油酸与甘油对玉米醇溶蛋白膜机械性能的影响及机理探讨

主要研究了两种性质不同的增塑剂(油酸和甘油)对玉米醇溶蛋白(zein)膜机械性能的影响和可能的机理,以抗拉伸强度(TS)、伸长率(E)、透水率(WVP)为指标,结果发现油酸和甘油都能显著改善zein膜的机械性能,且添加量都以20%(g/g zein)最优;复合增塑研究发现,当添加20%混合增塑液对zein膜进行增塑时,以油酸∶甘油为3∶1复合增塑的效果最好,其中与未增塑的zein膜相比,TS提高190%,E提高70%。进一步统计学分析表明,油酸与甘油在对zein膜增塑时有正协同作用。对未增塑、20%油酸增塑、20%甘油增塑及20%复合增塑(油酸∶甘油为3∶1)zein膜的玻璃态转化温度(Tg)及红外光谱(FT-IR)分析发现,增塑后的zein膜Tg有所下降,其中复合增塑降幅最大;FT-IR图谱分析发现,复合增塑时甘油的特征峰向高波长方向移动,显示增塑作用加强;蛋白二级结构分析发现,复合增塑后,二级结构虽有小幅改变,但并未达到显著水平,因此增塑剂与zein之间的非共价键相互作用(疏水力和氢键)可能是其增塑的化学基础。     

可食性绿豆淀粉膜制作工艺的研究

以绿豆淀粉为主要材料,甘油作为增塑剂,羧甲基纤维素(CMC)作为增强剂,以可食性膜厚度、抗拉强度、断裂延伸率、阻水性为指标,研究了甘油添加量、CMC添加量、干燥温度、干燥时间等因素对可食性淀粉膜性能的影响。结果表明以绿豆淀粉为成膜主体,配以0.4 g/g淀粉的甘油和0.06 g/g淀粉的CMC,在80℃烘干4 h,得到淀粉膜的抗拉强度为9.51 MPa,延伸率为114.55%,水滴渗透时间(Ts)为240.98 min/mm。     

可食性花生分离蛋白膜的保藏性能研究

研究花生分离蛋白的成膜特性,对成膜液进行适当的加热和调节pH可以提高花生分离蛋白膜(PPI)的抗拉强度(TS)、降低水蒸气迁移速率(WVTR),并对樱桃涂膜保鲜进行了初步研究。对花生分离蛋白成膜特性的研究表明:花生分离蛋白经适当的碱处理和热处理可以改善其成膜特性,成膜溶液的浓度和干燥条件宜控制为6%和65℃、1.5h。适当的增塑剂(1.5%甘油)使膜具有一定的抗拉强度,且不会明显降低膜的阻湿性能;在所研究的2种增塑剂中,乙二醇的增塑效果较甘油明显。膜的厚度对膜的机械性能影响较小,但对阻湿性能影响较大。WVTR随厚度的增加而逐渐减少。     

增塑剂对壳聚糖-明胶复合膜物理性能的影响

研究了增塑剂(甘油、乙二醇、聚乙二醇400)对壳聚糖-明胶复合膜性能的影响.结果表明:增塑剂的加入对膜的物理性能产生了显著的影响,三种增塑剂都使膜的拉伸强度和吸水性降低、断裂伸长率和透水气率增大,但不同的增塑剂对断裂伸长率的影响表现出较大不同.甘油和乙二醇对膜的透光率影响不大,聚乙二醇400会使膜的透光率大大降低.综合各种指标,甘油对壳聚糖-明胶复合膜的增塑效果最好.     

辅增塑剂种类对淀粉/聚羟基脂肪酸酯复合膜性能的影响

以甘油(GLY)为主增塑剂,对辅增塑剂乙二醇(EG)、聚乙二醇200(PEG200)、聚乙二醇400(PEG400)、乙酰柠檬酸三正丁酯(ATBC)改善淀粉/聚羟基脂肪酸酯(PHA)复合膜的性能进行研究。结果表明:增塑体系EG/GLY所成膜具有较高的抗拉强度,增塑体系PEG200/GLY所成膜具有较高的断裂伸长率;增塑体系ATBC/GLY所成膜具有较好的阻水性;增塑体系PEG200/GLY和PEG400/GLY所成膜对O2和CO2的阻隔性较好,膜表面比较光亮,且前者具有较高的透光率;X-射线衍射(XRD)表明,辅增塑剂PEG200和PEG400的加入增大了膜的结晶度;扫描电镜(SEM)表明,增塑体系PEG200/GLY所成膜具有最均匀与平滑的微观结构;红外光谱(FTIR)表明,复合增塑体系的增塑效果优于GLY单一增塑。综合膜的各项性能得出,辅增塑剂PEG200和PEG400对淀粉、PHA有较好的增塑效果,且PEG200的增塑效果优于PEG400。     

可食性羧甲基纤维素膜制备及性能研究

该试验主要以羧甲基纤维素(CMC)为膜原料,研究影响膜性能的各种因素,并通过正交试验确定制备CMC可食性膜最佳工艺参数;最后通过验证试验得出制备可食性羧甲基纤维素膜最佳工艺条件为:CMC浓度为2%,甘油添加量为30%,倒膜量为11 g,烘烤温度为50℃;在此条件下制得膜综合评分为87.18分。     

SPI/MC关混可食膜的性能研究

研究了甲基纤维素(MC)对以甘油为增塑剂的大豆分离蛋白(SPI)膜物理性质的影响.结果表明:SPI膜的抗拉强度和表面疏水性随着MC添加量的增加而显著提高(P≤0.05),在添加量为20.0%(w/w,SPI)时相对于对照样分别提高了66.32%和25.39%;断裂伸长率随着MC添加量的增加而先增大后降低,在添加量为10.0%时最大;膜的透光率、水分含量、可溶性干物质总量和水蒸气透过系数随着MC添加量的增加而降低(P≤0.05),在添加量为20.0%时相对于对照样分别降低了41.58%、14.02%、26.55%和20.86%.     

可食性魔芋葡甘聚糖成膜特性研究

以魔芋胶 (KG)为基材 ,研究KG的浓度、增塑剂的种类与浓度和干燥温度等因素对膜的抗张强度 (TS)、耐破度 (BS)、伸长率 (E)以及水蒸气透过系数 (WVP)的影响。结果表明 ,随KG浓度的增大 ,各指标均有所升高 ,但浓度太高 (>10 g/L) ,制膜困难 ,且表观性状不够理想。综合考虑 ,浓度以 8g/L为宜 ;随增塑剂浓度的增加 ,膜的TS下降 ,E增大 ,阻湿性能明显降低 ;3种增塑剂中 ,甘油的增塑效果最明显 ,聚乙二醇 4 0 0次之 ,乙二醇最差 ;随干燥温度的提高 ,膜的TS有所增加 ,E和WVP有所降低 ,但温度太高 ,膜显微黄色 ,脆性增大 ,一般 60℃较为理想     

亲水性胶体降低油炸裹浆薯条含油量的研究

以冷冻薯条为原料,通过在天妇罗预拌粉中添加亲水性胶体甲基纤维素(Methylcellulose,MC),羟丙基甲基纤维素(Methylhydroxypropylcellulose,HPMC)及羧甲基纤维素钠(Carboxymethylcellulose sodium,CMC),配成面糊裹在冷冻薯条表面,使薯条在油炸过程中减少油脂摄入,进而降低样品中的油脂含量。结果显示:3种亲水胶体与对照组相比均有显著的减油效果,其中甲基纤维素(MC)效果最好,羧甲基纤维素钠(CMC)效果次之,羟丙基甲基纤维素(HPMC)效果最小,在质量分数为0.4%时减油率分别达到19.54%,14.58%,9.88%;选取减油效果较好的MC和CMC按照总质量分数0.4%进行不同比例(1∶9、2∶8、3∶7、4∶6、5∶5、6∶4、7∶3、8∶2、9∶1)的混合,研究二者混合后添加到裹浆层中对裹浆薯条油炸后含油量的影响。结果显示MC与CMC按照3∶7的比例复配后减油效果最好,0.4%的质量分数下减油率可达到31.24%。     

4 种改性方式对明胶膜性能的影响

研究了共混改性、增塑改性、交联改性和乳化改性对明胶膜性能的影响。结果表明,明胶分别与壳聚糖、海藻酸钠共混溶解性较好,成膜均匀透明,同时具有较低的水蒸气透过率和透氧率,阻隔性增强;添加甘油作为增塑剂可提高明胶膜的断裂伸长率,机械性能增强;与柠檬酸钠交联改性后降低了明胶膜的水蒸气透过率,增强阻隔性能,提高抗拉强度,增强力学性能,但是膜的透光率下降;添加质量分数为0.1%的乳化剂吐温-80可以降低可食膜的水蒸气透过率,增强膜的阻隔性能,同时增大抗拉强度,改善机械性能。研究认为,共混、增塑、交联、乳化4 种改性方式均能不同程度地影响明胶膜的阻隔性能和机械性能,改善明胶膜的综合性能以满足其在不同领域的应用。     

Permeability and Mechanical Properties of Cellulose-Based Edible Films

Factors affecting barrier properties [oxygen permeability (OP) and water vapor permeability (WVP)] and mechanical properties [tensile strength (TS) and elongation (E)] were investigated for methyl cellulose (MC) and hydroxypropyl cellulose (HPC) films. OP, WVP and TS of MC and HPC films increased as the molecular weight (MW) of the cellulose increased. E of MC films increased as MW increased, but E of HPC films was highest for the intermediate MW of 370,000. OP, WVP and TS of MC films were not a function of thickness, but E slowly increased as film thickness increased. OP and WVP of HPC films were not relatable to film thickness, but TS and E of HPC films slowly increased as film thickness increased. TS decreased and E increased for both film types as concentration of plasticizers was increased. Plasticizers enhanced or retarded OP and WVP of cellulose-based films, depending on their concentrations.     

THE EFFECTS of PLASTICIZERS ON CRYSTALLINITY, PERMEABILITY, and MECHANICAL PROPERTIES of METHYLCELLULOSE FILMS

The effects of plasticizers (polyethylene glycols [PEG] 400, 1,450, 8,000 and 20,000, glycerol [G] and propylene glycol [PG]), 30% dry basis, on the physical properties of methylcellulose (MC) films were investigated. With the exception of PG, plasticizers with low molecular weights (G and PEG 400) caused the largest increase in the d₁₀₁ spacing of the crystal lattice. All plasticizers significantly (α= 0.05) increased oxygen (O₂P) and water vapor permeabilities (WVP) of the films as compared to that of unplasticized MC, with PEG 400 having the greatest effect on O₂P and G having the greatest effect on WVP. With the exception of PG, all plasticizers decreased the tensile strength of MC films, with PEG 400 causing the largest decrease. With the exception of PG and PEG 400, all plasticizers increased percent elongation values of MC films, with PEG 1,450 having the greatest effect. Glycerol and PEG were the most effective plasticizers for MC. the higher molecular weight plasticizers do provide some plasticizing properties and may be more suitable for applications that require a lower permeability to water vapor than can be achieved with glycerol.     

羧甲基纤维素强化胶原纤维膜的制备及其性能分析

基于静电相互作用（离子键、范德华力）的蛋白质-多糖聚合现象成为改良可食膜的重要手段。本实验以酸溶胀胶原纤维（正电性）为基料,研究带负电性的羧甲基纤维素（carboxymethyl cellulose,CMC）对胶原纤维膜性能的影响。结果表明：当CMC添加量（以胶原纤维质量计,下同）过多（大于10%）,成膜液发生絮凝甚至分层现象而不能成膜;随着CMC添加量（范围为0%～5.0%）的增加,成膜液ζ-电势显著下降,pH值无明显变化,复合膜表面越来越粗糙,膜厚度增加,透光率显著降低（P＜0.05）;复合膜拉伸强度和杨氏模量随CMC添加量增加而显著增加（P＜0.05）,而断裂延伸率显著降低（P＜0.05）;当CMC添加量达5.0%时,复合膜的水蒸气透过率达到（32.41±0.86）g/（m·s·Pa）,阻氧性与膜溶胀动力学性能显著提高（P＜0.05）;此外,热稳定性分析表明添加CMC能够提高复合膜热稳定性。由此可知,CMC能够通过静电相互作用促进与胶原纤维的结合,提高胶原纤维膜相关机械强度和阻隔性能,从而为可食膜性能提升提供了一种可行手段。     

Preserving sensory attributes of roasted peanuts using edible coatings

Peanut products are susceptible to develop rancid and off‐flavours through lipid oxidation. Preservation of these products is one of the problems in the peanut industry. The purpose of this work was to determine the sensory and chemical stability of roasted peanuts (RP) coated with different edible coatings: carboxymethyl cellulose (RP‐CMC), methyl cellulose (RP‐MC) or whey protein (RP‐WPI) during storage. Sensory attributes and chemical indicators (peroxide and p‐anisidine values, and conjugated dienes) of lipid oxidation were measured during storage. Chemical indicator values and intensity ratings of oxidised and cardboard flavours had lower increase in RP‐CMC, RP‐MC and RP‐WPI during storage than in RP, whereas roasted peanutty flavour showed a lower decrease. The stability of RP‐CMC is about a double longer with respect to RP. These results indicate that edible coatings preserve the sensory properties of roasted peanuts. Carboxymethyl cellulose exhibited the best protecting effect on this product.     

Effects of plasticizers, pH and heating of film-forming solution on the properties of pea protein isolate films

Effects of glycerol (3-7% w/w) and sorbitol (4-8% w/w) concentration, pH (7.0, 9.0, 11.0) and heating (90 °C, 20 min) of film-forming solution (FFS) on the water vapor permeability (WVP), moisture content (MC), solubility, light transmission and transparency of pea protein isolate (PPI) films were investigated. Films plasticized with sorbitol exhibited significantly lower WVP, lower MC and higher solubility, in comparison with glycerol-plasticized films. Increasing glycerol content of the films led to increases in WVP and MC but did not affect film solubility. In contrast, increase in sorbitol content had no effect on permeability and MC but resulted in increased film solubility. Moisture sorption isotherms of PPI films suggested that the difference in WVP observed among films plasticized with glycerol and sorbitol might be due to the different hygroscopicity of these plasticizers. The pH of FFS did not have a significant effect on WVP and MC. Solubility of PPI films formed from non-heated FFS was not affected by pH, whereas solubility of films formed from heat-treated FFS generally increased when pH was increased from 7.0 to 11.0. Heating of FFS resulted in improved film transparency. All tested films were characterized by excellent ability to absorb UV radiation. Microstructural observation by scanning electron microscopy did not show differences between sorbitol- and glycerol-plasticized films.     

Physical properties of biopolymers containing natamycin and rosemary extract

Antifungal biopolymers were prepared by incorporating natamycin (NA) and NA + rosemary extract (RE) into wheat gluten (WG) and methyl cellulose (MC) films. Interaction between antimicrobial agents and biopolymers was determined with mid-infrared spectroscopy and scanning electron microscopy (SEM). Water vapour permeability and mechanical properties of these films were also measured. Mid-infrared spectroscopy did not indicate any interaction. SEM observations showed that NA crystallises at high concentrations in biopolymers. There were no significant changes in water vapour permeabilities of biopolymers containing active agents at P  < 0.05. While NA incorporation did not result in any changes in mechanical properties of WG films a reduction in tensile strength was observed for MC films containing high concentration of NA. In general, active agent incorporation into WG and MC films did not result in any considerable changes in their physical properties that could affect their application.     

Crystallization of High-Amylose Starch by the Addition of Plasticizers at Low and Intermediate Concentrations

ABSTRACT:  The antiplasticization effect of plasticizers (that is, polyols and monosaccharides) in starch films was investigated. Pea starch films were plasticized by various polyols and monosaccharides at the levels of 0% to 25% (w/w, plasticizer/starch). After 14 d of storage at 50% relative humidity, the crystallinity of pea starch films increased with increasing concentration of plasticizers from 0% to 20%. Accordingly, moisture content, water vapor permeability, oxygen permeability, and elongation decreased with increasing plasticizer concentration from 0% to 20%, showing the antiplasticization effect. The addition of plasticizers above 20% reduced the crystallinity of starch films, consequently showing the plasticization effect. The results showed that the addition of the plasticizers facilitated the crystallization of the polymer chains through the antiplasticization phenomenon at the concentration range below 15%. Above 20%, plasticizers performed the conventional plasticization effect. Each plasticizer had different critical concentration where the antiplasticization was converted to plasticization.     

Sorption isotherm and plasticization effect of moisture and plasticizers in pea starch film

Pea starch films were produced with various plasticizers (glucose, fructose, mannose, sorbitol, and glycerol). Effects of plasticizer content (4.34 to 10.87 mmol/g of dry starch) and storage relative humidity (RH) (11.3% to 75.4%) on moisture content (MC), tensile strength (TS), elongation (E), modulus of elasticity (EM), and water vapor permeability (WVP) were evaluated using response surface methodology. MC was influenced strongly by RH. Glycerol-plasticized films had the highest MC, indicating that water molecules played a more important role in plasticizing starch films. Monosaccharide-plasticized films and polyol-plasticized films had similar TS values. However, monosaccharide-plasticized films had higher E values and lower EM values than polyol-plasticized films, meaning monosaccharides had better efficiency in plasticizing starch films. Recrystallization happened in glucose- and sorbitol-plasticized films when they were stored in high RH. Sorption isotherm studies showed the similar adsorption and desorption profiles for all 3 monosaccharide-plasticized films and a hysteresis. The Flory-Huggius model fitted experimental data best for starch films, while the BET model fitted the data marginally.     

不同基材复配紫薯花青素制备智能指示膜及其应用

以马铃薯淀粉（starch,S）、羧甲基纤维素钠（carboxymethyl-cellulose sodium,CMC）以及魔芋葡甘露聚糖（konjac glucomannan,KMG）两两互配为成膜基材,紫薯花青素（P）作为新鲜度指示剂,制备智能指示膜,比较KMG/S/P（KSP）、S/CMC/P（SCP）、KMG/CMC/P（KCP）3 种智能指示膜的力学性能、水分质量分数、水溶性、微观结构、相容性及稳定性等的差异,并运用鱼肉进行初步应用评价。结果表明：SCP膜的抗拉伸强度最高（（15.39±1.15）MPa）、水溶性最低（（24.17±1.21）%）,且颜色稳定性好;而KCP膜断裂伸长率最大（（44.79±1.43）%）;扫描电子显微镜观察结果表明不同智能指示膜微观结构差异明显,其中SCP膜横切面光滑紧密。利用SCP检测鱼肉新鲜度,25 ℃下鱼肉贮藏24 h后挥发性盐基氮含量达15.2 mg/100 g,已经开始腐败,此时智能指示膜显示出浅红色,48 h后变为浅蓝色。因此,SCP膜适合新鲜度检测,且运用紫薯花青素开发稳定的指示膜有良好的应用前景。