The influence of the addition of transglutaminase at different phase on the film and film forming characteristics of whey protein concentrate-carboxymethyl chitosan composite films

Effect of three polysaccharides with different charge characteristics on the properties of highland barley starch gel

Highland barley, a nutritious whole grain, faces limited market utilization due to the poor heating stability of its starch. The aim of this study was to investigate the effects of three differently charged ionic polysaccharides-guar gum (GG), xanthan gum (XG), and carboxymethyl chitosan (CMC)-on the gel properties of highland barley starch (HBS). GG and XG notably increased pasting viscosity, viscoelasticity, hardness, and strength of HBS gels. Conversely, CMC resulted in decreased gel properties. All three polysaccharides enhanced OH tensile vibration (3000-3800 cm-1), with GG and XG promoting denser honeycomb network structures and lower spin-spin relaxation time (T2), indicating improved structural integrity. In contrast, low concentrations of CMC led to disorder and loose structure. Hydrogen bonding and electrostatic interactions were the main forces by which polysaccharides influenced the properties of starch gels. This research contributes to enhancing the properties of HBS gel during heating and expanding its commercial applications. It also provides some insights to understand the interaction between different charged polysaccharides and starch.

Recent functionality developments of carboxymethyl chitosan as an active food packaging film material

In recent years, environmental concerns regarding the persistence of petroleum-based plastic food packaging have increased, prompting the exploration of biopolymer alternatives. Carboxymethyl chitosan (CMCS), a derivative of chitosan, exhibits superior water-soluble film properties, making it an ideal material for degradable food packaging applications. This study comprehensively examines the synthesis methods and properties of CMCS, with a particular emphasis on recent advancements in CMCS-based food packaging films. Various functionalized CMCS-based food packaging films, including coblended, nanoparticle composite, plant extract composite, and cross-linked films, were reviewed. The practical applications of CMCS-based food packaging films and edible coatings in food preservation are also showcased. This study emphasizes that the notable compatibility of CMCC with a range of polymers and additives has facilitated the development of multifunctional packaging films. These innovations, including antibacterial, antioxidant, and smart-indicating variants, have demonstrated remarkable efficacy in preserving fruits, aquatic products, poultry, and other perishable goods.

Preparation of Transglutaminase-Catalyzed Rice Bran Protein Emulsion Gels as a Curcumin Vehicle

Protein-based emulsion gels have tunable viscoelasticity that can be applied to improve the stability of bioactive ingredients. As the by-product of rice processing, rice bran protein (RBP) has high nutritional value and good digestibility, exhibiting unique value in the development of hypoallergenic formula. In this study, the effect of transglutaminase (TGase) cross-linking on the physicochemical properties of RBP emulsion gels was investigated. To improve the stability of curcumin against environmental stress, the entrapment efficiency and stability of curcumin in the emulsion gel systems were also evaluated. The results indicated that TGase increased the viscoelastic modulus of RBP emulsion gels, resulting in a solid-like structure. Moreover, the entrapment efficiency of curcumin was increased to 93.73% after adding TGase. The thermal stability and photo-stability of curcumin were enhanced to 79.54% and 85.87%, respectively, compared with the sample without TGase addition. The FTIR results showed that TGase induced the cross-linking of protein molecules and the secondary structure change in RBP. Additionally, SEM observation confirmed that the incorporation of TGase promoted the formation of a compact network structure. This study demonstrated the potential of RBP emulsion gels in protecting curcumin and might provide an alternative strategy to stabilize functional ingredients.

Advances in transglutaminase cross-linked protein-based food packaging films; a review

Pushed by the environmental pollution and health hazards of plastic packaging, the development of biodegradable food packaging films (FPFs) is a necessary and sustainable trend for social development. Most protein molecules have excellent film-forming properties as natural polymer matrices, and the assembled films have excellent barrier properties, but show defects such as low water resistance and poor mechanical properties. In order to improve the performance of protein-based films, transglutaminase (TG) is used as a safe and green cross-linking (CL) agent. This work covers recent developments on TG cross-linked protein-based FPFs, mainly comprising proteins of animal and plant origin, including gelatin, whey protein, zein, soy proteins, bitter vetch protein, etc. The chemical properties and reaction mechanism of TG are briefly introduced, focusing on the effects of TG CL on the physicochemical properties of different protein-based FPFs, including barrier properties, water resistance, mechanical properties and thermal stability. It is concluded that the addition of TG can significantly improve the physical and mechanical properties of protein-based films, mainly improving their water resistance, barrier, mechanical and thermal properties. It is worth noting that the effect of TG on the properties of protein-based films is not only related to the concentration of TG added, but also related to CL temperature and other factors. Moreover, TG can also be used in combination with other strategies to improve the properties of protein-based films.

Facile preparation of biocompatible and antibacterial water-soluble films using polyvinyl alcohol/carboxymethyl chitosan blend fibers via centrifugal spinning

Water-soluble polyvinyl alcohol/carboxymethyl chitosan (PVA/CMCS) blend fiber films were successfully prepared using a plane-collection centrifugal spinning machine. The addition of CMCS significantly increased the shear viscosity of the PVA/CMCS blend solution. The effects of spinning temperature on the shear viscosity and the centrifugal spinnability of PVA/CMCS blend solution were discussed. The PVA/CMCS blend fibers were uniform, and their average diameters ranged from 1.23 μm to 29.01 μm. It was found that the CMCS was distributed evenly in the PVA matrix and increased the crystallinity of PVA/CMCS blend fiber films. The hydrogen bonds between the hydroxyl group of PVA and the carboxymethyl group of CMCS were also detected. An in vitro cell study of human skin fibroblast cells on the PVA/CMCS blend fiber films confirmed biocompatibility. The maximum tensile strength and elongation at break of PVA/CMCS blend fiber films could reach 3.28 MPa and 29.52 %, respectively. The colony-plate-count tests indicated that the PVA16-CMCS2 presented 72.05 % and 21.36 % antibacterial rates against Staphylococcus aureus (10⁴ CFU/mL) and Escherichia coli (10³ CFU/mL), respectively. These values indicated that the newly prepared PVA/CMCS blend fiber films are promising materials for cosmetic and dermatological applications.

A Review of the Mechanism, Properties, and Applications of Hydrogels Prepared by Enzymatic Cross-linking

Hydrogels, as biological materials, are widely used in food, tissue engineering, and biomedical applications. Nevertheless, many issues remain in the preparation of hydrogels by physical and chemical methods, such as low bioaffinity, weak mechanical properties, and unstable structures, which also limit their applications in other fields. However, the enzymatic cross-linking method has the advantages of high catalytic efficiency, mild reaction conditions, and the presence of nontoxic substances. In this review, we evaluated the chemical, physical, and biological methods of preparing hydrogels and introduced three common cross-linking enzymes and their principles for preparing hydrogels. This review introduced the applications and properties of hydrogels prepared by the enzymatic method and also provided some suggestions regarding the current situation and future development of hydrogels prepared by enzymatic cross-linking.

Recent Advances in Natural Fibre-Based Materials for Food Packaging Applications

Packaging is one of the major domains in the food processing industry that reduces waste and enhances product shelf life. Recently, research and development have focused on bioplastics and bioresources to combat environmental issues caused by the alarming growth of single-use plastic waste food packaging. The demand for natural fibres has recently increased because of their low cost, biodegradability and eco-friendliness. This article reviewed recent developments in natural fibre-based food packaging materials. The first part discusses the introduction of natural fibres in food packaging, with a focus on fibre source, composition and selection parameters, while the second part investigates the physical and chemical ways to modify natural fibres. Several plant-derived fibre materials have been utilised in food packaging as reinforcements, fillers and packaging matrices. Recent investigations developed and modified natural fibre (physical and chemical treatments) into packaging using casting, melt mixing, hot pressing, compression moulding, injection moulding, etc. These techniques majorly improved the strength of bio-based packaging for commercialisation. This review also identified the main research bottlenecks and future study areas were suggested.

Carboxymethyl chitosan incorporated with gliadin/phlorotannin nanoparticles enables the formation of new active packaging films

Advanced carboxymethyl chitosan (CMCS) based functional films were fabricated by involving some amounts of gliadin/phlorotannin nanoparticles (GPNPs) using a solution casting method. GPNPs were synthesized by an antisolvent precipitation approach, and they presented a spherical morphology with a mean diameter of 145.30 ± 2.06 nm. The effect of GPNPs concentration on the structural, physical, antioxidant and antimicrobial properties of CMCS-GPNPs (C-G) functional films was evaluated. It was found that the added GPNPs were homogeneously distributed over the whole CMCS matrix, allowing to reduce the free volume of the nanocomposite matrix and subsequently improve the physical properties of the final film (evidenced by mechanical and water barrier properties). FT-IR spectra indicated the intermolecular interactions, such as hydrogen bonds and electrostatic interaction, within the matrix of the nanocomposite films were increased. Impressively, the anti-ultraviolet properties, antioxidant activity and antimicrobial behaviors of the as-formed C-G functional films were greatly enhanced compared to the pure CMCS film. All these results suggested that our as-prepared C-G nanocomposite films could be a promising food packaging material.

High antibacterial activity of chitosan films with covalent organic frameworks immobilized silver nanoparticles

In this study, chitosan (CS) film containing covalent organic frameworks (COFs) immobilized silver nanoparticles (AgNPs) were developed for food packaging with improved antibacterial activities and film properties. COFs-AgNPs were fabricated via in-situ synthesis of immobilizing AgNPs on COFs. Transmission electron microscope, Zeta potential, X-ray diffraction, element mapping and Fourier transform infrared spectroscopy confirmed the successful fabrication of COFs-AgNPs, and COFs-AgNPs showed superior antibacterial activity against S. aureus and E. coli. Furthermore, the as-prepared COFs-AgNPs composite was further used to fabricate CS composite films (CS/COFs-AgNPs) by a solution casting method. The findings showed that the tensile strength of the nanocomposite films enhanced dramatically with the increase of the COFs-AgNPs content, while the UV-visible light barrier property, water swelling and solubility properties, and water vapor permeability (WVP) decreased significantly. Not only that, the CS/COFs-AgNPs nanocomposite films also showed outstanding antibacterial activity and effectively prolonged the storage time of white crucian carp (Carassius auratus). As a result, CS/COFs-AgNPs nanocomposite films show great potential in active food packaging.