有色废弃聚酯织物的丙三醇脱色

利用丙三醇溶剂对废旧聚酯织物进行脱色,以织物脱色前后的K/S值对脱色效果进行表征。研究了聚酯织物与丙三醇质量比、脱色温度和时间对脱色效果的影响,得到丙三醇对聚酯织物的脱色工艺为:聚酯织物与丙三醇质量比1:20、220℃脱色处理20 min,最高脱色率可达93.94%。对丙三醇进行回收利用,纯度约为86.03%。利用回收的丙三醇对废旧织物再次脱色,脱色率可达90.36%。     

发酵法生产工业级丙三醇中显“酸性”关键组分的研究

脂肪酸和脂肪酸酯是呈“酸性”的,它是使发酵法生产丙三醇的NaOH滴定值超标的一类杂质.为分析其产生来源及进一步提出控制策略,确定了显“酸性”的关键脂肪酸酯.GC－MS分析发现,发酵法生产工业级丙三醇中脂肪酸及脂肪酸酯为乙酸、丙酸、丁酸甘油酯及甘油单乙酸酯等,其中甘油单乙酸酯含量最高.HPLC法测定了不同厂家发酵生产的工业级丙三醇中甘油单乙酸酯的含量,一般在0.5～3.0g/100g丙三醇.它对工业级丙三醇的脂肪酸滴定值影响最大,是发酵法生产工业级丙三醇显“酸性”的关键物质.     

叶丝气流干燥过程中水分和丙三醇迁移特性

为了在叶丝气流干燥过程中有效调控物料的水分和丙三醇含量,考察丙三醇含量和干燥温度对叶丝中丙三醇和水分迁移的影响,利用固定床气流干燥装置,在100～145℃下对丙三醇含量为0～6.6%的叶丝进行干燥试验,得到了叶丝中丙三醇和水分释放规律。结果表明：(1)添加丙三醇后叶丝水分迁移规律基本一致,叶丝的干燥速率受丙三醇初始含量的影响较小。干燥过程分为两个阶段,第一阶段（0～100 s）和第二阶段（100～600 s）。(2)叶丝表面温度与干燥温度正相关,与丙三醇的初始含量无关。(3)丙三醇初始含量对其脱除无显著影响。第一阶段丙三醇的损失量基本相同,约占总损失量的50%以上;第二阶段不同丙三醇初始含量的损失速率无明显差异,且随着干燥时间的增加不断减小。(4)干燥温度对丙三醇脱除有显著影响。第一阶段不同干燥温度下丙三醇损失量均为0.6百分点左右,损失速率随干燥时间线性降低,损失速率的变化率与干燥温度呈负相关关系;第二阶段丙三醇损失量随干燥温度的升高而增大,损失速率基本保持稳定。     

叶面喷施丙三醇对烟叶碳氮代谢及硝酸盐积累的影响

  目的  探索丙三醇对白肋烟碳氮代谢及其硝酸盐积累的调控机理,建立新的白肋烟增效减害调控技术。  方法  以白肋烟品种TN90和TN86为材料,设置不同丙三醇浓度试验,并在确定丙三醇最佳适宜浓度的基础上,设置高氮和低氮两个处理,研究丙三醇对烟叶生物量积累、氮代谢关键酶活性、主要碳氮化合物含量及相关基因表达情况的影响。  结果  1）在高氮和低氮水平下,喷施丙三醇15 d后,烟叶生物量分别增加10.20%和13.36%,氮素积累量和氮素利用效率分别增加10.21%、3.15%、6.81%和3.11%,烟叶总糖和还原糖含量分别升高了25.15%、32.84%、47.76%和44.57%,但7 d后烟叶硝酸盐含量下降了53.22%和59.67%;2）低氮水平下喷施丙三醇烟叶色素、可溶性蛋白质和两糖含量与高氮条件下不喷施丙三醇结果相近;3）基因表达分析表明,喷施丙三醇显著促进了光反应途径、碳固定途径、蔗糖合成和氮代谢途径关键基因的表达,与对照相比,基因CP12-2、PPC16和NPF7.3的表达量增加0.5倍多。  结论  丙三醇能够提高烟叶碳氮代谢能力和氮素利用效率,提高烟叶碳水化合物含量和降低烟叶硝酸盐积累量,减氮配合喷施丙三醇是降低烟叶硝酸盐积累的有效途径。      

豆腐渣/淀粉复合膜的制备及其性能

采用豆腐渣、淀粉为原料,以NaOH、丙三醇水溶液为溶剂,经加热溶解后制备豆腐渣/淀粉复合膜,并对复合膜的力学性能和溶液粘度进行了测试分析。利用二次通用旋转组合实验设计法,研究了NaOH浓度、豆腐渣/淀粉复配比、丙三醇含量对溶液粘度和复合膜断裂强度的影响。试验结果表明：NaOH的加入和豆腐渣/淀粉复配比是影响复合膜成膜性的重要因素。在NaOH浓度为1.7%,豆腐渣/淀粉复配比为1.135,丙三醇含量为0g时,复合膜的溶液粘度达到6.25kpa?s,断裂强度达到4.21Mpa。丙三醇作为增塑剂的加入,有利于改善复合膜的脆性。     

丙三醇对玉米醇溶蛋白流变性和黏结性的影响

为了探明改性玉米醇溶蛋白的流变性和黏结性及其相互关系,研究了丙三醇、温度、剪切速率等对玉米醇溶蛋白流变性和黏结性的影响。结果表明,丙三醇改性的玉米醇溶蛋白具有假塑性流体特性,呈现"剪切变稀"现象。丙三醇含量、剪切温度和剪切速率对玉米醇溶蛋白的流变性有显著影响。随丙三醇含量的增加,玉米醇溶蛋白的黏度明显增加;随剪切温度的增加,黏度呈先下降后增加的趋势,当温度为308 K时,黏度最低;随剪切速率的增加,黏度呈下降趋势。随丙三醇含量的增加,改性玉米醇溶蛋白对竹颗粒的黏结性呈先增加后下降的趋势,当丙三醇体积分数为10%时,黏结性较佳。改性玉米醇溶蛋白的黏度逐渐增加时,其黏结性呈先增加后减小趋势。     

微生物产丙三醇概述

丙三醇是由油脂皂化、水解和丙烯合成来进行生产的化工产品,由微生物生产是新的研究开发领域。微生物合成丙三醇在产品安全性、生产原料来源等方面具有较大的优势。虽然微生物合成丙三醇产业化潜力仍面临较大竞争压力,但从近来对微生物产丙三醇的研究进展看,随着对丙三醇消费的不断增加和产品成本的降低,发展微生物生产丙三醇前景是广阔的。     

水分活度降低剂在罗非鱼片干燥加工中的应用

采用单因素试验以及四因素三水平L9(34)正交试验,研究了丙二醇、丙三醇、NaCl和乙醇对干燥罗非鱼片水分活度、复水率和色差的影响。结果表明:丙二醇、丙三醇、NaCl和乙醇均能有效降低罗非鱼片的水分活度;用综合加权评分法对干燥罗非鱼片水分活度、复水率和色差值进行分析,影响综合加权评分值的主次顺序为:NaCl>丙三醇>丙二醇>乙醇,最佳组合为丙二醇添加量3%,丙三醇添加量5%,NaCl添加量1%,乙醇添加量3%。     

加热丝材质和雾化温度对电子烟气溶胶主要成分释放量的影响

为探索加热丝材质和雾化温度对电子烟气溶胶主要成分释放量的影响。利用电子烟综合测试平台,以组装了静态初始阻值相同的Ti、Ni200和SS316加热丝电子烟为研究对象,考察在180℃-300℃雾化温度范围内电子烟气溶胶中烟碱、丙二醇、丙三醇的释放量变化。结果表明:1) 三种加热丝动态实时阻值与工作温度呈现较强的正相关;2）同一雾化温度下,静态初始阻值相同的Ti、Ni200和SS316加热丝雾化烟碱、丙二醇和丙三醇的效率,Ni200最大,Ti次之,SS316最小;3）电子烟气溶胶中烟碱、丙二醇和丙三醇释放量均随三种加热丝雾化温度的上升呈现增加趋势,烟碱释放量在220 - 240 ℃之间快速增加,之后增幅不大;4）随着雾化温度升高到260 ℃,丙二醇和丙三醇的相对释放量发生了十分明显的变化,丙三醇的释放量高于丙二醇释放量。      

蒸馏单甘酯的重金属限量试验改进研究

研究取消饱和硫化氢溶液的蒸馏单甘酯重金属限量试验的最佳方法。分别用硫代乙酰胺、硫化钠和硫化钠-丙三醇进行实验并与饱和硫化氢比较,结果表明,硫化钠-丙三醇法简单、快捷,为最佳方法。     

Simultaneous use of transglutaminase and rennet in white-brined cheese production

The effects of renneting temperature (30 °C or 34 °C) on textural properties, proteolysis and yield of white-brined cheese made by simultaneous use of microbial transglutaminase (mTG) and rennet were investigated. Incorporation of mTG resulted in higher yield values for experimental cheeses than for the control cheeses at both renneting temperatures. The total solids contents of the cheeses treated with mTG were remarkably lower than the control cheeses; but the former cheeses had higher protein-in-dry matter levels. The TPA profiles of the cheeses showed that the incorporation of mTG led to modification in the textural properties. The development of proteolysis in the cheeses treated with mTG was slightly slower than the control cheeses at both coagulation temperatures. To conclude, the specific action of mTG on milk proteins could be successfully exploited to modify the textural properties and to increase the yield of white-brined cheese.     

转谷氨酰胺酶改性明胶高强度薄膜的制备

在研究制备转谷氨酰胺酶（mTG）改性明胶可食性薄膜工作的基础上，通过在成型工艺中进一步采用室温干燥和湿态二次定向处理的方法，获得了抗张强度达18．3MPa，韧度达8．4J／cm^2的可食性明胶薄膜。在配料中添加质量分数2％的聚乙烯醇（PVA）并采用相同的成型工艺，所制备明胶薄膜的机械性能得到进一步提高。生物降解性实验表明，在被质量分数0．5％的Alcalase碱性蛋白酶作用4h后，不含PVA的可食性明胶薄膜的降解率可达99．2％，含PVA明胶薄膜的降解率也达到了97．5％。     

Sorption Characteristics of Soy Protein Films and their Relation to Mechanical Properties

Effects of plasticizers (glycerol, sorbitol, and 1:1 mixture of glycerol and sorbitol) on moisture sorption characteristics of hydrophilic soy protein isolate (SPI) films were investigated at three levels of plasticizer concentration (0.3, 0.5, and 0.7 g plasticizer/g SPI). The combined effects of relative humidity and plasticizer on mechanical properties of soy protein films were also examined. Moisture affinities of soy protein films were affected by hydrophilicity of plasticizer and its concentration. Under given RH conditions, films with higher glycerol ratio absorbed more moisture with higher initial adsorption rate, and films with higher plasticizer contents exhibited higher equilibrium moisture contents. Monolayer moisture contents of SPI films increased as glycerol ratio in a plasticizer mixture and plasticizer concentration increased. Plasticizer and absorbed water loosened the film synergistically, resulting in higher elongation but lower tensile strength. RH effects on mechanical properties of SPI films were varied with plasticizers and their concentration. Films of lower glycerol contents were more sensitive to RH variation as compared to the higher glycerol samples, whereas sorbitol concentration affected the RH region where a sharp decrease in TS value occurred.     

Development and characterisation of a new biodegradable edible film made from kefiran,an exopolysaccharide obtained from kefir grains

This study examined the feasibility of using kefiran, an exopolysaccharide obtained from kefir grains, as a new film-forming material. Kefiran-based films, with and without glycerol as plasticizer, were prepared by a casting and solvent-evaporation method. To study the impact of the incorporation of glycerol into the film matrix, physical, mechanical, and thermal properties of the films were investigated. As expected, the increase of glycerol concentration from 15% to 35% w/w increased extensibility but decreased tensile strength, implying higher mobility of polymer chains by the plasticizing effect of glycerol. Water vapour permeability of films was found to increase as the plasticizer content increased. Glass transition temperatures decreased as a result of plasticization as glycerol content increased. The properties of the films were related to their microstructure, which was observed by scanning electron microscopy. Thus, it was observed that plasticizer is a significant factor in the properties of these films and their food technology applications.     

Production and Properties of Spin‐Coated Cassava‐Starch‐Glycerol‐Beeswax Films

Cassava‐starch based polymer films containing glycerol as a plasticizer (1.0‐2.5‐5.0%, w/w) and different lipids as additives (paraffin, stearyl alcohol, and beeswax – 0.25‐0.5‐1.0%, w/w) were produced. Control films were produced by heating a mixture of glycerol, starch, and water, while treated films were produced by the addition of lipids/ ethanol solutions. The solutions were kept at around 70ºC during amalgamation, and once congealed, were placed in a vacuum oven for 1 h at 90ºC. The solutions were then spun on 7‐inch diameter non‐stick disks, allowed to dry, and conditioned at 23ºC and 50% RH before testing. Cassava starch‐glycerol‐beeswax films were successfully produced with a stable film structure at glycerol concentration equal or below 5% (w/w). Addition of glycerol and beeswax did not visually change the color of the films. Increasing glycerol content improved elongation while decreasing tensile strength. Increasing the glycerol concentration from 1.0 to 5.0% increased the water vapor permeability by 150% and addition of beeswax further increased these values by 250%.     

Potato peel-based biopolymer film development using high-pressure homogenization, irradiation, and ultrasound

Edible films were developed from potato peel. High-pressure, gamma-ray, and ultrasound were applied to potato peel solutions to break down biopolymer particles in the solution small enough to allow for biopolymer film formation. Film properties, including moisture barrier and tensile properties, color, and microstructures, were investigated from the films formed with different concentrations of plasticizer (glycerol) and emulsifier (soy lecithin). High-pressure homogenization (HPH) produced the best films among the treatments at the conditions used in this research. Water vapor permeability (WVP) of films decreased by 32% with decrease in the concentrations of glycerol and soy lecithin by 40 and 75%, respectively. As the concentration of glycerol or soy lecithin increased, tensile strength of the films decreased up to 71%, but the elongation at break increased up to 161%, demonstrating lubricant effects of glycerol and soy lecithin. The lightness and yellowness of the films increased and the redness decreased with increase in the concentration of glycerol or soy lecithin. The concentrations of glycerol and soy lecithin were identified as important variables in producing biopolymer films from potato peel.     

Effect of Glycerol on Water Vapor Sorption and Mechanical Properties of Starch/Clay Composite Films

Plasticized starch/clay composite films were prepared by casting aqueous solutions containing oxidized corn starch, different concentrations of glycerol as a plasticizer and 5% clay (sodium montmorillonite, Na⁺‐MMT) on the basis of dry starch. The water‐binding properties of the composite films were evaluated by water vapor sorption isotherms at room temperature and various relative humidities (RHs). Mechanical properties and abrasion resistance were also analyzed for the films with varying glycerol contents at 68% RH and room temperature. Changes in water sorption isotherms suggested that glycerol interacted with both water and starch in a complicated way. A saturation phenomenon of glycerol, depending on RH, was observed based on the isotherms. Above this saturation content, phase separation of the system occurred with the appearance of free glycerol. According to mechanical performance and abrasion resistance, as well as water vapor sorption of the starch blend films, the three‐stage transition was presented to be related to the state of glycerol in the blend system, i.e. adsorption of glycerol onto H‐bonding sites of starch, supersaturation of glycerol as plasticizer and further supersaturation of glycerol. Only above the supersaturation content can glycerol play a plasticizer role in starch‐based composites.     

Effects of plasticizers on thermal properties and heat sealability of sago starch films

Sago starch films were plasticized with sorbitol, glycerol, or a combination of sorbitol/glycerol (1:1, 1:3, and 3:1 ratios) and the effects on the thermal properties and heat sealability of the films were investigated. Films were sealed with an impulse heat sealer at a dwell time of 1 s and temperature of 110 ± 10 °C. Thermal properties of the films (determined using a differential scanning calorimeter) showed that onset temperatures (T_o) of sorbitol-plasticized films were significantly lower than those of glycerol-plasticized films. All films were heat sealable, but sorbitol-plasticized films exhibited better heat sealability than did the glycerol type. The highest seal strength was obtained with a 3:1 combination of sorbitol/glycerol. In summary, the type of plasticizer governed the heat sealability as well as the seal strength of starch films.     

生物甘油基聚酯对大豆分离蛋白复合膜贮藏期间机械性能稳定性的影响

以大豆分离蛋白（soybean protein isolate,SPI）为主要原料,将甘油进行改性后制备的生物甘油基聚酯加 入到成膜液中制备SPI复合膜,通过对贮藏期间SPI复合膜机械性能、水分含量和甘油迁出率进行跟踪测定,比较分 析甘油经改性后制备的增塑剂对SPI复合膜的机械性能稳定性、保水性、甘油迁出率稳定性及微观结构的影响。研 究结果表明：与未改性甘油增塑的SPI复合膜相比,改性后制备的机械性能稳定性最高的SPI复合膜为生物甘油基聚 酯（生物聚甘油和脂肪酸的质量比为1∶1）增塑的复合膜,其拉伸强度稳定性提高了18.08%,断裂延伸率稳定性提高 了34.52%,水蒸气透过系数稳定性提高了14.68%,水分含量稳定性提高了17.02%,甘油迁出率稳定性提高了74.28%, 膜体系的紧密性和连续性增强,且其表面形成了致密的空间网状结构。生物甘油基聚酯的添加一定程度上提高了SPI 复合包装薄膜的机械性能稳定性,为其更广泛的实际应用提供了重要的理论参考和技术支持。     

Mechanical and water vapor barrier properties of extruded and heat-pressed gelatin films

Gelatin-based edible films were produced by extruding hot melt of gelatin-based resins through a die with slot orifice and followed by heat-pressed method. The resins were plasticized with glycerol, sorbitol and the mixture of glycerol and sorbitol (MGS). The effect of type of plasticizer on extruded and heat-pressed (EHP) film-forming capacity was studied, and the mechanical and water barrier properties of resulting EHP gelatin films were compared with those of gelatin films prepared by solution casting method. Stretchable films were formed when glycerol or MGS were used as plasticizer, whereas resins plasticized with sorbitol were extruded in non-stretchable sheets. Glycerol plasticized gelatin film showed the highest flexibility and transparency among the EHP films tested. Tensile strength (TS), elongation (E) and water vapor permeability (WVP) of glycerol plasticized EHP gelatin films were 17.3 MPa, 215.9% and 2.46 ng m/m² s Pa, respectively, and EHP gelatin films had higher E values, lower TS values and higher WVP values compared to the glycerol plasticized cast gelatin films.