Physicochemical,Water Vapor Barrier and Mechanical Properties of Corn Starch and Chitosan Composite Films

Biodegradable flexible films were developed from corn starch (CS) and chitosan (CH); their microstructure, mechanical and barrier properties were evaluated. Chitosan and starch blend filmogenic suspensions showed a pseudoplastic behavior, similar to that of chitosan solutions. Smooth surfaces, homogeneous and compact film structures were observed from microstructure studies using scanning electron microscopy (SEM). The addition of glycerol reduced film opacity and increased film solubility of both CS and composite CS‐CH films. Water vapor permeability values of composite CS‐CH films plasticized with glycerol ranged between 3.76 and 4.54× 10⁻¹¹ g s⁻¹ m⁻¹ Pa⁻¹, lower than those of the single component films. CS‐CH films were resistant and their flexibility increased with glycerol addition. Tensile strength values of CS‐CH films were comparable to those of low‐density and high‐density polyethylenes but lower than that obtained for cellophane, however, composite biodegradable films showed lower elongation at break values than the synthetic commercial ones. In conclusion, CS‐CH films can be described as biofilms with a homogeneous matrix, stable structure and interesting water barrier and mechanical properties, with great possibilities of utilization, and with the advantage of biodegradability.     

Rice bran protein-based edible films

The development of degradable and edible films from protein sources has drawn significant attention for the utilisation of natural resources as well as for the alleviation of the environmental burden. Rice bran protein (RBP) was applied to protein film preparation in this study. The protein solutions were casted on plastic tissue culture dishes with glycerol as a plasticiser after heat treatment. Functional properties of the films were then measured. The puncture strength (PS) of RBP films increased up to pH 8.0 and then decreased. PS of protein films depends on the degree of protein purity, quality and composition. Higher concentration of glycerol weakened the films. The pH affected the water solubility of RBP films and the films showed least solubility at pH 3.0. RBP could be utilised in the preparation of degradable protein‐based films. The RBP‐based film had functional properties comparable to those of the soy protein‐based ones.     

Production and characterization of oxidized cassava starch (Manihot esculenta Crantz) biodegradable films

Plastic is one of the most common pollutants in the environment. Therefore, the number of studies on the use of biodegradable packaging is increasing. Starch is the primary material used in the production of biodegradable plastics due to its natural abundance and high biodegradability. Yet, the strong hydrophilic character of starch presents a challenge. Therefore, the modification of its structure through oxidation may yield interesting results as the viscosity reduction. The objectives of this work were to obtain cassava (Manihot esculenta Crantz) starch oxidized with 0.8 and 2.0% active chlorine, to develop biodegradable films and characterize their mechanical properties, solubility in water, permeability to water vapor, degree of swelling, and sorption isotherms. Biodegradable films were produced with starch concentrations of 2, 3, 4, and 5% w/w and 25% glycerol (g/100 g starch) added as a plasticizer. Images of the films were obtained with an atomic force microscope and allow to observe a smooth surface and the absence of starch granules in the film produced with oxidized starches. The tensile strength of the biodegradable film produced with oxidized starch (0.8% active chlorine) was 80 MPa. The value of permeability to water vapor was 1.613 × 10⁻⁹ kg/day/m/Pa, and the average solubility was 41%. The sorption isotherms showed that biodegradable films made with oxidized starches cannot be used in environments with relative humidity below 35% or above 90%.     

Trout skin gelatin-based edible film development

Edible biopolymer films were developed from gelatin extracted from trout skin (TSG) using thermal protein denaturation conditions and plasticizer (glycerol) concentration as variables. The amino acid composition of the TSG, elastic modulus, viscous modulus, and the viscosity of film-forming solutions, and tensile properties, water vapor permeability, solubility in water, and color of TSG-based films were determined. A 6.8% (w/w, wet basis) trout skin-extracted gelatin solution containing 9, 17, or 23% (w/w, dry basis) glycerol was heated at 80, 90, or 100 °C for 30, 45, or 60 min to prepare a film-forming solution. TSG can be characterized as a gelatin containing high contents of methionine and aspartic acid. The gelation temperature of the film-forming solution was 7 °C and the solution was subjected to heating to form a stable matrix for a film. Increased heating time of the film-forming solution reduced the film solubility (P < 0.05). Heating at 90 °C for 30 min was suggested as the requirement for film formation. As the concentration of glycerol in the film increased, film strength and moisture barrier properties decreased, while film stretchability increased (P < 0.05). Trout skin by-products can be used as a natural protein source for fabricating biopolymer films stable at ambient conditions with certain physical and moisture barrier properties by controlling thermal treatment conditions and glycerol concentrations. Practical Application: The fishing industry produces a significant amount of waste, including fish skin, due to fish processing. Trout skin waste has potential value as a protein source that can be used to form biopolymer edible films for packaging low and intermediate water activity food products, and thus may have practical applications in the food industry, which could be one way to cut waste disposal in the trout processing industry.     

Effect of Filler Content of Chemically Treated Short Bagasse Fiber-Reinforced Cardanol Polymer Composites

In this work, the sugarcane bagasse fiber was used as a filler to make a new type of biodegradable composite, using the cardanol resin, as a fully biodegradable thermosetting polymer matrix. Biocomposite performance was improved by chemically modified bagasse fiber using alkaline treatment. Two sets of composites were prepared with a fiber length of 10 and 20 mm with various weight percentages viz., 0, 5, 10, 15, and 20 of cardanol resin using a compression molding machine. The mechanical properties were studied using some tests and the morphological study in flexural fractured specimens was carried out using SEM. The thermal properties of biodegradable polymer composites were evaluated using TGA. The chemical formation of the new biocomposites was also examined by the FT-IR spectroscopy technique. The result proved that the morphology of the composites has improved the bonding between the fiber and resin, thus leading to enhancement of the mechanical properties. The result had shown the tensile and flexural strength with an increase in the range of bagasse fiber up to 15 wt% in both the sets. The TGA results showed that biocomposites of 15 wt% in both sets had the highest thermal stability. This investigation recommended the possibility of introducing bio-fiber obtained from waste agricultural residues in polymer matrix composites.     

4种改性淀粉与明胶共混膜的制备与性质比较

该研究对4种改性淀粉（羟丙基二淀粉磷酸酯、羟丙基淀粉、氧化淀粉、氧化羟丙基淀粉）的溶解度、膨胀势、糊化特性、老化值进行了分析和比较。溶解度高、膨胀势小、糊化特性好、老化值低的淀粉,较适宜作为制备共混膜的原料。在此基础上加入甘油或聚乙二醇400（Polyethylene Glycol,PEG400）作为增容剂,并对配方中水和甘油加入量进行了初步摸索,运用紫外、扫描电镜和拉伸试验机测定共混膜的透光性、透水气性、微观形貌和机械性能。结果表明：羟丙基淀粉溶解度最高,为86.42%;膨胀势最低,为0.086%,稳定性更好;黏度较低,老化值较大,流动性高,易于成膜。为4种改性淀粉中最适宜和明胶共混的原料。利用紫外分光光度计进行全波长扫描测量透光率;利用不同时间水保留质量反应透水汽性;用扫描电镜放大500~6 000倍对微观形貌观察,用拉伸材料试验机对机械性能进行测试。通过比较,发现以羟丙基淀粉为原料的共混膜,具有较好的透明度（优于纯明胶样品的透光度）,良好的透水汽性和机械性能。微观形貌也是呈现出相容性较好的形态（SEM显示）,相较于PEG400,甘油作为增容剂时共混膜的微观形貌横截面均匀光滑,内容物相容性好。明胶:甘油:水质量比为1:9:3:13制得共混膜透光性、透水气性、机械性能最佳,具有较好的实际应用价值。     

Preparation and properties of rice starch–chitosan blend biodegradable film

Biodegradable blend films from rice starch–chitosan were developed by casting film-solution on leveled trays. The influence of the ratio of starch and chitosan (2:1, 1.5:1, 1:1, and 0.5:1) on the mechanical properties, water barrier properties, and miscibility of biodegradable blend films was investigated. The biodegradable blend film from rice starch–chitosan showed an increase in tensile strength (TS), water vapor permeability (WVP), lighter color and yellowness and a decreasing elongation at the break (E), and film solubility (FS) after incorporation of chitosan. The introduction of chitosan increased the crystalline peak structure of starch film; however, too high chitosan concentration yielded phase separation between starch and chitosan. The amino group band of the chitosan molecule in the FTIR spectrum shifted from 1541.15 cm⁻¹ in the chitosan film to 1621.96 cm⁻¹ in the biodegradable blend films. These results pointed out that there was a molecular miscibility between these two components. The properties of rice starch–chitosan biodegradable blend film and selected biopolymer and synthetic polymer films were compared; the results demonstrated that rice starch–chitosan biodegradable blend film had mechanical properties similar to the other chitosan films. However, the water vapor permeability of rice starch–chitosan biodegradable blend film was characterized by relatively lower water vapor permeability than chitosan films but higher than polyolefin.     

Preparation and characterisation of films from xylose‐glycosylated peanut protein isolate powder

This work aimed at producing and characterising xylose‐glycosylated peanut protein isolate (PPI‐X) films by dissolving PPI‐X powder in water at ambient temperature and further plasticising with glycerol. The effect of powder dissolution temperature (20–100 °C) and glycerol concentration (15.0–45.0%, w/w) on mechanical properties and integrity of these films was quantified. The results showed that the powder dissolution temperature had no significant effect on the mechanical and water resistance properties of PPI‐X films within the temperature range tested. With increasing concentration of glycerol, the tensile strength and water resistance of PPI‐X films decreased and elongation increased. The films produced by dissolving the PPI‐X powder at 20 °C and plasticising with 25.0% glycerol had comparable mechanical properties and better water resistance compared to some other plant protein films plasticising with glycerol. The results suggested that PPI‐X films could potentially be used as biodegradable packaging materials.     

转谷氨酰胺酶(mTG)改性明胶可食性薄膜的制备

以转谷氨酰胺酶（mTG）改性明胶为基料、丙三醇为增塑剂制备可食性食品包装薄膜。研究了mTG、丙三醇的添加量以及膜的成型方法对产品的抗张强度、最大伸长率、韧性、水溶性、吸水性等物理机械性能的影响；筛选出了最佳工艺条件。     

Effect of Chitosan Nanoparticles and Pectin Content on Mechanical Properties and Water Vapor Permeability of Banana Puree Films

Abstract: Puree prepared from over‐ripe peeled bananas was used as raw material for films processing in a laboratory padder. Pectin and glycerol as plasticizer were added in small concentrations and chitosan nanoparticles (88.79 ± 0.42 nm medium size) incorporated at 0.2% (dry weight basis) as reinforcement material. The mechanical properties, water vapor transmission, thermal stability, and scanning electron microscopy of fractured film surfaces were characterized. Both pectin and glycerol demonstrated an important role in promoting elongation and film handability as was expected. The incorporation of nanoparticles promoted noticeable improvement of the mechanical properties and acted in reducing the water vapor permeation rate, by 21% for films processed with pectin and up to 38% for films processed without pectin, when compared to the control (puree films with no pectin and nanoparticles additions). Microscopic observation revealed a denser matrix when nanoparticles are incorporated into the films. Practical Application: The development of films from fruit purees head to a new strategy for plastic processing from natural resources. The over‐ripe or even waste banana can be adequately prepared for batch films processed with reasonable mechanical and barrier properties, suitable for applications in the food segment. The addition of small fractions of chitosan nanoparticles, form nanocomposites enhancing mechanical and thermal stability broadening potential film applications.     

Effect of banana and plasticizer types on mechanical,water barrier,and heat sealability of plasticized banana‐based films

Unripe banana flour and starch were used to formulate plasticized banana‐based films (flour film, PBF; starch film, PBS) with two types of plasticizers (glycerol, Gly; sorbitol, Sor) and a mixture of Gly‐Sor on film properties. PBS showed greater water barrier, elongation at break, toughness, and transparency, but lower efficiency in heat sealability than PBF. However, the easier and a higher yield in the preparation process of PBF lead to higher UV and visible light barrier than PBS which could be due to its protein content and the presence of phenolic compounds in PBF. Both banana films plasticized with Sor showed high glossiness, high efficiency in heat sealability, and mechanical and water barrier properties; however, the undesirable recrystallization of white crystals resulted in lower film flexibility. Thus, Gly‐Sor was preferred without change of water barrier but strengthened heat sealability. Therefore, banana‐based film might be considered as a green food packaging material.

Practical applications

Banana flour and starch from unripe bananas can be used as safe food ingredients for food products and as green biodegradable packaging materials. Banana flour film showed similar mechanical properties as banana starch film but involved easier processing and higher yield in the preparation of banana flour. Moreover, banana flour films had higher efficiency in heat sealability with the potential to protect the packed food from UV–visible light deterioration. Furthermore, an easier way to modify proper film properties is by the proper selection of the plasticizer. A mixture of plasticizers (glycerol and sorbitol) showed high potential to improve long‐term physical stability such as through UV–visible light prevention, and improved mechanical properties and heat sealability of plasticized banana‐based films. Briefly, plasticized banana flour film with a mixture of plasticizer will be potential, alternative biodegradable packaging material to reduce the use of nonbiodegradable synthetic plastic materials in food applications.     

Physical and Mechanical Properties of Pea-Protein-based Edible Films

ABSTRACT: Edible films produced from denatured pea protein concentrate (PPC) solution possessed the strength and elasticity to resist handling. Increasing the concentration of the plasticizer (glycerol) in the film decreased tensile strength and elastic modulus, and increased elongation and water vapor permeability (WVP). Very strong and stretch-able films were obtained from 70/30 and 60/40 of PPC/glycerol composition, respectively. The low WVP value was maintained over a range of glycerol concentration from 20% to 40%, in the dry film. Film solubility was not affected significantly by the amount of the plasticizer. The physical and mechanical properties of the PPC films were comparable with those of soy protein and whey protein films.     

Characterization of biodegradable films prepared with hake proteins and thyme oil

Hake protein biodegradable films containing different thyme oil levels (0.025, 0.05, 0.1 and 0.25 ml oil/g protein) were prepared and their physical, mechanical and antioxidant properties were studied. Dried proteins were solubilized at pH 11 with NaOH and glycerol (59% of protein content) was added as plasticizer.The addition of thyme oil levels reduced both the film thickness and water vapor permeability. Films were homogeneous and transparent with a yellowish color. The optical properties of films were not generally affected by the thyme oil addition. Any clear trend between the mechanical properties of biodegradable films and thyme oil added was observed. Hake protein films exhibited some antioxidant activity, which was improved by the addition of 0.25 ml of thyme oil/g of protein.     

Effect of Plasticizers on Mechanical and Barrier Properties of Rice Starch Film

The effect of plasticizers, glycerol, sorbitol and poly(ethylene glycol) 400 (PEG 400), on mechanical and barrier properties of rice starch film has been investigated. Sorbitol‐ and glycerol‐plasticized starch films appeared homogeneous, clear, smooth, and contained less insoluble particles compared to unplasticized rice starch films. PEG 400 did not form plasticized films of suitable characteristics. The softness and stickiness of films improved with increasing concentrations of glycerol and sorbitol. In general, films plasticized with glycerol and sorbitol displayed a better solubility in water than unplasticized films, i.e. 35% (w/w) glycerol and 45% w/w (sorbitol) (optimum solubility). The tensile strength of films decreased especially in the high concentration regime of plasticizers, between 20–45% (w/w) of plasticizer/rice starch film. Through the entire concentration regime, the tensile strength of glycerol‐plasticized films was significantly lower than that of sorbitol‐plasticized films, but their elongation was larger. The water vapor transmission rate (WVTR) through plasticized films and the oxygen transmission rate (OTR) increased with glycerol and sorbitol concentrations, however, glycerol was revealed to be significantly more effective in reducing the tensile strength as well as increasing the WVTR and the OTR compared to sorbitol. With the higher tensile strength and the smaller OTR and WVTR, the 30% sorbitol‐plasticized film reveals an improved coating performance in terms of a reduction of coating failures.     

Effects of drying conditions on some physical properties of soy protein films

The influence of drying conditions (air temperature and relative humidity) on mechanical properties, solubility in water, and color of two kinds of soy protein isolate film: a commercial one (CSPI) and other obtained under laboratory conditions (LSPI) were evaluated using the response surface methodology (RSM). Soy protein films were prepared by casting using glycerol as plasticizer. The films were dried in a chamber with air circulation under controlled conditions of relative humidity (24%, 30%, 45%, 60%, 66%) and air temperature (34, 40, 55, 70, 76 °C). It was verified that mechanical properties of films made from LSPI and CSPI are influenced in a very different way by the drying conditions due to a diverse initial protein conformation in both materials, as was revealed by DSC and SDS–Page studies. The solubility of the LSPI film was affected by temperature and relative humidity, being lowest (～50%) for films obtained at high RH and temperatures ranging from 45 to 76 °C. For CSPI films, in contrast, solubility did not depend on the drying process and it remained relatively constant (～40%). The optimal drying conditions determined by RSM were: 70 °C and 30% RH for CSPI films and 60 °C and 60% RH for LSPI films. Dried under these conditions, CSPI films presented a higher tensile strength, lower elongation at break, lower solubility and better water and oxygen permeability than LSPI ones.     

Bioplastics of Native Starches Reinforced with Passion Fruit Peel

Industrial passion fruit juice production generates a large amount of passion fruit waste, which contains about 60% of fibers when dried and could be used as reinforcement of thermoplastic starch. This study aimed to develop an extruded starchy bioplastic reinforced with passion fruit peel (Pfp) (0, 4, 10, 16, and 20%), glycerol (60, 64, 70, 76, and 80 wt%), and starch mix (55% corn and 45% cassava) that were processed at varied screw speeds (66, 80, 100, 120, and 134 rpm). The response surface methodology was applied to analyze the effects of Pfp, glycerol, and screw speed. Mechanical properties, contact angle, and water permeability and solubility were the response variables. Addition of Pfp, up to 4%, improved the bioplastic mechanical properties. High addition of Pfp (16 and 20%) combined with the lowest screw speed (66 rpm) reduced bioplastic water solubility. Water vapor permeability slightly increased with the combination of increasing glycerol content and screw speed. Contact angle was not statically affected by the independent variables. The extrusion showed as an interesting tool that provided greater homogeneity of Pfp incorporated in starch bioplastic, though the mix would benefit from finer Pfp particle size distribution.     

Oxidized banana starch–polyvinyl alcohol film: Partial characterization

Composites of polyvinyl alcohol, native banana starch, oxidized banana starch using glycerol like plasticizer, were studied by mechanical tests (MT), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC) and solubility in water. The oxidized banana starch showed higher level of carboxyl groups than of carbonyl groups. Composites of native banana starch/polyvinyl alcohol and oxidized banana starch/polyvinyl alcohol showed irregularities, indicating incomplete dispersion of the polymers. However, the film elaborated with the blend oxidized banana starch/polyvinyl alcohol showed the highest mechanical properties and the melting temperature of the first transition, as well as the lowest water vapor permeability, indicating higher interaction between both polymers. The composite oxidized banana starch/polyvinyl alcohol showed higher water solubility than the one of its counterpart with native banana starch at 25°C, and similar values were obtained for both films at 60°C. The oxidation of banana starch in order to elaborate a film blended with polyvinyl alcohol improved some mechanical and barrier properties, and this composite could be used for specific applications in the packing of food.     

Physico-mechanical and microstructural properties of semolina flour films as influenced by different sorbitol/glycerol concentrations

This study aimed at investigating the physico-mechanical and microstructural properties of a novel edible film based on plasticized semolina flour with different plasticizer (sorbitol/glycerol, 3:1) contents (30, 40, and 50%, w/w). As plasticizer content increased, water vapor and oxygen permeability, tensile strength, and the elastic modulus of the semolina films decreased, while their water solubility, moisture content, and elongation-at-break increased significantly (p < 0.05). Semolina-based films exhibited excellent absorption of ultraviolet light, and the addition of plasticizers improved the optical properties of the resultant films. Fourier-transform infrared spectroscopy showed no significant effect on the structure of the protein. Thermogravimetric analysis also revealed that increasing plasticizer concentration has no remarkable influence on the magnitude of weight loss. Atomic force microscopy images showed that the surface roughness of the films was influenced by plasticizer concentrations. This study demonstrated that semolina flour protein has the potential to prepare edible films.     

麦麸纤维/小麦麸质蛋白复合膜碱性乙醇成膜体系影响因素研究

将小麦麸质蛋白(wheat gluten,WG)和麦麸纤维(wheat-bran cellulose,WC)通过溶液共混于碱性乙醇系统,采用流延成膜法制备复合膜。探讨成膜体系中料液比、麦麸纤维含量、甘油添加量、乙醇浓度、体系pH值及黄原胶添加量对复合膜物理性能抗拉强度(tensile strength,TS)、断裂伸长率(elongation at break,EAB)、水蒸气透过系数(water vapor permeability,WVP)、水溶性和透光性等的影响。结果表明:添加麦麸纤维能明显增强小麦麸质蛋白膜的抗拉强度,降低其水蒸气透过系数和水溶性,抗拉强度最高为20.44 MPa,比纯小麦麸质蛋白膜(TS=8.65 MPa)提高了140%;成膜体系各因素对复合膜各物理性能都存在不同程度的影响,其中甘油添加量影响最大,其次为麦麸纤维含量,黄原胶添加量影响最小。该研究可为进一步制备性能优异的小麦麸质蛋白复合膜提供技术参考。     

Effect of glycerol and corn oil on physicochemical properties of polysaccharide films - A comparative study

The aim of this work was to evaluate the influence of glycerol and corn oil on physicochemical properties of polysaccharide-based films. The polysaccharides used were galactomannan from Gleditsia triacanthos and chitosan. Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis were performed, together with determinations of moisture content, solubility, water vapor permeability and mechanical properties. Structure-properties relationships were established, relating the two polysaccharides’ structures with the way they interact with water, other film’s constituents (glycerol and oil) and the resulting properties. The presence of glycerol and corn oil originated a more hydrophilic structure and a decreased affinity of the film matrix to water, respectively, in both polysaccharides. However, the two polysaccharides presented different behaviors in terms of glass transition temperature, water vapor permeability and elongation-at-break that have been related with the particularities of their structure: while for the galactomannan the specific sorption sites for water are the O-H groups, for chitosan those are O-H and/or NH₂ groups.The present work provides insight regarding the physicochemical properties of polysaccharide-based films and established relationships with polymers’ structure, showing that the two polysaccharides studied here have adequate properties to be used as packaging materials for specific food applications.