Recent advances in protein derived bionanocomposites for food packaging applications

Abstract

This review article critically presents a comprehensive overview of the current advances in the research and development of proteins derived bionanocomposites used in food packaging applications. The recent interest in protein-based biomaterials is due to sustainability, renewability, biodegradability and low carbon footprint. The inherent drawbacks of proteins-based materials for food packaging applications are their low mechanical strength, poor thermal, barrier and inferior physicochemical properties. The nanoreinforced bio-based polymers called bionanocomposites provide an opportunity to overcome these issues and have ability to supersede non-biodegradable food packaging plastics produced from petroleum resources. So far, most studied protein derived bionanocomposites suitable for food packaging are soy protein isolates (SPI) and gelatin proteins. Layered silicates are the most promising nanofillers used to increase strength, improve heat resistance and enhance barrier properties of proteins derived materials while montmorillonites (MMT) is the most commonly used silicate nanofiller. This review emphases on the processing strategies used for proteins-based biomaterials, their mechanical and moisture barrier properties for food packaging applications. Different proteins and nanofillers that have been studied to date in proteins derived food packaging applications are also discussed in detail.     

Effects of virgin coconut oil on the physicochemical,morphological and antibacterial properties of potato starch-based biodegradable films

This study investigated the effects of adding different concentrations of virgin coconut oil (VCO) on the optical, mechanical, thermodynamic and antimicrobial properties, as well as water vapour permeability and morphology of potato starch-based biodegradable films. Increasing VCO concentrations caused a rise in the light transmittance of the films from 2.13 to 4.79 mm⁻¹ and a decrease in water vapour transmittance from 6.77 to 2.12 (10⁻⁵ GPa⁻¹ h⁻¹ m⁻¹). At a VCO concentration of 14 wt% (based on potato starch), the tensile strength reached its highest value (19.98 MPa). Scanning electron microscopy showed that the surface of the film became smoother as VCO concentration increased. The addition of VCO inhibited the growth of Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. In conclusion, VCO supplementation improved the mechanical, antibacterial and water barrier properties of starch-based films. These results could expand the scope of the application of starch-based films in food packaging.     

Unraveling the Potential of Innovative Eco-friendly Thermoplastic Starch/SEBS-g-MA/Graphene Oxide Bionanocomposites

The increasing focus on bionanocomposites as environmentally friendly solutions for sustainable applications forms the crux of this study. This study explores the influence of incorporating 2% graphene oxide (GO) on the mechanical and thermal characteristics of blends containing glycerol plasticized thermoplastic starch (TPS) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (SEBS-g-MA), based matrix films through a solution casting method. Starch is successfully obtained from three varied sources: corn, cassava, and potato, with confirmation via fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. The authors formulate and examine varying proportions of TPS/SEBS-g-MA (ranging from 10 to 50 wt.%), focusing on their biodegradability, and find that a 10 wt.% SEBS-g-MA concentration yields optimal degradation rates, thus this is kept constant. The bionanocomposite films are probed using techniques such as FTIR, XRD, mechanical strength testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water absorption, and biodegradability studies. These results indicate that GO incorporation results in a robust hydrogen bonding network within the cassava starch-based bionanocomposite films, enhancing their mechanical strength while decreasing their moisture absorption. Upgraded thermal properties of these films are also evident from the results. Consequently, these materials show promising utility, particularly in the realm of food packaging.     

Effect of cellulose fibers addition on the mechanical properties and water vapor barrier of starch-based films

Starch-based films have promising application on food packaging, because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of this work was to enhance these properties by reinforcing the films with cellulose fibers. Besides, the influences of both the solubility coefficient of water in the films (β) and the diffusion coefficient of water vapor through the films (D^w) on the films' water vapor permeability (K^w) were investigated. Films were prepared by the so-called casting technique, from film-forming suspensions of cassava starch, cellulose fibers (1.2 mm long and 0.1 mm of diameter), glycerol and water. The influence of fibers addition on K^w was determined at three relative humidity gradient ranges, ΔRH (2–33%, 33–64% and 64–90%). Films reinforced with cellulose fibers showed higher tensile strength and lower deformation capacity, and presented lower K^w than films without fibers. K^w showed strong dependency of β and D^w, presenting values up to 2–3 times greater at ΔRH = 64–90% than at ΔRH = 33–64%, depending on the film formulation. Therefore, adding cellulose fibers to starch-based films is a viable alternative to improve their mechanical and water barrier properties. Besides, this work showed the importance of determining film's water vapor permeability simulating the real environmental conditions the film will be used.     

Halloysite Nanotubes/Polyethylene Nanocomposites for Active Food Packaging Materials with Ethylene Scavenging and Gas Barrier Properties

Novel polymeric active food packaging films comprising halloysite nanotubes (HNTs) as active agents were developed. HNTs which are hollow tubular clay nanoparticles were utilized as nanofillers absorbing the naturally produced ethylene gas that causes softening and aging of fruits and vegetables; at the same time, limiting the migration of spoilage-inducing gas molecules within the polymer matrix. HNT/polyethylene (HNT/PE) nanocomposite films demonstrated larger ethylene scavenging capacity and lower oxygen and water vapor transmission rates than neat PE films. Nanocomposite films were shown to slow down the ripening process of bananas and retain the firmness of tomatoes due to their ethylene scavenging properties. Furthermore, nanocomposite films also slowed down the weight loss of strawberries and aerobic bacterial growth on chicken surfaces due to their water vapor and oxygen barrier properties. HNT/PE nanocomposite films demonstrated here can greatly contribute to food safety as active food packaging materials that can improve the quality and shelf life of fresh food products.     

Wheat gluten–based coatings and films: Preparation,properties, and applications

Effective food packaging that can protect foodstuffs from physical, chemical, and biological damage and maintain freshness and quality is essential to the food industry. Wheat gluten shows promise as food packaging materials due to its edibility, biodegradability, wide availability, low cost, film-forming potential, and high resistance to oxygen. The low mechanical properties and poor water permeability of wheat gluten coatings and films limit their wide applications; however, some inferior properties can be improved through various solutions. This work presents a comprehensive review about wheat gluten–based coatings and films, including their formulation, processing methods, properties, functions, and applications. The mechanical and water resistance properties of coatings and films can be reinforced through wheat gluten modification, combinations of different processing methods, and the incorporation of reinforcing macromolecules, antioxidants, and nanofillers. Antioxidants and antimicrobial agents added to wheat gluten can inhibit microbial growth on foodstuffs, maintain food quality, and extend shelf life. Performances of wheat gluten–based coatings and films can be further improved to expand their applications in food packaging. Current research gaps are identified. Future research is needed to examine the optimal formulation and processing of wheat gluten–based coatings and films and their performance.     

Mechanical and barrier properties of composite films based on rice flour and cellulose fibers

Rice flour is a low-cost starchy material, produced from rice that is broken during processing. Rice flour-based films have promising application on food packaging, because of their environmental appeal and low cost. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of this study was to develop biodegradable films based on rice flour and enhance their properties by reinforcing them with cellulose fibers. In this way, rice flour films with and without fibers were prepared by casting, with glycerol or sorbitol as plasticizer. Their physicochemical, microscopic and mechanical properties were studied. SEM analysis of films revealed compact structures. Films prepared with fibers presented lower water vapor permeabilities if compared with films without fibers. Films containing sorbitol were less permeable to water and more rigid. The incorporation of fibers reinforced mechanically the flour-based films, which presented higher tensile strength, but did not influence their deformation capacity. Therefore, preparing biodegradable films from rice flour is a new alternative of using this raw material. The use of cellulose fibers as reinforcing agent is a viable alternative to improve the properties of rice flour-based films, because they are biodegradable and available at low cost.     

Regulating the Function of Nanocomposite Made from Hydroxypropyl Methyl Cellulose with Bacterial Cellulose Nanocrystal

Hydroxypropyl methyl cellulose(HPMC)-based hybrid nanocomposites reinforced with bacterial cellulose nanocrystals(BCNC) were prepared and characterized.The HPMC nanocomposites exhibited good thermal stability,with a thermogravimetric peak temperature of around 346℃.The addition of BCNC did not significantly affect the thermal degradation temperature or improve the transparency of HPMC nanocomposites.However,the addition of BCNC favorably affected the light scattering properties of the nanocomposites and enhanced mechanical properties such as tensile stress and Young's modulus from 65 MPa and 1.5 GPa up to 139 MPa and 3.2 GPa,respectively.The oxygen permeability of the HPMC nanocomposites also increased with increase in the amount of BCNC added.     

Producing novel sago starch based food packaging films by incorporating lignin isolated from oil palm black liquor waste

Poor mechanical and barrier properties of starch-based films can be improved by incorporating natural polymer such as lignin. In the present study, novel food packaging films were prepared by casting method from sago palm (Metroxylon sagu) starch (as film matrix with 30% w/w glycerol as plasticizer) by adding lignin isolated from oil palm black liquor waste (from empty fruit bunch), as a reinforcing material (1, 2, 3, 4 and 5% v/w). Results showed packaging films produced by incorporation of isolated lignin to improve selected thermo-mechanical and barrier properties with significant reduction in water vapor permeability, and improved water resistance and seal strength. It is concluded that lignin isolated from oil palm black liquor waste to have great potential to be explored for food packaging purposes. Moreover, this packaging film will be more economical and environmental friendly.     

Copper-based nanoparticles for biopolymer-based functional films in food packaging applications

This review summarizes the latest developments in the design, fabrication, and application of various Cu-based nanofillers to prepare biopolymer-based functional packaging films, focusing on the effects of inorganic nanoparticles on the optical, mechanical, gas barrier properties, moisture sensitivity, and functional properties of the films. In addition, the potential application of Cu-based nanoparticle-added biopolymer films for fresh food preservation and the effect of nanoparticle migration on food safety were discussed. The incorporation of Cu-based nanoparticles improved the film properties with enhanced functional performance. Cu-based nanoparticles such as copper oxide, copper sulfide, copper ions, and copper alloys affect biopolymer-based films differently. The properties of composite films containing Cu-based nanoparticles depend on the concentration of the filler, the state of dispersion, and the interaction of the nanoparticles with the biopolymer matrix in the film. The composite film filled with Cu-based nanoparticles effectively extended the shelf life by maintaining the quality of various fresh foods and securing safety. However, studies on the migration characteristics and safety of copper-based nanoparticle food packaging films are currently being conducted on plastic-based films such as polyethylene, and research on bio-based films is limited.     

Development of Antibacterial Carboxymethyl Cellulose‐Based Nanobiocomposite Films Containing Various Metallic Nanoparticles for Food Packaging Applications

In this study, silver (Ag), zinc oxide (ZnO), and copper oxide (CuO) metallic nanoparticles were used in preparation of carboxymethyl cellulose (CMC) nanobiocomposite films. Scanning electron microscopy (SEM), X‐ray diffraction (EDXA), water vapor permeability (WVP), ultraviolet and visible light (UV–Vis) spectroscopy, and mechanical and microbial tests were used to determine the characteristics of the obtained active films. SEM results showed that the CMC nanobiocomposite films had roughness deflection levels and the EDXA test confirmed the presence of Ag, ZnO, and Cuo nanoparticles in the biopolymer tissue. UV–Vis spectroscopy confirmed that with addition of metallic nanoparticles to the pure CMC film, absorption rate increased and WVP decreased. In the mechanical tests, addition of nanoparticles also increased the tensile strength of the films, and the nanobiocomposite films exhibited higher resistance compared to the pure CMC film. Films incorporating metallic nanoparticles showed antibacterial properties against Escherichia coli and Staphylococcus aureus growth. Thus, nanobiocomposite films can be used as active packaging films and could increase the shelf‐life of the food.     

淀粉基膜的制备及应用研究进展

淀粉是除纤维素外的第二大可再生原料,淀粉基膜绿色环保、安全无毒、可生物降解,缓解了合成材料的不可降解对生存环境的污染和原料日益枯竭的压力,实现资源的可持续发展,是当今最具有发展前景的新型材料之一。文章对淀粉基膜的制备方法进行了综述,介绍了湿法、干法制备淀粉基膜及其物理化学性质,阐述了淀粉基膜在食品保鲜、包装等领域的应用,并对淀粉基膜的应用前景进行展望。     

Preparation and characterization of whey protein isolate films reinforced with porous silica coated titania nanoparticles

Whey protein isolate (WPI) films embedded with TiO₂@@SiO₂ (porous silica (SiO₂) coated titania (TiO₂)) nanoparticles for improved mechanical properties were prepared by solution casting. A WPI solution of 1.5 wt% TiO₂@@SiO₂ nanoparticles was subjected to sonication at amplitudes of 0, 16, 80 and 160 μm prior to casting in order to improve the film forming properties of protein and to obtain a uniform distribution of nanoparticles in the WPI films. The physical and mechanical properties of the films were determined by dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and tensile testing. Water vapor permeability (WVP) measurements revealed that the water vapor transmission rates are slightly influenced by sonication conditions and nanoparticle loading. The DMA results showed that, at high sonication levels, addition of nanoparticles prevented protein agglomeration. The thermal stability of the materials revealed the presence of 3–4 degradation stages in oxidizing the protein films. The addition of nanoparticles strengthens the WPI film, as evidenced by tensile stress analysis. Sonication improved nanoparticle distribution in film matrix; such films can potentially become effective packaging materials to enhance food quality and safety.     

可食性肉桂精油复合膜的制备及其缓释性能

为了拓展肉桂精油（cinnamon essential oil, CEO）的应用途径,将CEO作为活性物质加入到氧化羟丙基木薯淀粉中,制备出复合膜。以力学性能、阻隔性能作为测试指标,通过单因素和正交试验优化CEO膜制备工艺,并测定其在不同食品模拟物中的释放速率。结果表明,淀粉质量分数为5.0%（m/v,以蒸馏水体积为基准）,CEO、甘油、吐温-80质量分数分别为1.5%、1.0%、1.0%（m/v,以淀粉溶液体积为基准）时,制得薄膜性能最好,断裂伸长率和抗拉强度较大,分别为27.87%和1.42 MPa,水蒸气透过系数与透油数较小,为1.27×10?12 g·cm/cm2·s·Pa和0.2131 g·mm/mm2·d,透光率30.56%;在同种食品模拟物中,CEO的释放量达到最大值的时间随着CEO含量增多而延长;在不同食品模拟物中,CEO在水包油乳状液和含酒精食品模拟物中释放速率最快,在脂肪食品模拟物中最慢。结果表明CEO可改善淀粉基膜的阻隔性能和机械性能,制备出的CEO膜有利于油脂类食品的包装,CEO可以缓慢释放,较长时间发挥活性作用。     

Enhanced Redispersibility of Cellulose Nanocrystals in Water via Surface Adsorption of Hydrolyzed Sugars from Corresponding Cellulose Nanocrystal Fabrication

Generally, hydrogen bonds are formed between cellulose nanocrystals (CNCs) during their water removal and drying, leading to the irreversible aggregation of CNCs, and thus a poor water-redispersibility. The present study demonstrated a novel approach that involved using hydrolyzed sugars generated from the corresponding CNC production as redispersing agents to enhance the redispersibility of CNCs. Experimental data indicated that hydrolyzed sugars can be adsorbed onto CNCs through ethanol precipitation. The oven-dried CNCs onto which hydrolyzed sugars were adsorbed via ethanol precipitation were homogeneously redispersed in water. The redispersed CNCs showed the particle size distribution, Zeta potential, and thermal decomposition properties similar to those of the CNCs without drying. This method may improve the use of hydrolyzed sugars obtained in the hydrolysate from the corresponding CNC production, as well as facilitate the transportation and storage of CNCs.     

Recent advances in biobased and biodegradable polymer nanocomposites,nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs—this is biosynthesized from plant extracts–showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.     

Nanocellulose Reinforced Chitosan Composite Films as Affected by Nanofiller Loading and Plasticizer Content

ABSTRACT: Chitosan is a biopolymer obtained by N-deacetylation of chitin, produced from shellfish waste, which may be employed to elaborate edible films or coatings to enhance shelf life of food products. This study was conducted to evaluate the effect of different concentrations of nanofiller (cellulose nanofibers, CNF) and plasticizer (glycerol) on tensile properties (tensile strength—TS, elongation at break—EB, and Young's modulus—YM), water vapor permeability (WVP), and glass transition temperature (T_g) of chitosan edible films, and to establish a formulation to optimize their properties. The experiment was conducted according to a central composite design, with 2 variables: CNF (0 to 20 g/100 g) and glycerol (0 to 30 g/100 g) concentrations in the film (on a dry basis), which was produced by the so-called casting technique. Most responses (except by EB) were favored by high CNF concentrations and low glycerol contents. The optimization was based on maximizing TS, YM, and T_g, and decreasing WVP, while maintaining a minimum acceptable EB of 10%. The optimum conditions were defined as: glycerol concentration, 18 g/100 g; and CNF concentration, 15 g/100 g. AFM imaging of films suggested good dispersion of the CNF and good CNF-matrix interactions, which explains the good performance of the nanocomposite films. Practical Application: Chitosan is a biodegradable polymer which may be used to elaborate edible films or coatings to enhance shelf life of foods. This study demonstrates how cellulose nanofibers (CNF) can improve the mechanical and water vapor barrier properties of chitosan films. A nanocomposite film with 15% CNF and plasticized with 18% glycerol was comparable to some synthetic polymers in terms of strength and stiffness, but with poorer elongation and water vapor barrier, indicating that they can be used for applications that do not require high flexibility and/or water vapor barrier. The more important advantage of such films when compared to synthetic polymer films is their environmentally friendly properties.     

含五倍子水提物的魔芋葡甘聚糖/乙基纤维素膜理化性和抗菌性研究

以魔芋葡甘聚糖（KGM）和乙基纤维素（EC）为基材,添加五倍子提取物制备可食性抗菌膜。测定了复合膜的拉伸强度、断裂伸长率、水蒸汽透过率及阻氧性,并将其应用于生鲜鱼片保鲜包装,测定了储藏期内鱼肉的p H、挥发性盐基氮（TVB-N）值和菌落总数。结果表明,KGM/EC复合膜拉伸强度随五倍子水提物添加量的增大而显著降低,当五倍子水提物添加量大于15%时,其拉伸强度无显著变化（p<0.05）。随着五倍子水提物添加量从0%增加至20%时,复合膜断裂伸长率显著性增加且水蒸汽透过率显著性降低（p<0.05）,另外,膜的阻氧性显著性提高（p<0.05）。采用添加20%五倍子提取物的复合膜（w/w）用于鱼片冷藏包装,鱼片保鲜的主要参考指标（p H、TVB-N值和菌落总数）与未用膜包装组和未添加五倍子复合膜组相比,均有显著性差异（p<0.05）。以菌落总数为参考指标,添加20%五倍子含量的复合膜包装的鱼片与未用膜包装鱼片相比,其4℃储藏条件下货架期延长了3 d。魔芋葡甘聚糖-乙基纤维素复合抗菌膜在食品保鲜上具有一定的应用前景。      

Miniaturization of cellulose fibers and effect of addition on the mechanical and barrier properties of hydroxypropyl methylcellulose films

Cellulose fibers were miniaturized by microfluidics technology to decrease their size and incorporated in hydroxypropyl methylcellulose (HPMC) films to study the effect of addition of such fibers on the mechanical and barrier properties of HPMC films suitable for application in food packaging. The particle size of fibers and the mechanical properties, water vapor and oxygen permeabilities, total pore volume, and light and electron microscopy micrographs of films were analyzed. Incorporation of cellulose fibers in the films improved their mechanical and barrier properties significantly. This study is the first to investigate the use of microfluidics technology for the purpose of decreasing the size of cellulose fibers and the addition of reduced size microfibers to improve physical properties of HPMC films.     

食品包装塑料薄膜的机械性能及检测方法研究

柔软的塑料薄膜适用于各种各样的包装,食品包装材料的机械性能是产品在包装之后对产品进行保护的最基本性能,可以防止包装的破损与泄漏。本文阐述了食品包装塑料薄膜的主要机械性能,包括拉伸性能、剥离性能、热合性能、撕裂性能、冲击性能以及穿刺性能,并介绍了主要的食品包装塑料薄膜的机械性能检测方法,为食品包装技术的研究和新产品的开发提供参考。