Water vapor sorption and permeability of sustainable alginate/collagen/SiO2 composite films

Alginate-based active and intelligent packaging: Preparation, properties, and applications

Alginate-based packaging materials have emerged as promising alternatives to conventional petroleum-based plastics due to their biodegradability, renewability, and versatile functionalities. This review provides a comprehensive analysis of the recent advances in the development and application of alginate-based films and coatings for food packaging. The composition and fabrication methods of alginate-based packaging materials are discussed, highlighting the incorporation of various functional compounds to enhance their physicochemical properties. The mechanisms of action and the factors influencing the release and migration of active compounds from the alginate matrix are explored. The application of alginate-based packaging materials for the preservation of various food products, including meat, fish, dairy, fruits, and vegetables, is reviewed, demonstrating their effectiveness in extending shelf-life and maintaining quality. The development of alginate-based pH-sensitive indicators for intelligent food packaging is also discussed, focusing on the colorimetric response of natural pigments to spoilage-related pH changes. Furthermore, the review highlights the challenges and future perspectives of alginate-based packaging materials, emphasizing the need for novel strategies to improve their performance, sustainability, and industrial adoption.

Moisture loss inhibition with biopolymer films for preservation of fruits and vegetables: A review

In cold storage, fruits and vegetables still keep a low respiratory rate. Although cold storage is beneficial to maintain the quality of some fruits and vegetables, several factors (temperature and humidity fluctuations, heat inflow, air velocity, light, etc.) will accelerate moisture loss. Biopolymer films have attracted great attention for fruits and vegetables preservation because of their biodegradable and barrier properties. However, there is still a certain amount of water transfer occurring between storage environment/biopolymer films/fruits and vegetables (EFF). The effect of biopolymer films to inhibit moisture loss of fruits and vegetables and the water transfer mechanism in EFF system need to be studied systematically. Therefore, the moisture loss of fruits and vegetables, crucial properties, major components, fabrication methods, and formation mechanisms of biopolymer films were reviewed. Further, this study highlights the EFF system, responses of fruits and vegetables, and water transfer in EFF. This work aims to clarify the characteristics of EFF members, their influence on each other, and water transfer, which is conducive to improving the preservation efficiency of fruits and vegetables purposefully in future studies. In addition, the prospects of studies in EFF systems are shown.

Smart and UV-Resistant Edible Coating and Films Based on Alginate, Whey Protein, and Curcumin

In this work, smart edible coating and films with excellent UV barrier properties were prepared from alginate, whey protein isolate, and curcumin. The primary focus of this investigation centered on assessing the impact of whey protein and curcumin on the physical and functional properties of the alginate films. Whey protein reduced the film transparency while simultaneously enhancing the hydrophobicity and antioxidant properties of the alginate film. Curcumin imparted a yellow hue to the film, consequently decreasing the transparency of the film. It also substantially improved hydrophobicity, antioxidant activity, and UV-blocking efficiency within the films. Remarkably, curcumin demonstrated a significant reduction in the water vapor transmission rate of the film. For the preservation of apples, a higher concentration of curcumin was required, which effectively suppressed the respiration rate and moisture loss post-harvest, resulting in an extended shelf-life for the apples. As a result, the coated apples exhibited significantly reduced enzymatic browning and weight loss in comparison to their uncoated counterparts. Furthermore, these curcumin-containing films underwent a reversible color change from orange to red when exposed to ammonia vapor. This attribute highlights the potential of the developed coating and film as a smart, active food packaging solution, particularly for light-sensitive food products.

A comparison study on effects of polyglycerols on physical properties of alginate films

The water solubility and brittleness of unplasticized sodium alginate (SA) films hinder their widely application. Glycerol (GLY), the most commonly used plasticizer, is compatible with alginate due to the formation of hydrogen bonding owing to the hydroxyl functional groups. However, GLY is a small water-soluble molecule, and the resulting leaching problem may lead to decline in mechanical properties of SA films. Aimed at better plasticizers for alginate (ALG) films, this work focuses on the effects of polymerization degree of polyglycerol on physical properties of ALG films. The cross-sectional morphology, crystallinity, mechanical and thermal properties, water solubility, water content and barrier property of ALG films plasticized with GLY, triglycerol (TG) and decaglycerol (DG) were characterized and discussed. Results illustrated that owing to the long molecular chains of TG and DG and their strong interactions with ALG matrix, the plasticized films possessed better mechanical properties, higher water content and lower water solubility. Moreover, it was worth mentioning that even after water treatment, the mechanical properties of ALG-TG and ALG-DG films were superior than that plasticized with GLY. The results of this study were believed to provide particular insights into the plasticization mechanism and the improvement in performance of SA films in packaging applications.

Packaging films based on biopolymers from seafood processing wastes: Preparation, properties, and their applications for shelf-life extension of seafoods-A comprehensive review

Biopolymers derived from seafood processing byproducts are used to prepare active and biodegradable films as the packaging of food products. These films possess bioactivities to enhance the shelf life of packed foods by proactively releasing antimicrobial/antioxidative agents into the foods and providing sufficient barrier properties. Seafood processing byproducts are an eminent source of valuable compounds, including biopolymers and bioactive compounds. These biopolymers, including collagen, gelatin, chitosan, and muscle proteins, could be used to prepare robust and sustainable food packaging with some antimicrobial agents or antioxidants, for example, plant extracts rich in polyphenols or essential oils. These active packaging are not only biodegradable but also prevent the deterioration of packed foods caused by spoilage microorganisms as well as chemical deterioration. Seafood discards have a promising benefit for the development of environmentally friendly food packaging systems via the appropriate preparation methods or techniques. Therefore, the green packaging from seafood leftover can be better exploited and replace the synthetic counterpart.

Preparation and performance testing of corn starch/pullulan/gallic acid multicomponent composite films for active food packaging

The present study investigated the mechanical characteristics, hydrophobicity, antioxidant and antibacterial properties, FTIR, SEM and XRD of films fabricated with corn starch and pullulan (CS/PUL) by adding different concentrations of Gallic acid (GA) (0%, 0.5%, 1.0%, 1.5% w/v). The mechanical strength and opacity of CS/PUL films were enhanced by the addition of 1.0% GA. The water vapor permeability (WVP) of CS/PUL films was significantly lower in films with GA compared to those without (P < 0.05). The addition of GA, especially at concentrations of 1.0% and 1.5%, resulted in considerably better free radical scavenging activities on DPPH than films without GA (P < 0.05). Interestingly, the highest water contact angle (WCA) value was observed in films with 0.5% GA, indicating stronger hydrophobicity. Furthermore, the antibacterial capabilities of the films, particularly against E. coli and P. aeruginosa, improved with an increase in GA concentration. The results of FTIR, SEM and XRD analyses showed that GA was well distributed in the CS/PUL matrix.

Alternative flexible plastic packaging for instant coffees

Instant coffees are consumed worldwide and their packages must protect them mainly from moisture gain. Flexible packaging stand-up pouches made by PET/Al foil/LDPE are currently used but, the look for alternative materials is interesting to replace the aluminum foil with reducing costs and focusing on sustainability. Therefore, the aim of this study was to evaluate the quality loss of freeze-dried and spray-dried (agglomerated and powder) instant coffees during 365 days at 25 °C/75% RH, packaged in five plastic structures: PET (polyethylene terephthalate)/Al (aluminum) foil/LDPE (low density polyethylene), LDPE/HDPE (high density polyethylene)/LDPE, BOPP (biaxially oriented polypropylene)/BOPP met (metallized)/PP, PET/PET met/LDPE and PET/BOPP met/LDPE. The results were compared with the shelf-life estimated by modeling the moisture sorption isotherms of the products by mathematical models. Results indicated that the lower the barrier to water vapor of the packaging material, the greater the gains in moisture and water activity of the instant coffees and in addition to being thermally less stable. After 365 days of storage, the three soluble coffees still had acceptable characteristics in the five packaging structures, indicating that it is possible to replace the currently used laminate, which contains aluminum foil, with recyclable structures. However, the greatest stability for the coffees was obtained using the alternative structures: BOPP/BOPP met/PP and LDPE/HDPE/LDPE, a result that was in concordance with that obtained by mathematical modeling.

Characterization of Nano-SiO2/Zein Film Prepared Using Ultrasonic Treatment and the Ability of the Prepared Film to Resist Different Storage Environments

This study has developed, ultrasound-assisted, a novel food packaging film (U-zein/SiO2) for food packaging applications. Incorporating an optimal concentration of 18 mg/mL of nano-SiO2 and subjecting the film to 10 min of ultrasonic treatment resulted in a remarkable increase of 32.89% in elongation at break and 55.86% in tensile strength. In addition, the incorporation of nano-SiO2 effectively reduces the water content and solubility of the composite film, resulting in improved water/oxygen barrier properties. These physiochemical properties were further improved with the application of ultrasound. The analysis of attenuated total reflectance-Fourier transform infrared, X-ray diffraction, differential scanning calorimetry, and scanning electronic microscope demonstrated that the ultrasound treatment improved the hydrogen bonds, improved thermal stability, molecular arrangement, structure stability, and intermolecular compatibility of the composite film, resulting in enhanced physio-mechanical properties of the film. In addition, the ultrasound treatment led to a smoother film surface and reduced the pores on the film's cross-section. Moreover, the U-zein/SiO2 film exhibited excellent mechanical and water/oxygen barrier properties in different storage environments over a period of 30 days. These results offer sound theoretical support for the practical application of the prepared preservative film.

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

Biopolymer-based packaging materials have become of greater interest to the world due to their biodegradability, renewability, and biocompatibility. In recent years, numerous biopolymers-such as starch, chitosan, carrageenan, polylactic acid, etc.-have been investigated for their potential application in food packaging. Reinforcement agents such as nanofillers and active agents improve the properties of the biopolymers, making them suitable for active and intelligent packaging. Some of the packaging materials, e.g., cellulose, starch, polylactic acid, and polybutylene adipate terephthalate, are currently used in the packaging industry. The trend of using biopolymers in the packaging industry has increased immensely; therefore, many legislations have been approved by various organizations. This review article describes various challenges and possible solutions associated with food packaging materials. It covers a wide range of biopolymers used in food packaging and the limitations of using them in their pure form. Finally, a SWOT analysis is presented for biopolymers, and the future trends are discussed. Biopolymers are eco-friendly, biodegradable, nontoxic, renewable, and biocompatible alternatives to synthetic packaging materials. Research shows that biopolymer-based packaging materials are of great essence in combined form, and further studies are needed for them to be used as an alternative packaging material.

Performance Analysis of Loose-Fill Thermal Insulation from Wood Scobs Coated with Liquid Glass, Tung Oil, and Expandable Graphite Mixture

The current study presents the results of monitoring the behavior of loose-fill thermal insulating material for buildings made of wood scobs (WS), which were coated with one, two, and three component-based coatings from liquid glass (LG), tung oil (TO), and expandable graphite (EG). The thermal conductivity of samples in the dry state and under normal laboratory conditions, short-term water absorption by partial immersion, surface wettability, and water vapor permeability were evaluated, and regression equations describing the variations in numerical values of specified properties under different amounts of each coating component were presented. It was shown that LG and TO act as hydrophobic layers that, in conjunction, reduce water absorption by a maximum of 274%, have a contact angle equal to 86°, and lower thermal conductivity by 55% in the dry state due to the specifics of the layer formed on the surface of WS. The addition of EG to LG coating resulted in insignificantly changed water absorption and thermal conductivity values, indicating the potential of this material to be used to improve the fire resistance of wood-based composites in the future. The results showed that the three-component layer of LG/TO/EG reduces water absorption by a maximum of 72%, increases thermal conductivity in the dry state by a minimum of 0.4%, and increases the contact angle to 81° at 100 wt.% LG. The changes in water vapor permeability of all compositions were determined to be insignificant.

Strategies adopted for the preparation of sodium alginate–based nanocomposites and their role as catalytic, antibacterial, and antifungal agents

Alginate extracted from the marine brown algae is a massively utilized biopolymer in multiple fields such as microreactors for the fabrication of metal nanoparticles along with other polymeric and nonpolymeric materials to enhance their mechanical strength. These sodium alginate (Na-Alg)-based fabricated nanocomposites find applications in the field of catalysis and biological treatment as antibacterial/antifungal agent due to the synergistic properties of Na-Alg and fabricated metal nanoparticles (NPs). Na-Alg offers mechanical strength and nanoparticles provide high reactivity due to their small size. Sodium alginate exhibits hydroxyl and carboxylate functional groups that can easily interact with the metal nanoparticles to form composite particles. The research on the preparation of Na-Alg–based nanoparticles and nanoaggregates have been started recently but developed quickly due to their extensive applications in different fields. This review article encircles different methods of preparation of sodium alginate–based metal nanocomposites; analytical techniques reported to monitor the formation of these nanocomposites and used to characterize these nanocomposites as well as applications of these nanocomposites as catalyst, antibacterial, and antifungal agent.

A rethinking of collagen as tough biomaterials in meat packaging: assembly from native to synthetic

Due to the high moisture-associated typical rheology and the changeable and harsh processing conditions in the production process, packaging materials for meat products have higher requirements including a sufficient mechanical strength and proper ductility. Collagen, a highly conserved structural protein consisting of a triple helix of Gly-X-Y repeats, has been proved to be suitable packaging material for meat products. The treated animal digestive tract (i.e. the casing) is the perfect natural packaging material for wrapping meat into sausage. Its thin walls, strong toughness and impact resistance make it the oldest and best edible meat packaging. Collagen casing is another wisdom of meat packaging, which is made by collagen fibers from hide skin, presenting a rapid growth in casing market. To strengthen mechanical strength and barrier behaviors of collagen-based packaging materials, different physical, chemical, and biological cross-linking methods are springing up exuberantly, as well as a variety of reinforcement approaches including nanotechnology. In addition, the rapid development of biomimetic technology also provides a good research idea and means for the promotion of collagen's assembly and relevant mechanical properties. This review can offer some reference on fundamental theory and practical application of collagenous materials in meat products.

Biopolymer-Based Films from Sodium Alginate and Citrus Pectin Reinforced with SiO2

Blend films based on sodium alginate (SA) and citrus pectin (P) reinforced with different concentrations of SiO₂ (0–10% w/w) were developed in this study. From the morphological (SEM) and structural (FT-IR) evaluation, it was verified that the incorporation of the reinforcing agent did not drastically modify the microstructure of the films, nor did new chemical bonds form. However, the XRD results suggested a slight reduction in the crystallinities of the blends by the incorporation of SiO₂. Among the formulations prepared, the addition of a 5% reinforcing agent was responsible for the simultaneous improvement of mechanical and barrier properties. Comparing the control sample (SA/P) with the SA/P/5.0%SiO₂ film, the tensile strength increased from 27.7 ± 3.7 to 40.6 ± 4.5 MPa, and the water-vapor transmission rate decreased from 319.8 ± 38.7 to 288.9 ± 23.5 g m⁻² day⁻¹. Therefore, SiO_2, as a reinforcing agent in SA/P blends, represents a simple and effective strategy for improving the properties of biopolymer-based films in applications, such as packaging.

Improving the mechanical properties and thermal stability of sodium alginate/hydrolyzed collagen films through the incorporation of SiO2

Biopolymer-based films have become leading alternatives to traditional fossil-based packaging plastics. Among the countless types of biopolymers with potential for such applications, films containing hydrolyzed collagen in their composition were scarcely explored. This study determined the effect of different loads of nano-SiO₂ (0, 2, 6, 8 and 10% w/w of sodium alginate) in the sodium alginate (SA) and hydrolyzed collagen (HC) blend films in terms of structure, thickness, mechanical properties, and thermal stability. The results indicated an improvement in the general mechanical and thermal behavior. Tensile strength increased from 18.2 MPa (control sample) to 25.4 MPa for the SA/HC film incorporated with 10% nano-SiO₂. In the same condition, the film's elongation at break improved impressively (from 19.5 to 35.8%). Thermal stability improved slightly for all proportions of nano-SiO₂. Therefore, the addition of nano-SiO₂ can be an easy and simple strategy to improve crucial properties of SA/HC blend films, increasing its performance for future application as sustainable packaging.