 °C. The hardness, chewiness, and mechanical properties improved with increasing barrel temperature. Moreover, barrel temperatures affected the macrostructure, the extrudates maintained intact morphologies except at 160 °C due to the melting of curdlan gel as confirmed by the differential scanning calorimetry thermogram. Microstructural analysis revealed that curdlan extrudates transited through three phases: original gel (130 °C, 140 °C, and 150 °C), transition state (160 °C), and regenerated gel (170 °C, 180 °C, 190 °C, and 200 °C). The steady state of regenerated gel (170 °C) exhibited higher crystallinity and smaller fractal dimension, resulting in a more compact and crosslinked gel network. This study elucidates the structure transition of curdlan gel at extremely high temperatures, offering valuable technical insights for developing theories and methods with respect to polysaccharide-based extrusion that may find applications in food-related fields.

Characterizations of Water-Soluble Chitosan/Curdlan Edible Coatings and the Inhibitory Effect on Postharvest Pathogenic Fungi

This study focused on developing a composite coating comprising water-soluble chitosan (CTS) and curdlan (CUR). Cherry tomatoes served as the test material for assessing the preservative efficacy of these coatings. The incorporation of CUR markedly enhanced the coating's surface properties, refined its molecular structure, and improved its tensile strength and elongation at break. Additionally, the coating demonstrated enhanced permeability to water vapor, oxygen, and carbon dioxide and improved light transmission. The storage experiment, conducted at 25 ± 1 °C with a relative humidity of approximately 92% over 10 days, revealed that the CTS/CUR composite coating at a 1:1 ratio significantly outperformed the individual CTS or CUR coating and uncoated samples in maintaining the quality of postharvest cherry tomatoes. The 1:1 CTS/CUR composite coating demonstrated superior preservative effects. This study suggested that water-soluble chitosan/curdlan composite coatings have considerable potential for use in the preservation of postharvest fruits and vegetables.

Comprehensive investigation into the effects of yeast dietary fiber and temperature on konjac glucomannan/kappa-carrageenan for the development of fat analogs

In this study, yeast dietary fiber (YDF) was incorporated into konjac glucomannan/kappa-carrageenan (KGM/κ-KC) for the development of fat analogs, and the impact of YDF on the gelation properties and behavior of KGM/κ-KC composite gels was assessed. YDF improved the composite gel whiteness value, and affected the mechanical properties of the composite gel, especially enhancing its hardness, and decreasing its chewiness, elasticity, and gel strength, making it more similar to porcine back fat. When the yeast dietary fiber content was 0.033 g/mL and the heating temperature was 80 °C (T80-2), the textural properties of the composite gel were closest to porcine back fat. The frequency sweep results suggested that YDF incorporation led to enhancement of the intermolecular interaction and intermixing and interaction among more easily at higher processing temperatures (80 °C and 90 °C). By scanning electron microscopy, the fatty surface of porcine back fat was flat and covered with a large amount of oil, while KGM/κ-KC/YDF composite gels developed a dense, stacked network structure. YDF caused more fragmented, folded, and uneven structures to emerge. Overall, YDF could influence the gel behavior of KGM/κ-KC composite gels, and change their colors and mechanical properties. This work could serve as a guide for preparing fat analogs with KGM/κ-KC composite gels.

Perspectives of nanofibrous wound dressings based on glucans and galactans - A review

Wound healing is a complex and dynamic process that needs an appropriate environment to overcome infection and inflammation to progress well. Wounds lead to morbidity, mortality, and a significant economic burden, often due to the non-availability of suitable treatments. Hence, this field has lured the attention of researchers and pharmaceutical industries for decades. As a result, the global wound care market is expected to be 27.8 billion USD by 2026 from 19.3 billion USD in 2021, at a compound annual growth rate (CAGR) of 7.6 %. Wound dressings have emerged as an effective treatment to maintain moisture, protect from pathogens, and impede wound healing. However, synthetic polymer-based dressings fail to comprehensively address optimal and quick regeneration requirements. Natural polymers like glucan and galactan-based carbohydrate dressings have received much attention due to their inherent biocompatibility, biodegradability, inexpensiveness, and natural abundance. Also, nanofibrous mesh supports better proliferation and migration of fibroblasts because of their large surface area and similarity to the extracellular matrix (ECM). Thus, nanostructured dressings derived from glucans and galactans (i.e., chitosan, agar/agarose, pullulan, curdlan, carrageenan, etc.) can overcome the limitations associated with traditional wound dressings. However, they require further development pertaining to the wireless determination of wound bed status and its clinical assessment. The present review intends to provide insight into such carbohydrate-based nanofibrous dressings and their prospects, along with some clinical case studies.

Characterizations of konjac glucomannan/curdlan edible coatings and the preservation effect on cherry tomatoes

In this study, konjac glucomannan (KGM) and curdlan were used to fabricate composite coating (KC). The coating solutions were investigated using a rheological method, and the coatings were characterized by water solubility tests, water vapor permeability (WVP), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The preservation effect of KC coating on cherry tomatoes stored at room temperature was determined. Results indicated that the curdlan addition can adjust the hydrophilicity/hydrophobicity of KGM coatings. Curdlan addition enhanced intermolecular entanglement and film-forming property. Increasing curdlan content in KC coatings significantly decreased the moisture content, dissolution and swelling ratio, and WVP. The KGM-curdlan composites behaved as high-performance coatings with good compatibility and uniformity. The K₃C₂ coating showed the best uniformity, water barrier, and thermal stability. The application of K₃C₂ coating significantly reduced the weight loss, decay loss, and delayed the decreases of firmness, soluble solids, total acid, and VC contents of cherry tomatoes. The KGM/curdlan edible coatings have promising potential for prolonging the shelf life of cherry tomatoes and applications in fruits preservation in the future.

The alleviative effect of curdlan on the quality deterioration of konjac glucomannan thermo-irreversible gels after commercial sterilization at 121 °C

This work employed different curdlan concentrations (0.00 %, 1.00 %, 1.50 %, 2.00 %, and 2.50 %) to alleviate the quality degradation of konjac glucomannan (KGM) gels after commercial sterilization at 121 °C for 15 min. The results showed that all levels of curdlan could retard the deterioration of KGM gels, with the best effect at 2.00 %. After commercial sterilization, incorporating curdlan into KGM gels greatly reduced the Tan σ (G"/ G'), total relaxation time and half-free water from 0.52, 89.85 ms and 98.26 % to 0.27, 38.48 ms and 21.42 %, respectively. Moreover, the addition of curdlan imparted a better texture to KGM gels, as reflected in the increase of hardness, springiness, water-holding capacity and whiteness value from 1400.85 g, 0.42, 87.92 % and 33.33 to 3461.68 g, 0.80, 96.50 % and 49.27, respectively. Furthermore, SEM images revealed that curdlan endowed KGM gels with a tighter structure and smaller pores, and the pore size distribution was reduced from 113.46 μm to17.91 μm, indicating a stronger interaction among molecules, as evidenced by XRD and FTIR results. KGM gels with curdlan possessed less proportion of complete crystallites and crystalline region. These findings suggested that curdlan can be the potently protectant for improving the quality of commercially sterilized KGM gel-based products.

Introduction of Curdlan Optimizes the Comprehensive Properties of Methyl Cellulose Films

The good oxygen barrier and hydrophobic properties of curdlan (CL) film might be suitable complements for MC film, and its similar glucose unit and thermal-gel character might endow the methyl cellulose (MC)/CL blended system with compatibility and good comprehensive properties. Thus, MC/CL blended films were developed. The effects of MC/CL blend ratios on the microstructures and physical properties of the blends were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), oxygen and water vapor permeability testing, dynamic mechanical analysis (DMA), light transmittance testing, tensile testing, hydrophilic property testing, and water solubility testing. The introduction of CL affected the molecular aggregation and crystallization of the MC molecules, suggesting MC-CL molecular interactions. The cross-sectional roughness of the MC/CL film increased with an increase in CL content, while the surface of the MC/CL 5:5 film was smoother than those of the MC/CL 7:3 and 3:7 films. Only one glass transition temperature, which was between that of the MC and CL films, was observed for the MC/CL 7:3 and MC/CL 5:5 films, indicating the good compatibility of the MC and CL molecules at these two blend ratios. The hydrophobicity and water insolubility increased with the CL content, which was due to the combined effects of more hydrophobic cavities in the CL triple-helix and increased surface roughness. Increased oxygen barrier properties with increasing CL content might be a combined effect of the increased hydrogen bonds and hydrophilic ektexines of the CL triple-helix. The elongations of the blended films were higher than those of the MC film, which might be related to its increased water content. The MC/CL 7:3 and MC/CL 5:5 films retained the good light transmittance and tensile strength of the MC film, which corresponded well to their good compatibility and might be due to the effects of the MC-CL molecular interactions and the relative smooth morphologies. MC/CL 5:5 showed improved water vapor barrier properties, which might be due to its smooth surface morphologies. This research offers new MC based films with improved properties and good compatibility, providing great potential for use as edible coatings, capsules, and packaging materials.

Thermal and Rheological Performances Evaluation of a Modified Biopolymer for Fracturing Fluid System

Developing an efficient fracturing fluid system is an enduring hot topic in the petrochemical industries, especially regarding the exploitation of limited oil. Biopolymers, especially polysaccharides (e.g., konjac gum, guar gum), are widely applied as fracturing fluids in fracturing as a result of their advantages. Herein, we propose an easy method of modifying konjac gum (KGM) using isopropanol, sodium hydroxide, and chloroacetic acid to obtain modified konjac glum (MKGM). The MKGM and KGM gels were also obtained by using the self-prepared organic titanium high-temperature stabilizer and organic borate cross-linker. The prepared MKGM was characterized by multiscale techniques, including attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and rheology properties. The ATR-FTIR results showed that the etherification modification reaction occurred as designed. The XRD results showed that the regularity of KGM was destroyed after modification. The TGA and DSC results showed that the thermal stability improved. Rheology measurements illustrated that the temperature and shear resistance of MKGM were better than those of KGM. The MKGM gel could be applied in fracturing fluid systems at a lower frequency through viscoelastic measurements.

Aggregation of konjac glucomannan by ethanol under low-alkali treatment

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Microstructure of KGM alcogels is distinct from that of normal KGM gels.

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Gel network of EAK_gel is more heterogeneous than that of EK_gel.

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Ethanol arranges the aggregation of deacetylated KGM chains.

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Both structure and function of KGM aggregates are altered by ethanol and alkali.

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Solvent quality deterioration drives the formation of low-alkali KGM alcogels.

Utilizing ethanol in konjac glucomannan (KGM) gelation has important food processing applications. Typically, ethanol positively impacts the formation of low-alkali KGM gels and dramatically changes their physical properties, but the role of ethanol on the aggregation of KGM chains and the resultant gelation is less well understood. This study presents the distinct microstructures of low-alkali KGM gels incorporating ethanol. The fibril diameter and mesh size were determined to be 262.3 ± 22.3 nm and 2.680 ± 0.035 μm in average, contributing to a higher degree of anisotropy of such a gel network. Ethanol favors intermolecular aggregation by increasing the R_g of small-sized aggregates to 2.10 nm. The FTIR and temperature-cycled rheological studies suggest there are hydrophobic interactions stabilizing the gel network with the assistance of hydrogen bonds. The spatial confinement of deacetylated KGM chains as the solvent quality deteriorates by incorporating ethanol may arrange the aggregation and induce the structural reorganization in gel formation.

Mechanochemical Effect on Controlled Drug Release of Konjac Glucomannan Matrix Tablets during Dry Grinding

To design a controlled drug release preparation based on a safe natural material, a Konjac glucomannan (KGM) mixture containing 16.0 w/w% calcium hydroxide (Ca(OH)₂) was ground in a planetary ball mill for 0–120 min. The mechanochemical effect on the physicochemical properties of the KGM ground product was investigated by Fourier-transform infrared spectroscopy (FT-IR), powder X-ray spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and drug release testing. The FT-IR spectra of the ground KGM indicated that the deacetylation reaction of KGM was accelerated in the Ca(OH)₂-containing sols by mechanochemical energy, and the degree of deacetylation of KGM was dependent on the grinding time. The time required for tablet disintegration of the KGM matrix tablets containing theophylline increased as the grinding time increased; therefore, drug release was sustained. The Higuchi plots of the matrix tablets obtained from KGM ground for 60–120 min exhibited good linearity because they maintained their gel matrix tablet shape during the release test. However, KGM tablets ground for 0–30 min exhibited nonlinear curves, which were caused by tablet disintegration. This suggests that drug release from the KGM matrix tablet can be freely controlled by the degree of mechanochemical treatment.

Structural characterization and antibacterial properties of konjac glucomannan/soluble green tea powder blend films for food packaging

Antimicrobial activity is a promising property for food packaging which could prolong the shelf life of food products. In this paper, the physicochemical and antimicrobial properties of konjac glucomannan (KGM)/soluble green tea powder (SGTP) edible films were firstly prepared and analyzed through light barrier properties, Fourier transform infrared spectroscopy (FT-IR), tensile strength (TS), X-ray diffraction (XRD), thermogravimetric analysis and scanning electron microscope (SEM). The results showed that appropriate addition of SGTP could improve the TS of composite films. With the increase of SGTP content, the transmittance of the films in the ultraviolet region decreased obviously, and the thermal stability was improved in a SGTP dependent manner. KGM/SGTP films present a fairly smooth and flat surface without any fracture when 0.5% SGTP was provided. The bacteriostatic test showed that the bacteriostatic performance of the composite films against Staphylococcus aureus and Escherichia coli was also significantly enhanced. When 1% SGTP was provided, the zones of inhibition for Escherichia coli and Staphyloccocus aureus reached to 13.45 ± 0.94 mm and 13.76 ± 0.92 mm, respectively. Overall, the KGM/SGTP films showed great potential as bioactive packaging materials to extend food shelf life.

Deacetylation enhances the properties of konjac glucomannan/agar composites

From a microstructural point of view, this work concerns how deacetylation improves the practical characteristics of deacetylated-konjac glucomannan/agar (DK/A) composite films. As disclosed by infrared spectroscopy and X-ray diffraction, the deacetylation of konjac glucomannan (KGM) enhanced the chain interactions in DK/A composites and suppressed the realignment of agar molecules into crystallites. The enhanced associations between acetyl-free regions of KGM and agar reduced the exposure of OH groups and thus increased the hydrophobicity of the composites. Besides, the partial removal of acetyl groups allowed shortened distances between chains; consequently, denser composite matrices emerged with lower water vapor permeability and higher tensile strength. Also, the KGM deacetylation increased the matrix flexibility and elongation at break for DK/A composites, associated with the hindered rearrangement of agar chains. Thus, altering the deacetylation degree of KGM may be an effective way to design KGM-based composites with improved hydrophobicity and mechanical performance.

Applications of Microbial Exopolysaccharides in the Food Industry

Exopolysaccharides (EPSs) are high molecular weight polysaccharides secreted by microorganisms in the surrounding environment. In addition to the favorable benefits of these compounds for microorganisms, including microbial cell protection, they are used in various food, pharmaceutical, and cosmetic industries. Investigating the functional and health-promoting characteristics of microbial EPS, identifying the isolation method of these valuable compounds, and their applications in the food industry are the objectives of this study. EPS are used in food industries as thickeners, gelling agents, viscosifiers, and film formers. The antioxidative, anticancer, prebiotic, and cholesterol-lowering effects of some of these compounds make it possible to use them in functional food production.

Investigation of the structural and physical properties, antioxidant and antimicrobial activity of konjac glucomannan/cellulose nanocrystal bionanocomposite films incorporated with phlorotannin from Sargassum

In this study, environmentally friendly bionanocomposite films were prepared by incorporating phlorotannins from Sargassum (PS) into konjac glucomannan (KGM)/cotton cellulose nanocrystals (CNC) composites. The effects of different concentrations of PS (5%, 9%, 13%, and 17%, w/w) on the microstructure, physical properties, antioxidant and antibacterial activities of the resultant bionanocomposite films were evaluated. The results of scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectra showed that PS was well compatible with the KGM/CNC composites matrix, which led to form a compact and uniform structure of the films. Thermogravimetric analysis and differential scanning calorimetry demonstrated that incorporating PS improved the heat stability of KGM/CNC bionanocomposite films. And addition of the appropriate amount of PS improved the mechanical and water-vapor barrier-related properties of the bionanocomposite film. For instance, with 9% PS, the tensile strength of the KGM/CNC/PS bionanocomposite film increased by 33.9%, and the water-vapor transmittance decreased by 41.67% compared to that of the KGM/CNC films. Moreover, the addition of PS endowed the KGM/CNC film with excellent antioxidant and antibacterial properties. Therefore, KGM/CNC/PS bionanocomposite films have great potential to be applicated as active packaging in the food packaging industry.

Rheological investigation of a versatile salecan/curdlan gel matrix

Hydrogel, as a three-dimensional material with high water content, has unique physicochemical and variable mechanical properties. Natural polysaccharide-based composite hydrogels are very popular within medical industry as these viscoelastic materials are non-toxic, biodegradable, bioabsorbable, and biocompatible. This research investigates the engineering of novel composite hydrogels from natural polysaccharides salecan and curdlan without any structural modification and chemical crosslinking. The scanning electron microscopy, Fourier transform infrared spectroscopy and various rheological methods were employed to investigate the morphology, molecular interaction, and flow behavior of the samples respectively. The key rheological parameters were compared using the Power Law, Herschel-Bulkley and Arrhenius models. This is the first study reporting a novel composite hydrogel made from Salecan and Curdlan with ideal elasticity, enhanced thermostability, good injectability, self-recovery and other rheological properties that will pave the way for application in different fields.

Recent advances in the production of biomedical systems based on polyhydroxyalkanoates and exopolysaccharides

In recent years, growing attention has been devoted to naturally occurring biological macromolecules and their ensuing application in agriculture, cosmetics, food and pharmaceutical industries. They inherently have antigenicity, low immunogenicity, excellent biocompatibility and cytocompatibility, which are ideal properties for the design of biomedical devices, especially for the controlled delivery of active ingredients in the most diverse contexts. Furthermore, these properties can be modulated by chemical modification via the incorporation of other (macro)molecules in a random or controlled way, aiming at improving their functionality for each specific application. Among the wide variety of natural polymers, microbial polyhydroxyalkanoates (PHAs) and exopolysaccharides (EPS) are often considered for the development of original biomaterials due to their unique physicochemical and biological features. Here, we aim to fullfil a gap on the present associated literature, bringing an up-to-date overview of ongoing research strategies that make use of PHAs (poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxyoctanoate), poly(3-hydroxypropionate), poly (3-hydroxyhexanoate-co-3-hydroxyoctanoate), and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate)) and EPS (bacterial cellulose, alginates, curdlan, pullulan, xanthan gum, dextran, hyaluronan, and schizophyllan) as sources of interesting and versatile biomaterials. For the first time, a monograph addressing the properties, pros and cons, status, challenges, and recent progresses regarding the application of these two important classes of biopolymers in biomedicine is presented.

Preparation and characterization of curdlan/nanocellulose blended film and its application to chilled meat preservation

In this study, to improve the mechanical and thermal properties of curdlan film, a curdlan/nanocellulose (NC) blended film was prepared and characterized for the first time. NC was successfully prepared from microcrystalline cellulose (MCC) with NaOH/urea treatment. The particle size of NC was observed to be 70-140 nm by cryo-electron microscope (cryo-EM). The blended film was prepared by adding the NC to curdlan solution. The tensile strength (TS) of the blended film reached the maximum value of 38.6 MPa, and the elongation at break (EB) was 40%. The DSC curve showed that the heat absorption peak of the film was 240 °C, indicating that the blended film has good temperature stability. Additionally, some other film properties were also improved, including gas barrier properties and transparency. Obvious morphological and molecular differences between the blended film and the pure curdlan film were discovered by SEM and FTIR analysis. Finally, the blended film was used for the preservation of chilled meat and extended the storage time of meat to 12 days. These results provided a theoretical basis for future application and development of biodegradable film.

Essential Oil-Containing Polysaccharide-Based Edible Films and Coatings for Food Security Applications

The wastage of food products is a major challenge for the food industry. In this regard, the use of edible films and coatings have gained much attention due to their ability to prevent the spoilage of the food products during handling, transport, and storage. This has effectively helped in extending the shelf-life of the food products. Among the various polymers, polysaccharides have been explored to develop edible films and coatings in the last decade. Such polymeric systems have shown great promise in microbial food safety applications. The inclusion of essential oils (EOs) within the polysaccharide matrices has further improved the functional properties of the edible films and coatings. The current review will discuss the different types of polysaccharides, EOs, methods of preparing edible films and coatings, and the characterization methods for the EO-loaded polysaccharide films. The mechanism of the antimicrobial activity of the EOs has also been discussed in brief.

Characteristics of karaya gum based films: Amelioration by inclusion of Schisandra chinensis oil and its oleogel in the film formulation

This research was focused to develop novel karaya gum films, modified by adding Schisandra chinensis oil and its oleogel. The films produced were assessed for physicochemical, mechanical, thermal and structural characteristics. Glass transition temperature (Tg) of control karaya gum films was recorded as 145.70 °C. Insignificant (p < 0.05) changes occurred in Tg of films in which oil was incorporated, irrespective of the concentration. However, Tg decreased significantly (p < 0.05) as oleogel was added to the karaya gum films and lowest Tg occurred for the KGOG3 films which contained highest concentration of oleogel. X-ray diffraction test depicted an obsolete amorphous behavior of control karaya gum film whereas some peaks appeared in other film samples. Scanning electron micrography (SEM) revealed a reduction in roughness and grainy morphology when oil or oleogel was added to the films. Addition of oil/oleogel enhanced the phenolic content and DPPH radical scavenging activity of the films.

Impact of heating and drying temperatures on the properties of konjac glucomannan/curdlan blend films

The impact of preparation conditions including heating temperature (from 60 °C to 90 °C) and drying temperatures (from 25 °C to 90 °C) on the properties of pure curdlan film and konjac glucomannan (KGM) and curdlan blend films were analyzed. Microstructure analysis indicated the KGM addition could significantly improve the relatively poor film-forming property of curdlan. FTIR and X-ray analysis showed that at high heating temperature 90 °C, molecular interaction might be enhanced in the films due to the stretched structure of curdlan and dissociation of curdlan bundles or triple-helix structure. This was supported by the changes in the mechanical property, surface hydrophobicity, moisture barrier, and moisture tolerance property. The impacts of drying temperature were some different for the curdlan film and KGM/curdlan blend film, and were explained from the molecular hydrophilicity-hydrophobicity, compactness of the films, curdlan conformation, and molecular interaction. This work guided biodegradable film production especially with curdlan added.

Fabrication of hydrophobic and high-strength packaging films based on the esterification modification of galactomannan

There is an increasing interest in substituting current packaging films with biologically-derived films without compromising mechanical properties and hydrophobicity. In this work, the esterified galactomannan (E-GM) films with good hydrophobicity, excellent oxygen barrier performance and high tensile mechanical strength were synthesized using anhydride esterification method prior to film formation. The hydrophobicity, mechanical properties, barrier properties, thermal stability and ultraviolet absorption of the prepared films were determined to fully investigate the features of galactomannan-based films. The results indicated that GM films can be successfully obtained by esterification. Compared to neat GM film, E-GM-1.5 film (acetic anhydride to GM of 1.5:1) achieved the highest degree of esterification (0.05), hydrophobicity (107°) and mechanical strength (92.0 MPa). In addition, the esterified GM films had lower toxicity for macrophages cells. The prepared E-GM films may provide more opportunities for further advancement and applications in the development of food packaging from natural resources.

Encapsulation of Grapefruit Essential Oil in Emulsion-Based Edible Film Prepared by Plum (Pruni Domesticae Semen) Seed Protein Isolate and Gum Acacia Conjugates

A dry-heated Maillard reaction was used to prepare plum seed protein isolate and gum acacia conjugates. Emulsion-based edible films (EBEF) were prepared by the encapsulation of grapefruit essential oil using conjugates solution as the continuous phase. The conjugates formed from 3 days of dry heating showed a significant improvement in emulsifying properties due to the unfolding of protein, as confirmed by structure analysis. The droplet size, electrical charge, and viscosity of emulsions increased with the increasing essential oil concentration, and all emulsions exhibited ‘gel’-like behavior. The water vapor barrier property, surface hydrophobicity, mechanical properties, and thermal stability of the films were improved as the essential oil content increased in the range of 1–4% due to enhancement in intermolecular interaction and compatibility, as well as a denser microstructure. Furthermore, all films exhibited an inhibitory effect against E. coli, while their radical scavenging activity depended on the release rate from films. The results obtained in this work confirmed that EBEF could be used as a novel food active packaging in the near future.