The effect of relative humidity on tensile strength and water vapor permeability in chitosan, fish gelatin and transglutaminase edible films

Effect of Trehalose/OEO/Tween 80/Tween 20 Addition on Physical Stability of Edible Packaging during Storage in Different Humidity Conditions

Edible packaging has been a topic of much discussion during recent years, mainly due to its lower environmental impact. This study aimed to investigate the properties of an edible packaging made from a combination of carrageenan, orange essential oil (OEO), and trehalose (Tre) under different humidity conditions. The films were analyzed based on their water content, solubility, and textural properties, such as strength and breaking strain. The results of the study showed that the addition of trehalose reduced the water content and increased the strength of the packaging, regardless of the humidity conditions. The inclusion of orange essential oil also contributed to lower water content, which led to more water-resistant packaging (during standard humidity conditions (45%)-c: 15.31%; Tre3OT80: 4.04%, Tre1OT80: 4.48%). The findings of this study have important implications for the production of stable and environmentally friendly edible packaging. The results demonstrate the potential of trehalose and orange essential oil as additives to enhance the properties of edible packaging, particularly in terms of its resistance to moisture. The best results were found in Tre1OT80 and Tre3OT80 samples. Moreover, the study emphasizes the importance of considering storage conditions in the development of edible packaging, as different humidity levels can significantly affect the packaging's properties and shelf life. The findings have practical applications for the food industry, particularly in the development of sustainable packaging solutions and for further studies where the application of this packaging can be analyzed for different foodstuffs.

Development and characterization of a novel biodegradable and antioxidant film based on marine seaweed sulfated polysaccharide

This research aims to produce an antioxidant and biodegradable polysaccharide film by using macroalgae agar and sulfated polysaccharide. Agar and sulfated polysaccharide (fucoidan) were extracted from Gracilaria corticata and Sargassum angustifolium macroalgae. Five treatments were conducted: (A) agar film (1%, W:V), (C) chitosan film (1%, W:V + 1% acetic acid), (AC) agar:chitosan composite (50:50, V:V), (ACF) AC film with fucoidan (0.5%, W:V), and (ACFA) ACF film with citric acid (30% of the dry weight of film) as a cross-linking agent. Then, 0.75% (V:V) of glycerol was added to all films. The physical, mechanical, antioxidant, color variations, microstructure (SEM), and Fourier transform infrared (FT-IR) spectroscopy were investigated. Based on the results, modifying the agar film with chitosan improved the mechanical strength, humidity, and solubility in the AC composite film (p < .05). Further, adding sulfated polysaccharide and citric acid cross-linking agent to the agar-chitosan composite led to a significant decrease in solubility, humidity, and permeability to water vapor in ACFA films (p < .05), indicating strong cross-linking and reduction in film pores based on the SEM pictures and FTIR results. However, the physical and mechanical properties of the agar-based film obtained from Gracilaria algae can be improved by adding chitosan and citric acid cross-linking agent, and the addition of fucoidan obtained from Sargassum algae has improved its antioxidant properties. This biodegradable film can be a good candidate for preserving perishable products.

Recent advances in carrageenan-based films for food packaging applications

In order to solve the increasingly serious environmental problems caused by plastic-based packaging, carrageenan-based films are drawing much attentions in food packaging applications, due to low cost, biodegradability, compatibility, and film-forming property. The purpose of this article is to present a comprehensive review of recent developments in carrageenan-based films, including fabrication strategies, physical and chemical properties and novel food packaging applications. Carrageenan can be extracted from red algae mainly by hydrolysis, ultrasonic-assisted and microwave-assisted extraction, and the combination of multiple extraction methods will be future trends in carrageenan extraction methods. Carrageenan can form homogeneous film-forming solutions and fabricate films mainly by direct coating, solvent casting and electrospinning, and mechanism of film formation was discussed in detail. Due to the inherent limitations of the pure carrageenan film, physical and chemical properties of carrageenan films were enhanced by incorporation with other compounds. Therefore, carrageenan-based films can be widely used for extending the shelf life of food and monitoring the food freshness by inhibiting microbial growth, reducing moisture loss and the respiration, etc. This article will provide useful guidelines for further research on carrageenan-based films.

Guar gum-sodium alginate nanocomposite film as a smart fluorescence-based humidity sensor: A smart packaging material

Perishable packed foods are easily damaged by the change in relative humidity. In this work, we demonstrate that guar gum- sodium alginate blending with glucose-glycerol carbon dots nanocomposite film can be used to detect relative humidity. The fabricated nanocomposite film was an excellent smart sensor based on the fluorescence 'on-off' mechanisms against humidity. The study demonstrates that at different relative humidity conditions, such as 11 %, 33 %, 75.30 %, 84 %, and 97 %, there is a change in the fluorescence of biocomposite films under UV light. The practical feasibility of the biocomposite developed film was tested in real conditions by placing a piece of bread with high humidity conditions wrapped with the developed nanocomposite film. It was observed that under such conditions, marked quenching of fluorescence was observed and hence detection of humidity was possible. Hence, the fabricated nanocomposite film can monitor the packed food freshness using just a UV light source. Such biopolymer nanocomposite is potential materials and may find application as smart packaging materials, especially as food packaging materials.

Preparation, Properties and Potential of Carrageenan-Based Hard Capsules for Replacing Gelatine: A Review

Intense efforts to develop alternative materials for gelatine as a drug-delivery system are progressing at a high rate. Some of the materials developed are hard capsules made from alginate, carrageenan, hypromellose and cellulose. However, there are still some disadvantages that must be minimised or eliminated for future use in drug-delivery systems. This review attempts to review the preparation and potential of seaweed-based, specifically carrageenan, hard capsules, summarise their properties and highlight their potential as an optional main component of hard capsules in a drug-delivery system. The characterisation methods reviewed were dimensional analysis, water and ash content, microbial activity, viscosity analysis, mechanical analysis, scanning electron microscopy, swelling degree analysis, gel permeation chromatography, Fourier-transform infrared spectroscopy and thermal analysis. The release kinetics of the capsule is highlighted as well. This review is expected to provide insights for new researchers developing innovative products from carrageenan-based hard capsules, which will support the development goals of the industry.

Trends in Chitosan as a Primary Biopolymer for Functional Films and Coatings Manufacture for Food and Natural Products

Some of the current challenges faced by the food industry deal with the natural ripening process and the short shelf-life of fresh and minimally processed products. The loss of vitamins and minerals, lipid oxidation, enzymatic browning, and growth of microorganisms have been the main issues for many years within the innovation and improvement of food packaging, which seeks to preserve and protect the product until its consumption. Most of the conventional packaging are petroleum-derived plastics, which after product consumption becomes a major concern due to environmental damage provoked by their difficult degradation. In this sense, many researchers have shown interest in edible films and coatings, which represent an environmentally friendly alternative for food packaging. To date, chitosan (CS) is among the most common materials in the formulation of these biodegradable packaging together with polysaccharides, proteins, and lipids. The good film-forming and biological properties (i.e., antimicrobial, antifungal, and antiviral) of CS have fostered its usage in food packaging. Therefore, the goal of this paper is to collect and discuss the latest development works (over the last five years) aimed at using CS in the manufacture of edible films and coatings for food preservation. Particular attention has been devoted to relevant findings in the field, together with the novel preparation protocols of such biodegradable packaging. Finally, recent trends in new concepts of composite films and coatings are also addressed.

Theoretical investigation into the cooperativity effect of 1,4-dimethoxy-D-glucosamine complex with Na+ and H2O

In order to explore the essence of the hydration process of chitin or chitosan in the presence of cation, the cooperativity effects between the H-bonding and Na⁺···molecule interactions in the 1,4-dimethoxy-D-glucosamine (DMGA) complexes with H₂O and Na⁺ were investigated at the B3LYP/6-311++G(d,p), M06-2X/6-311++G(2df,2p), and ωB97X-D/6-311++G(2df,2p) levels. The result shows that the complexes in which Na⁺ or H₂O is bonded simultaneously to the -NH and -OH groups connected to the C3 atom of DMGA are the most stable. The cooperativity and anti-cooperativity effects occur in DMGA···H₂O···DMGA and DMGA···Na⁺···H₂O, while only the cooperativities are confirmed in DMGA···Na⁺···DMGA. The cooperativity occurs in the DMGA···Na⁺···H₂O complexes without the hydration, while the anti-cooperativity occurs in those with the hydration. Furthermore, the cooperativity and anti-cooperativity in DMGA···Na⁺···H₂O are far stronger than those in DMGA···Na⁺···DMGA or DMGA···H₂O···DMGA. Therefore, a deduction is given that the cooperativity and anti-cooperativity effects play an important role in the hydration of chitin or chitosan in the presence of Na⁺. When only Na⁺ is linked with -OH and -NH groups of chitosan or chitin, due to the cooperativity effect, the hydration does not occur. When both Na⁺ and H₂O are linked with -OH and -NH groups, the anti-cooperativities are dominant in controlling of the aggregation process of Na⁺, H₂O, chitosan, and chitin, leading to the possible hydration. Atoms in molecules (AIM) analysis confirms the cooperativity and anti-cooperativity effects. Graphical abstract.

Microbial Transglutaminase as a Tool to Improve the Features of Hydrocolloid-Based Bioplastics

Several proteins from animal and plant origin act as microbial transglutaminase substrate, a crosslinking enzyme capable of introducing isopeptide bonds into proteins between the aminoacids glutamines and lysines. This feature has been widely exploited to modify the biological properties of many proteins, such as emulsifying, gelling, viscosity, and foaming. Besides, microbial transglutaminase has been used to prepare bioplastics that, because made of renewable molecules, are able to replace the high polluting plastics of petrochemical origin. In fact, most of the time, it has been shown that the microbial enzyme strengthens the matrix of protein-based bioplastics, thus, influencing the technological characteristics of the derived materials. In this review, an overview of the ability of many proteins to behave as good substrates of the enzyme and their ability to give rise to bioplastics with improved properties is presented. Different applications of this enzyme confirm its important role as an additive to recover high value-added protein containing by-products with a double aim (i) to produce environmentally friendly materials and (ii) to find alternative uses of wastes as renewable, cheap, and non-polluting sources. Both principles are in line with the bio-economy paradigm.

A Facile Fabrication of Biodegradable and Biocompatible Cross-Linked Gelatin as Screen Printing Substrates

This study focuses on preparation and valuation of the biodegradable, native, and modified gelatin film as screen-printing substrates. Modified gelatin film was prepared by crosslinking with various crosslinking agents and the electrode array was designed by screen-printing. It was observed that the swelling ratio of C-2, crosslinked with glutaraldehyde and EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide) was found to be lower (3.98%) than that of C-1 (crosslinked with only glutaraldehyde) (8.77%) and C-0 (without crosslinking) (28.15%). The obtained results indicate that the swelling ratios of both C-1 and C-2 were found to be lower than that of C-0 (control one without crosslinking). The Young's modulus for C-1 and C-2 was found to be 8.55 ± 0.57 and 23.72 ± 2.04 kPa, respectively. Hence, it was conveyed that the mechanical strength of C-2 was found to be two times higher than that of C-l, suggesting that the mechanical strength was enhanced upon dual crosslinking in this study also. The adhesion study indicates that silver ink adhesion on the gelation surface is better than that of carbon ink. In addition, the electrical response of C-2 with a screen-printed electrode (SPE) was found to be the same as the commercial polycarbonate (PC) substrate. The result of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay suggested that the silver SPE on C-2 was non-cytotoxic toward L929 fibroblast cells proliferation. The results indicated that C-2 gelatin is a promising material to act as a screen-printing substrate with excellent biodegradable and biocompatible properties.

Water desorption from a confined biopolymer

We study desorption of water from a confined biopolymer (chitosan thin films) by employing temperature dependent specular X-ray reflectivity and spectroscopic ellipsometry. The water desorption is found to occur via three distinct stages with significantly different desorption rates. The distinct rates of water desorption are attributed to the presence of different kinds of water with disparate mobilities inside the biopolymer film. We identify two characteristic temperatures (T_c1 and T_c2) at which the water desorption rate changes abruptly. Interestingly, the characteristic temperatures decrease with decreasing the film thickness. The thickness dependence of the characteristic temperature is interpreted in the context of a higher mobility of polymer chains at the free surface for polymers under one-dimensional confinement.

Film-forming ability of collagen hydrolysate extracted from leather solid wastes with chitosan

Discharges of huge quantities of leather solid wastes by leather industries and the increased use of synthetic packaging films have raised serious concerns on account of their environmental impacts. The paper focuses on the development and characterization of potential environmentally friendly composite films using collagen hydrolysate (CH) extracted from leather solid wastes and chitosan (C) to assess the feasibility of producing polymeric materials suitable for applications in packaging and wrapping purposes. Solid collagen-based protein hydrolysate was extracted from chromium-tanned leather wastes and analyzed to determine its chemical properties. With the goal of improving the physico-chemical performance of CH, three types of composite films (CH75/C25, CH50/C50, CH25/C75) were prepared with increasing concentrations of C, and some of their physical and functional properties were characterized. The results indicated that the addition of C caused increase (p < 0.05) in the thickness, tensile strength (TS), elasticity modulus (EM), and water vapor permeability (WVP), leading to stronger films as compared with CH film, but significantly (p < 0.05) decreased the elongation at break (EAB) and solubility of films (p < 0.05). The light barrier measurements present low values of transparency at 600 nm of the CH/C films, indicating that the films are very transparent and they have excellent barrier properties against UV light. The structural properties investigated by FTIR and DSC showed total miscibility between both polymers. Scanning electron micrographs revealed that CH/C composite films showed a compact homogeneous structure. These results demonstrate the potential application of CH/C composite films in packaging industry.