Development of starch-based peelable coating for edible packaging

This research characterised properties and stability of starch-based peelable coating film layers via mould dipping. Different ratios between rice starch (RS) and hydroxypropyl cassava starch (HS) containing agar blends were characterised for fluid rheology and properties of solid films. Layer-by-layer mould dipping in starch blend suspensions produced peelable shells. Rheology indicated that formability of thin-film layer on solid surface subsequently affected integrity of the shells. HS highly adsorbed water which plasticised matrices giving lower relaxation temperature (~10 °C) than RS and caused shrivelling and non-stable shell structures. RS increased crystallinity and non-homogeneity of films and reduced network flexibility and light transmission. IR spectra indicated modified hydrophobicity and hydrogen bonding of starch blends which governed water and oxygen permeability. Higher RS ratios significantly increased crystallinity which affected physical, mechanical and barrier properties during storage for three months. Findings indicated that HS provided flexibility and stability while RS improved formability of peeled shells.     

淀粉基抗菌食品包装膜的研究进展

随着全球环保意识的提升,以来源广、可再生、成本低的淀粉为原料制备的淀粉基抗菌包装膜取代传统石油基包装材料的研究受到了广泛的关注。淀粉基抗菌膜通常是以天然淀粉/改性淀粉为原料加入塑化剂和抑菌剂并经热加工制备,其中抑菌剂的性质是决定抗菌膜抑菌活性的关键因素。此外,淀粉基抗菌膜的制备方法和材料性能也受到抑菌剂的来源和性质的影响。本文综述了基于不同抑菌剂制备的淀粉基抗菌膜的材料性能和抑菌活性,并提出在未来仍需研究安全性高、材料性能好和抑菌能力强的淀粉基抗菌材料,以期为开发绿色环保、性能优异的淀粉聚合物基抗菌食品包装材料提供指导。     

Physical performance of biodegradable films intended for antimicrobial food packaging

Antimicrobial films were prepared by including enterocins to alginate, polyvinyl alcohol (PVOH), and zein films. The physical performance of the films was assessed by measuring color, microstructure (SEM), water vapor permeability (WVP), and tensile properties. All studied biopolymers showed poor WVP and limited tensile properties. PVOH showed the best performance exhibiting the lowest WVP values, higher tensile properties, and flexibility among studied biopolymers. SEM of antimicrobial films showed increased presence of voids and pores as a consequence of enterocin addition. However, changes in microstructure did not disturb WVP of films. Moreover, enterocin-containing films showed slight improvement compared to control films. Addition of enterocins to PVOH films had a plasticizing effect, by reducing its tensile strength and increasing the strain at break. The presence of enterocins had an important effect on tensile properties of zein films by significantly reducing its brittleness. Addition of enterocins, thus, proved not to disturb the physical performance of studied biopolymers. Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste. Practical Application: Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste.     

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.     

Liquid and vapour water transfer through whey protein/lipid emulsion films

BACKGROUND: Edible films and coatings based on protein/lipid combinations are among the new products being developed in order to reduce the use of plastic packaging polymers for food applications. This study was conducted to determine the effect of rapeseed oil on selected physicochemical properties of cast whey protein films. RESULTS: Films were cast from heated (80 °C for 30 min) aqueous solutions of whey protein isolate (WPI, 100 g kg^?1 of water) containing glycerol (50 g kg^?1 of WPI) as a plasticiser and different levels of added rapeseed oil (0, 1, 2, 3 and 4% w/w of WPI). Measurements of film microstructure, laser light‐scattering granulometry, differential scanning calorimetry, wetting properties and water vapour permeability (WVP) were made. The emulsion structure in the film suspension changed significantly during drying, with oil creaming and coalescence occurring. Increasing oil concentration led to a 2.5‐fold increase in surface hydrophobicity and decreases in WVP and denaturation temperature (T_max). CONCLUSION: Film structure and surface properties explain the moisture absorption and film swelling as a function of moisture level and time and consequently the WVP behaviour. Small amounts of rapeseed oil favourably affect the WVP of WPI films, particularly at higher humidities. Copyright © 2010 Society of Chemical Industry     

The effect of edible coatings and polymeric packaging films on the quality of minimally processed carrots

Minimally processed carrots have a short shelf‐life because of white blush formation (caused primarily by surface dehydration) and microbiological spoilage (caused mostly by lactic acid bacteria). The use of polymeric packaging films combined with edible coatings might have an additive or synergistic effect to extend the shelf‐life of minimally processed carrots because of the formation of a double barrier to gases and water vapour. A 3 × 3 factorial experiment using a polymeric packaging film of three different levels of permeability and a cellulose‐based edible coating (Nature Seal^®) at different concentrations was conducted on minimally processed carrots to investigate any possible synergistic effect over 12 days of storage at 10 °C. No such effect was found. The polymeric packaging film effectively prevented microbiological growth and spoilage but was unable to control white blush formation. On the other hand, the edible coating partially controlled white blush formation but enhanced microbiological spoilage. The polymeric packaging film functioned primarily as a gas barrier, whereas the edible coating probably functioned as a moisture barrier. White blush formation was found to be the most important shelf‐life determinant for minimally processed carrots. Copyright © 2003 Society of Chemical Industry     

纳米淀粉的制备及其在可食性薄膜中的应用研究进展

天然高分子基纳米复合薄膜不仅耗能低,缓解了合成材料的不可降解对生存环境的污染及原料日益枯竭的压力,而且实现了资源的可持续发展,由于纳米颗粒的增强作用,复合薄膜呈现出比常规可食性膜更独特、更优异的性质,具有价廉易得、可再生、污染小等特点。文章对国内外纳米淀粉的制备方法进行了综述,介绍了物理、化学等方法制备纳米淀粉的方法,简要阐述了其在纳米复合可食性膜中的应用,并对其改善天然高分子薄膜的性能的研究进展进行了归纳,以期为进一步研究新型纳米复合可食用膜提供依据。     

Preparation and mechanical properties of edible rapeseed protein films

Edible films were manufactured from rapeseed oil extraction residues. To prepare rapeseed protein (RP) films, various concentrations of plasticizers and emulsifiers were incorporated into the preparation of a film-forming solution. The optimal conditions for the preparation of the RP film were 2% sorbitol/0.5% sucrose as plasticizer and 1.5% polysorbate 20 as an emulsifier. In addition, RP blend films were prepared. Gelidium corneum or gelatin was added to improve the physical properties of the RP film, and the highest tensile strength value of the films was 53.45 MPa for the 3% RP/4% gelatin film. Our results suggest that the RP-gelatin blend film is suitable for applications in food packaging. PRACTICAL APPLICATION: Edible RP films prepared in the present investigation can be applied in food packaging.     

Whey protein-okra polysaccharide fraction blend edible films: tensile properties, water vapor permeability and oxygen permeability

BACKGROUND: A hot‐buffer‐soluble‐solid fraction (HBSS) and an alkaline‐soluble‐solid fraction (ASS) of okra polysaccharides (OKP) were obtained using sequential extraction. These fractions were combined with whey protein isolate (WPI) and glycerol (Gly) plasticizer to form blend edible films. Effects of OKP fraction and content on tensile properties, water vapor permeability (WVP) and oxygen permeability (OP) were determined. RESULTS: HBSS film had significantly higher percent elongation (%E) and lower elastic modulus (EM), WVP and OP than ASS film. Increasing HBSS or ASS content in blend films with WPI significantly reduced film tensile strength and EM and increased film %E and WVP. OP values for WPI–HBSS blend films were significantly lower than OP for WPI or HBSS film. WPI–HBSS and WPI–ASS blend films had lower WVP and OP than WPI films with equivalent tensile properties. CONCLUSIONS: WPI–HBSS blend films have higher WVP and lower OP than WPI film or HBSS film, indicating unique interactions between WPI and HBSS. Compared to WPI film, WPI–HBSS blend films have improved flexibility, stretchability and oxygen barrier. Different HBSS and ASS compositions and structures are responsible for property differences between HBSS and ASS films and between WPI–HBSS and WPI–ASS blend films. Copyright © 2010 Society of Chemical Industry     

高直链玉米淀粉/羟丙基甲基纤维素可食性膜的制备及性能研究

以高直链玉米淀粉(HACS)和羟丙基甲基纤维素(HPMC)为主要成膜基材,采用溶液流延法制备了HACS/HPMC可食性膜。研究了不同配比的HACS与HPMC对可食性膜的结晶性能、力学性能、亲水性能和水蒸气阻隔性能等的影响。结果表明,随着HPMC比例的增大,HACS与HPMC之间的氢键作用减弱,复合膜的水溶性增大,连续相由HACS转变为HPMC,但HACS与HPMC的相容性变差。HPMC可有效降低可食性膜的结晶程度并抑制其在储藏过程中的老化。在复合膜中,当HACS与HPMC比例为8∶2时,可食性膜具有最大抗拉强度(7.5 MPa)、断裂伸长率(14.7%)、水接触角(84.33°)和最低水蒸气透过系数(2.17×10~(-10 )g·m·m~(-2)·s~(-1)·Pa~(-1))。纯HACS膜和纯HPMC膜的透光性能均优于HACS/HPMC复合膜。     

Nanofibre-based bilayer biopolymer films: enhancement of antioxidant activity and potential for food packaging application

This study aimed to enhance the antioxidant property of biopolymer film without the incorporation of external agents. The active bilayer film with improved antioxidant activity has been developed by electrospinning zein, a prolamine of corn as nanofibre (average diameter of 286 nm) on solvent cast chitosan film. Zein nanofibres exhibited a slight increase in antioxidant activity as compared to solvent cast zein film. But, zein nanofibre coating on chitosan films significantly improved its antioxidant activity from 12.41% to 44.17%. The developed bilayer films were evaluated for its ability to prevent browning in minimally processed apple slices and compared with those of chitosan and zein films plasticised with polyethylene glycol. Higher surface to volume ratio and better affinity of zein nanofibres in the bilayer film helped enhance its anti-browning ability. Thus, zein nanofibre-coated chitosan bilayer films can be used as an effective anti-browning packaging material for the packing of minimally processed fruits.     

Silk fibroin-based films in food packaging applications: A review

Plastic pollution is a significant concern nowadays due to wastes generated from non-biodegradable and non-renewable synthetic materials. In particular, most plastic food packaging material ends up in landfills, creating mass wastes that clog the drainage system and pollute the ocean. Thus, studies on various biopolymers have been promoted to replace synthetic polymers in food packaging and consequently, the high number of research in biopolymers food packaging, especially in the characterization, properties and also the development of the biopolymer. For biopolymer-based food packaging, silk fibroin (SF) has been highlighted because of its biodegradability and low water vapor permeability properties. This review focuses on the different properties of SF films prepared through solution casting and electrospinning for food packaging. Discussions encompassed chemical properties, mechanical properties, permeability, and biodegradability. This review also discussed the studies that used SF as the biomaterial for food packaging.     

Active packaging films and edible coatings based on polyphenol-rich propolis extract: A review

The development of active packaging films and edible coatings based on biopolymers and natural bioactive substances has received increasing attention in recent years. Propolis, also called bee glue, is a natural resin substance collected by worker-bees from the mucilage, gum, and resin of several plants. In food industry, propolis is commonly extracted in solvents to afford polyphenol-rich extract with potent antimicrobial and antioxidant activities. The prepared propolis extract can be mixed with biopolymers, plasticizers, emulsifiers, and reinforcing agents to develop active packaging films and edible coatings. The functionality of active packaging films and edible coatings is closely related to the type, harvesting method, geographic origin, extraction method and extraction conditions of propolis, the content and composition of polyphenolic compounds in the extract, and the presence of other bioactive substances. Active packaging films and edible coatings based on propolis extract can impact the physical, biochemical, and sensory properties of food (e.g., fruits, vegetables, meat, and fish) during storage. This review focuses on the recent advances of active packaging films and edible coatings based on polyphenol-rich propolis extract. The impact of polyphenol-rich propolis extract on the structural characterization, functionality, and potential food applications of the films and edible coatings is summarized.     

Active packaging of ground beef patties by edible zein films incorporated with partially purified lysozyme and Na2EDTA

In this study, antimicrobial activity of zein films incorporated with partially purified lysozyme and disodium ethylenediaminetetraacetic acid (Na₂EDTA) has been tested on selected pathogenic bacteria and refrigerated ground beef patties. The developed films containing 700 μg cm^?2 lysozyme and 300 μg cm^?2 Na₂EDTA showed antimicrobial activity on Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium. The application of lysozyme and Na₂EDTA incorporated zein films on beef patties significantly decreased total viable counts (TVC) and total coliform counts after 5 days of storage compared to those of control patties (P < 0.05). Zein films incorporated with lysozyme and Na₂EDTA or Na₂EDTA alone significantly slowed down the oxidative changes in patties during storage (P < 0.05). Redness indices of patties coated with zein films were significantly lower than those of uncoated control patties during storage (P < 0.05). This study demonstrated the potential usage of zein films containing lysozyme and Na₂EDTA for active packaging of refrigerated meat products.     

Edible packaging from hydroxypropyl thermoplastic cassava starch,agar and maltodextrin blends produced by cast extrusion

Edible packaging from hydroxypropyl cassava starch with different degrees of substitution (DS), agar and maltodextrin films was produced by conventional cast extrusion. Microstructures showed hydrophobic agar aggregates (100–200 µm) dispersed in film matrices, giving nonsmooth surfaces that enhanced wettability (17%–31%). Higher DS increased interaction between agar and maltodextrin via hydrogen bonding due to greater plasticisation and enhanced formation of agar networks. Lower DS starch showed instability with lower tensile strength (23% of higher DS), giving poor processability that was greatly improved by agar (20%). Water vapour and oxygen permeability depended on microstructures and hydrophilic–hydrophobic properties of the matrices which were decreased by 25% and 58% with combined agar and maltodextrin, respectively. Crystallinity of the films depended on plasticisation, with enhanced mobility that reduced transparency. Agar and maltodextrin inhibited recrystallisation of starch. Findings suggested that higher DS starch and agar enhanced extrusion processability, while maltodextrin increased plasticisation and reduced network strength.     

Development and characterization of cassava starch and soy protein concentrate based edible films

The sensory attributes, mechanical, water vapour permeability (WVP) and solubility properties of cassava starch and soy protein concentrate (SPC)‐based edible films of varying levels of glycerol were studied. Addition of SPC and glycerol up to 30% and 20%, respectively, reduced stickiness and improved colour and appearance of the films. Tensile strength (TS), elastic modulus (EM) and elongation at break (EAB) of films increased, while film solubility (FS) and WVP decreased with SPC and glycerol up to 50% and 20% level, respectively, ranging from 20.33 to 26.94 MPa (TS), 41.33 to 72.76 MPa (EM), 7.90 to 12.28 MPa (EAB), 15.07 to 31.90% (FS) and 2.62 to 4.13 g H₂O mm m^?2 day kPa (WVP). The TS, EAB and WVP were higher for the biofilms than for low‐density polyethylene and cellophane films.     

An absorption model for the thickness effect in hydrophilic films

The permeability parameters for moisture transmission through hydrophilic films are well known to be thickness dependent, this effect appearing in permeability studies based on diffusion models. In our model we assume that, besides diffusion, some of the water vapour of the diffusion flux is removed by the hydrophilic components of the films. This water is immobilized and becomes hydration water of the hydrophilic molecules. This paper describes a diffusion–adsorption model, with thickness‐independent parameters, which explains this phenomenon.