Films Prepared with Oxidized Banana Starch: Mechanical and Barrier Properties

Films were prepared using oxidized banana starch and glycerol. Oxidized banana starch was synthesized at three oxidation levels (0.5, 1.0 and 1.5% of active chlorine). Thermal gelatinization and casting were used for film preparation. Tensile strength, elongation, X‐ray diffraction pattern and water vapor permeability were tested. The tensile strength of the films was higher when the oxidation level of the banana starch was higher. When films were stored for 30 and 60 days, there were no statistical differences in tensile strength. However, differences occurred when those films were compared with the films stored for 90 days. The film with added sunflower oil presented the lowest value of elongation at 30 and 60 days of storage. When elongation values were assessed at 90 days of storage no statistical differences (α=0.05) were found among the films prepared from native starch with added sunflower oil, oxidized banana starch with 1.0% and oxidized banana starch with 1.5% oxidation level. All films had a B‐type X‐ray pattern. When the oxidation level in the starch increased, the peaks of crystallinity of the films increased as well. An additive effect was shown due to the higher interactions among polymer chains and among polymer and glycerol molecules as determined by the mechanical properties of the films analyzed. The corrected water vapor permeability (WVP_c) of the films stored for 30 and 60 days did not show statistical differences (α=0.05). The films prepared with oxidized banana starch had the highest WVP_c and those values increased when the oxidation level in the starch was higher. Oxidized banana starch can be used for preparation of films with adequate physicochemical characteristics.     

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.     

柠檬酸改性聚乙烯醇淀粉复合膜的结构及性能研究

为了改善聚乙烯醇淀粉膜的抗菌性能,采用流延法制备了不同质量分数的柠檬酸改性聚乙烯醇淀粉复合膜,通过XRD、FTIR、SEM等方法分析测试了复合膜的微观组织结构及性能.结果表明,添加柠檬酸并未改变复合膜的晶型结构,当柠檬酸含量在4％以上时膜层晶态衍射峰的强度显著增强.改性后的复合膜具有更加均匀平整的表面状态,同时膜层的断...     

Physicochemical Properties of Oxidized Cassava Starch Prepared under Various Alkalinity Levels

The physicochemical properties of hypochlorite‐oxidized cassava starch as influenced by the alkalinity levels (pH 8 to 11) during modification process were investigated. Hypochlorite oxidation generally increased the contents of carbonyl and carboxyl groups in starch but decreased starch viscosity. The formation of carbonyl and carboxyl groups was more favorable under the milder alkaline conditions (pH 8 and 9). Oxidation conducted at higher alkalinity levels produced both functional groups at a much slower rate and to a lesser extent. Starch viscosity decreased markedly with increasing reaction time. The alkalinity levels during the modification process greatly influenced the initial viscosity of the oxidized starch paste and the viscosity stability of the paste during storage. Thermal behavior studies by differential scanning calorimetry (DSC) demonstrated that oxidation decreased both gelatinization temperature and enthalpy. The decrease in gelatinization temperature was strongly related to the carboxyl group content. The more carboxyl groups the oxidized starch contained, the lower was the gelatinization temperature. Retrogradation of amylopectin tended to increase slightly after oxidation. While the light transmittance of native starch paste drastically decreased during cold storage, the changes observed in oxidized starch pastes were less pronounced and appeared to depend on carboxyl content. The results from light transmittance studies suggested that carboxyl groups introduced into the starch molecules could effectively prevent retrogradation.     

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%.     

Resistant Starch‐rich Powders Prepared by Autoclaving of Native and Lintnerized Banana Starch: Partial Characterization

Powdered preparations enriched in resistant starch (RS) were obtained from native and lintnerized (prolonged acid treatment) banana starches by consecutive autoclaving/cooling treatments. The preparations were tested for indigestible starch content, swelling and solubility properties, thermal analysis and pasting profile. The autoclaved samples had higher RS content than their parental counterparts, but the chemical modification (lintnerization process) allowed development of higher RS proportions (19%, dry matter basis, dmb). The autoclaved samples (RS‐enriched products) showed similar swelling values (α = 0.05) at the temperatures assessed. These RS‐rich products exhibited a lower solubility in water than the corresponding raw materials. The peak temperatures of the thermal transition were 155.5 and 145.8°C for native autoclaved and lintnerized autoclaved starch, respectively. These values indicate that RS products have a marked thermal stability. The pasting behavior of the RS products was less pronounced than that of the raw counterparts. Hence, their potential use as processed food ingredients should not impact final product viscosity. These RS‐enriched products appear suitable for the formulation of functional foods.     

Structural and physicochemical properties of banana resistant starch from four cultivars

Resistant starches were isolated from four banana cultivars: Musa AAA Cavendish, Musa ABB Bluggoe, Musa ABB Pisan Awak, and Musa AA Pisang mas. The structural and physicochemical properties of banana resistant starches were studied. Results showed that the particle size and shape of four banana resistant starches were different. Cavendish and Bluggoe banana resistant starch had a C-type crystalline structure, whereas Pisan Awak and Pisang mas had a B-type. The water-holding capacity of Pisang mas was the maximum. The solubility of Pisan Awak and Pisang mas was higher as compared to Cavendish and Bluggoe. The transparency of Cavendish banana resistant starch was the highest. More amylose was observed in Bluggoe and Pisan Awak banana resistant starch, whereas more amylopectin was observed in Cavendish and Pisang mas banana resistant starch. The initial pasting temperatures of Cavendish and Bluggoe banana resistant starches were higher as compared to Pisan Awak and Pisang mas banana resistant starch. The peak viscosity of Cavendish banana resistant starch was the highest in these four samples. The heat stability of Bluggoe banana resistant starch was the best one in the four banana resistant starches. The retrogradation was hard in the case of Bluggoe and Pisan Awak banana resistant starch. In conclusion, the properties of the four banana resistant starch samples were not the same, indicating that these could be used in different food products.     

Physicochemical and structural characteristics of cross‐linked banana starch using three cross‐linking reagents

Banana starch was cross‐linked using different cross‐linking reagents, phosphoryl chloride (POCl₃), sodium trimetaphosphate (STMP), and epichlorohydrin (ECH), under alkaline conditions. The reaction conditions were selected to produce similar pasting profiles. The effects of the different cross‐linking reagents on the physicochemical and structural characteristics of cross‐linked starches were evaluated. The microscopy study did not show difference on the surface of the granules. Slight decrease in the peak temperature and enthalpy were found in the cross‐linked banana starch. The chemical groups introduced in the starch molecules by the diverse reagents promoted the re‐association of starch chains during storage. The rheological analysis of all starch dispersion at 10% (flow curves) showed a non‐Newtonian shear‐thinning; pastes obtained were time‐independent, suggesting an important contribution of the continuous phase. Structural study showed that the cross‐linked STMP‐starch had the lowest level of amylose and the ratio short/long amylopectin chains. The three reagents used for cross‐linking presented different action mode on starch granule and its components.     

乙酰化香蕉淀粉的特性

通过与玉米淀粉比较,乙酰化香蕉淀粉的灰分、蛋白质、脂肪含量均比乙酰化玉米淀粉高.乙酰化香蕉淀粉糊的透明率在低温下出现较小的退化趋势,但常温下淀粉糊的透明率较高且有较好的稳定性.在较高温度下,乙酰化香蕉淀粉的持水能力比原淀粉高.乙酰化作用增加淀粉的溶解度和膨胀率.乙酰化作用也增加了香蕉淀粉糊的粘度值.     

Extrusion of banana starch: characterization of the extrudates

Extrusion of banana starch was carried out for obtaining extrudates with functional and digestibility characteristics. Experimental design with temperature, screw speed and moisture content as independent variables produced 20 experiments that were studied using response surface methodology to discover the effect of these variables on resistant starch content, water absorption index and water solubility index. The amylose content was 37.4% with high resistant starch (RS) content in the ungelatinized sample, which decreased when banana starch was gelatinized (1.9%). Extrudate samples had a higher RS content than the gelatinized native starch, showing that the extrusion process increased RS content of native starch due to starch depolymerization and during cooling of extrudates those linear chains form an arrangement that cannot be hydrolyzed by α‐amylase. The response surface regression model fitted to experimental results of resistant starch showed good determination coefficient (84%). During model validation for RS, the model explains the experimental results up to 90%. Response surface showed that water absorption index values were high when the temperature, moisture content and screw speed were also high; water solubility values were not affected by screw speed, and both temperature and moisture content had a quadratic effect. Cylindrical structures were observed in powders where RS was present and as RS level increased the cylinders became coarser. Copyright © 2006 Society of Chemical Industry     

茜素-马铃薯淀粉复合膜的制备及其氨响应行为研究

目的 探究茜素的加入对马铃薯淀粉基复合膜理化性质的影响,并评估其氨响应行为。方法 以马铃薯淀粉为成膜基质,通过流延法制备淀粉基生物薄膜,并在其内部嵌入天然色素—茜素,制备茜素-马铃薯淀粉复合膜,通过紫外可见吸收光谱、傅里叶红外光谱等对复合膜的结构进行表征。结果 实验表明,添加3 mg/mL的茜素对复合膜的厚度、含水量、水接触角、化学和晶体结构均无明显影响,但显著改善了复合膜的光阻隔性能、拉伸强度、断裂伸长率和热稳定性。在实验室12 W LED T8节能灯正常发光条件下,复合膜对2500 mg/L的氨水表现出肉眼可见的由黄色到紫色的颜色转变,且茜素-马铃薯淀粉复合膜的氨响应行为在循环利用4次后并未表现出衰减。结论 茜素可有效改善马铃薯淀粉基复合膜的理化性能,并使复合膜表现出良好的氨响应行为,有潜力应用于高蛋白食品新鲜度的日光下可视化检测。     

月桂酸酯化淀粉/聚乙烯醇(PVA)共混膜的制备及其性质研究

本文将原玉米淀粉和制备的月桂酸酯化淀粉与聚乙烯醇(PVA)共混,延流法制备淀粉/PVA共混膜,对膜的部分结构和性质进行研究,探讨月桂酸酯化改性对共混膜的性质和结构的影响。结果表明：酯化淀粉共混膜的表面比原淀粉更平滑,酯化改性提高了淀粉与PVA的相容性,使得透明度增大,断裂伸长率增加;但酯化改性对淀粉耐水性的改善不显著;抗拉伸强度改善不显著;热重分析结果表明酯化淀粉共混膜与原淀粉共混膜相比,其热分解更不完全。     

Adhesion and protective properties of polyvinyl alcohol nanofibrous composite fabrics

To avoid the separation of nanofiber mats and substrates during post-processing, the substrate was pretreated by plasma before electrospinning. Polyvinyl alcohol (PVA) nanofiber mats were deposited on the habutae, polyester-taffeta, and nylon-taffeta fabrics by a needless electrospinning setup with spiral disk spinnerets. The effects of plasma treatment on the adhesion of electrospun PVA nanofibrous composite fabrics were studied. The aerosol particles protective performance and wearabilities were also investigated as a function of the thickness of electrospun PVA nanofiber mat. Results showed that the surface nanoscale concave–convex roughness of substrate fabric was formed after oxygen plasma treatment. The peeling strength and peeling energy increased with the increase in surface roughness in a limited range. The peeling energy of PVA/nylon-taffeta enhanced to 2.97 times when nylon-taffeta treated by oxygen plasma at 200 W for 3 min. The aerosol particle filtration efficiency enhanced with the increase in electrospinning time, and the quality factor of PVA/nylon-taffeta was the highest with electrospinning for 10 min. Simultaneously, the air permeability and the water vapor transmission rate of PVA/nylon-taffeta decreased with the increase in electrospinning time, whereas the drape coefficient increased.     

增强剂对大豆蛋白/聚乙烯醇复合薄膜性能的影响

以薄膜拉伸强度、断裂伸长率、透光率、吸水率为评价指标,通过隶属度函数综合评分方法,研究了增强剂对大豆蛋白/聚乙烯醇复合薄膜性能的影响。实验结果表明:与对照组相比,添加可溶性淀粉,薄膜吸水率显著降低,透光率明显增大,但薄膜拉伸强度和断裂伸长率略有减小;添加羧甲基纤维素钠（CMC-Na）,薄膜拉伸强度和吸水率明显增大,断裂伸长率明显减小,透光率几乎没有变化;加入明胶,薄膜的拉伸强度增大不明显,断裂伸长率和透光率均有显著提高,吸水率明显减小,当明胶浓度为0.200%时,薄膜综合性能最佳,拉伸强度为4.69MPa,断裂伸长率为45.65%,透光率为13.78%,吸水率为47.21%。