冷冻干燥过程中热传递对淀粉海绵孔洞结构的影响

淀粉具有良好的生物相容性和生物可降解性,因此淀粉海绵在伤口敷料、止血剂等领域有广阔的应用前景.采用冷冻干燥法制备多孔淀粉海绵,糊化淀粉乳液中的水在不同的冷冻条件下结晶会对孔洞结构造成不同影响,研究了冷冻速度和传热方向对孔洞尺寸和取向的影响,发现预冻温度决定海绵孔洞尺寸,随着预冻温度的降低,孔洞尺寸也随之减小,并且孔洞尺寸、取向以及均一性都受到冷冻过程中传热条件的影响.     

丝素/明胶三维多孔支架的构建及其结构和性能表征

应用冷冻干燥技术,在不同预冻温度下制备不同质量比例的三维多孔支架,用扫描电镜观察支架的微观形貌,X射线衍射仪分析其表面相结构,并测定了其吸水率、孔隙率和热稳定,观察不同质量比例和预冻温度对丝素(silkfibroin,SF)/明胶(gelatin,G)三维多孔支架结构和性能的影响。结果显示,通过改变材料的质量比例和预冻温度可以控制支架的孔隙形貌、吸水率和孔隙率,并且将丝素与明胶复合可以使支架的热稳定性提高,同时结构更加稳定。     

机械活化木薯淀粉接枝丙烯酸制备高吸水性树脂的研究

采用搅拌球磨机对木薯淀粉进行机械活化,以机械活化木薯淀粉和丙烯酸单体为原料,以过硫酸铵-亚硫酸钠为引发剂,通过水溶液聚合法制得淀粉基高吸水性树脂.考察了淀粉机械活化时间、淀粉与单体配比、反应温度、反应时间、和引发剂用量等因素对产品吸水率的影响,得出产品在室温下1h内吸蒸馏水3100g/g、自来水459g/g、0.9%NaCl盐水272 g/g.     

影响壳聚糖-胶原蛋白冻干海绵敷料结构、性能的因素

壳聚糖-胶原复合敷料具有良好的生物相容性、抗菌性和促进表皮细胞生长等特性,可作为深二度烧伤敷料。通过冷冻干燥法制得的海绵敷料的外观、内部结构、吸水率、舒适性等性能取决于制备条件,其中预冻步骤最为关键。本工作探讨了-70℃、-40℃、-20℃的三种预冻条件对冻干产品外观和内部结构的影响,同时考察不同物料浓度(2.0~3.5%)和不同壳聚糖/胶原蛋白比例(2/1、1/1、1/2)时海绵敷料性能,实验表明,-40℃预冻30min,物料浓度2.5%,壳聚糖/胶原蛋白比例2/1,所制得的海绵敷料外观工整,内部孔结构均匀,且具有良好的结构稳定性、吸水性和舒适性。红外光谱分析表明,壳聚糖-胶原蛋白冻干海绵由于氢键交联作用,使冻干产品不同于原材料壳聚糖或胶原蛋白,冻干产品具有更牢固的组织结构。     

纳米SiO2改性生物降解复合薄膜研究

目的以壳聚糖(chitosan)、木薯淀粉和聚乙烯醇(PVA)为基础成膜原料,探究纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的制备工艺过程。方法以薄膜断裂伸长率、抗张强度、透光率和吸水率为评判标准,在单因子试验基础上,设计L9(34)正交试验,研究纳米SiO2含量、分散剂十二烷基苯磺酸含量、膜液pH值等3个因素对纳米SiO2改性木薯淀粉/聚乙烯醇/壳聚糖薄膜性能的影响。结果得出了制备纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的最佳工艺参数,纳米SiO2质量分数为2.0%、十二烷基苯磺酸钠质量分数为2.0%、膜液pH值为3.0,3个因素对改性薄膜性能的影响程度大小排序为分散剂含量纳米SiO2含量pH值。结论获得了纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的最佳生产工艺参数。     

马铃薯淀粉疏水化改性研究

目的通过正交实验找到淀粉疏水化改性的最佳实验方案和工艺条件。方法利用氧化法、交联法和酯化法对马铃薯淀粉进行疏水化改性;利用正交设计助手(Ⅱ)3.1筛选出制备改性淀粉的最佳实验条件组合,得到吸水率和黏度性能的最优方案为交联法;用SPSS13.0进一步对交联法实验数据进行单因素分析和方差分析。结果交联改性将马铃薯淀粉的吸水率降低了43.44%,在液体石蜡中的黏度降低了70.54%;综合考虑吸水率和黏度等2个指标及实际可操作性,得到最佳工艺条件:水浴温度为55℃,p H值为11,环氧氯丙烷和淀粉干基的质量比为1.5∶100,此时得到的疏水化改性淀粉吸水率为20.96%,黏度为156 m Pa·s。结论制备疏水化改性淀粉的最佳方法为交联法,并得到了最佳工艺条件,为提高淀粉疏水化性能的研究提供了依据。     

木薯渣纤维制备发泡缓冲包装材料的研究

以木薯渣为原料,加入可溶性淀粉、交联剂、催化剂和发泡剂后烘焙发泡,制备了新型植物纤维发泡缓冲材料。分析了木薯渣粒度和胶粘剂、发泡剂、催化剂用量等对发泡缓冲材料静态缓冲特性的影响;通过Statis-tics Analysis System 9.0软件对实验进行了中心组合设计。结果显示最佳发泡条件为:胶粘剂、发泡剂、催化剂添加量分别为2.0,6.0,2.4g;发泡温度为63～68℃,发泡时间为14～17h。     

干法酯化淀粉/聚乳酸复合材料——混合比例对性能的影响

采用干法马来酸酐酯化玉米淀粉和聚乳酸(PLA)进行熔融共混制备可降解复合材料。采用X射线衍射、热重分析和扫描电镜对复合材料的结晶结构、热分解特征和断面形貌进行了表征,从而研究酯化淀粉/PLA混合比例对相容性的影响。并对复合材料的力学性能、吸水率以及流变性能进行了测试。实验结果表明,随着酯化淀粉/PLA比例减小,复合材料中两相的相互依赖性增大,拉伸强度和弯曲强度增大,断裂伸长率和吸水率降低。流变性能测试结果表明,随着酯化淀粉比例增多,复合材料的储能模量增大,复数黏度降低。     

新型双交联羧甲基木薯淀粉的合成与表征

以木薯淀粉为主要原料,经环氧氯丙烷交联,采用一氯乙酸进行羧甲基化,制得交联羧甲基木薯淀粉(CC-MS)。然后采用双交联工艺,经乙二醛二次交联制得黏度高达16000mPa.s的双交联羧甲基木薯淀粉(DCCMS)。通过优化条件实验,考察了乙二醛与交联羧甲基淀粉反应过程中诸因素对黏度的影响。确定了较佳的合成工艺条件:交联温度35℃,交联时间60min,m(NaOH)∶m(CCMS)=0.08∶1,m(乙二醛)∶m(CCMS)=0.28∶1,V(乙醇)∶V(水)=11∶1。产物通过红外光谱、X-射线衍射和扫描电镜进行了表征。     

包装用木薯黄糊精粘合剂的研制

以木薯淀粉为原料,不同的酸为催化剂,采用焙烘工艺制备木薯淀粉黄糊精,研究了不同种类的酸及酸的添加量、反应温度、反应时间对黄糊精粘度及溶解度的影响,确定了黄糊精工业生产的最佳工艺,并以木薯淀粉黄糊精为主原料,高岭土为填料,成功研制了高强快干环保包装粘合剂。     

Effect of physicochemical properties on freezing suitability of Lotus (Nelumbo nucifera) root

The initial physicochemical properties of different lotus roots were studied with the aim to evaluate their influence on freezing suitability. Six physicochemical properties indicators (starch content, whiteness index, maximum diameter, protein amount, titratable acidity and vitamin C) of lotus root were determined by principal component analysis. It was observed from the experimental results that the initial physicochemical properties of lotus root can directly affect the freezing suitability in terms of initial freezing temperature, transition phase time, total freezing time, relative firmness and drip loss. Correlation analysis suggested that relative firmness increases in proportion to starch content, and initial freezing temperature and drip loss are inversely proportional to the starch content. Compared to immersion freezing, power ultrasound can significantly improve the freezing rate and relative firmness but decrease drip loss. These results suggested that high quality frozen lotus root can be achieved via appropriately selecting high starch content lotus root and using ultrasound-assisted immersion freezing.     

聚丙烯酸钠/壳聚糖互穿聚合物海绵的制备及应用探索

以聚丙烯酸钠和壳聚糖为原料,以戊二醛为交联荆,在醋酸溶液中合成了聚丙烯酸钠/壳聚糖互穿聚合物,并采用冷冻诱导相分离法制备了具有多孔结构的海绵,用红外光谱(FT-IR)和扫描电镜(SEM)对其结构进行了表征,并研究了影响海绵溶胀性能的多种因素.实验结果表明,当m CTS∶mPAANa=1:1.11、mCTS:m戊二醛=1...     

Simulation of coupled heat and mass transfer during freezing of a porous humid matrix

A numerical simulation using Lees's three-level scheme and a fixed grid was carried out to predict heat and mass transfer during the freezing of a porous humid matrix. The simulations predict local moisture content, temperature and weight loss of the foods throughout the freezing process. The model accommodates the effects of temperature dependent variables such as apparent specific heat, enthalpy, thermal conductivity, and water activity. The model was validated by experiments on a cellulose sponge. The results of the model showed good agreement with experimental data.     

聚乙烯醇/壳聚糖互穿聚合物海绵的制备及应用探索

以聚乙烯醇和壳聚糖为原料,戊二醛为交联剂,透明质酸钠和明胶为添加剂,在醋酸溶液中合成了聚乙烯醇-壳聚糖互穿聚合物,并采用冷冻诱导相分离的方法制备了具有多孔结构的海绵,用红外光谱(FT-IR)和扫描电镜(SEM)方法对其结构进行了表征,研究了影响海绵溶胀性能的多种因素。实验结果表明,当mPVA-1788∶mCTS=6∶1、mHANa∶mCTS=0.4∶1、m戊二醛∶mCTS=0.283∶1、mGEL∶mCTS=1∶1、CPVA-1788=0.97 mol/L时,可制得吸水倍率约为25 g/g成型性能较好的多孔高吸水性海绵。用此海绵对兔耳创面的出血进行止血实验测试,结果表明海绵的止血率为100%,且止血时间缩短、总失血量减小,达到了快速有效的止血效果。     

预处理及解冻方法对马铃薯冻融品质的影响

目的 提高马铃薯冻融后的品质,为PEF预处理在蔬菜冷冻领域的应用提供理论依据。方法 探讨预处理方法(脉冲电场、热处理)和解冻方法(常温解冻、水里解冻、冰箱解冻)对马铃薯冷冻–解冻过程及品质的影响,分析冰晶成核温度、融化温度、汁液损失比、色泽、硬度等理化指标,并通过低场核磁共振仪分析冻融后样品不同状态下水分间的迁移情况。结果 热烫和高压脉冲电场(Pulsed Electric Field,简称 PEF)预处理均可显著降低冷冻时间、提高冰晶成核温度。PEF预处理样品在最大冰晶体形成带的滞留时间相较于对照组样品降低了26.3%。在不同解冻方式下,PEF预处理和热烫预处理均可降低马铃薯冻融后的汁液损失。在常温下解冻,对照组、热烫组、PEF预处理组的汁液损失率分别为24.12%、17.39%、15.53%。PEF预处理和热烫预处理可减缓食品在冻融过程中的颜色和硬度的变化进程。结论 PEF预处理可以改善冻融后马铃薯的品质,可为PEF在果蔬冷冻领域的应用提供理论参考。     

基于响应面-主成分分析法优化豆渣膨化食品的配方

目的为了克服新鲜豆渣难以膨化的缺点,添加小麦面粉、玉米淀粉和水进行复配,开发出一款膨化效果较好、品质较高的豆渣膨化食品。方法将湿豆渣、小麦面粉、玉米淀粉和水按一定比例混合均匀,利用单螺杆挤压膨化机对其膨化,然后添加防腐酒,最后进行真空包装。单因素实验以500 g湿豆渣为基准量,选取小麦面粉的质量分数、玉米淀粉的质量分数和水的质量分数作为影响因素,并以膨化度、弹性、硬度、胶黏性和咀嚼度作为评价指标,再通过响应面-主成分分析法确定最佳配方。最后测定产品菌落总数和感官分数以确定防腐酒的质量分数和产品保质期。结果在小麦面粉质量分数为83%,玉米淀粉质量分数为20%,水质量分数为31%时,产品的膨化度为5.61,弹性为0.97,硬度为1178.43 g,胶黏性为935.33,咀嚼性为1028.05。添加质量分数为1%的防腐酒后并真空包装,产品在常温下的保质期至少可达6个月。结论湿豆渣与小麦面粉、玉米淀粉和水按最优配方复配后,产品膨化效果较好,品质优良。     

超疏水石墨烯/甲醛-三聚氰胺-亚硫酸氢钠共聚物海绵的制备及其在油水分离中的应用

采用两步法合成了石墨烯（GE）改性的超疏水超亲油甲醛-三聚氰胺-亚硫酸氢钠（FMS）共聚物海绵,首先在FMS海绵基质上进行GE原位聚合,然后通过聚甲基苯基硅氧烷构筑超疏水结构。采用FTIR、SEM、TGA、光学接触角测量仪对海绵结构进行表征分析。结果表明,GE成功地修饰了FMS海绵,制备出的GE/FMS共聚物海绵的接触角达158.9°。将GE/FMS共聚物海绵用于油水分离,经20次对机油吸附-解吸附测定后仍能保持稳定的超疏水性质。改性后的GE/FMS海绵具有良好的可重复利用性且对油和有机溶剂具有高度选择吸收性,对氯仿和机油的吸收量分别达到自身质量的约125倍和90倍,对油或有机溶剂的回收率达到87%以上。进一步对油或有机溶剂与水的分离进行了应用模拟,结果表明:改性后的GE/FMS海绵可以高效快速地将油或有机溶剂从水中分离出来,对于投入生产及吸附应用具有实际意义。      

淀粉冻融特性及其品质影响因素研究现状

目的 针对反复冻融对淀粉质食品组织具有破坏作用,融化后产品水分会损失且质地易软化,造成品质下降、消费属性降低等现象,总结和研究该现象的机制和相关影响因素。方法 对淀粉在冻融过程中的老化回生、硬度上升、析水率提高等品质劣变问题,以及影响冻融稳定性的重要因素进行探讨。结果 淀粉来源,直链与支链淀粉含量,盐、糖的加入等均会对淀粉冻融稳定性造成影响,但具体效果受环境因素影响程度较大,有待进一步探究。结论 阐述了影响淀粉基食品冻融稳定性的重要因素,探究其可能的作用过程和机理,为含淀粉质食品的品质改良途径提供理论依据。     

An unusual superhydrophilic/superoleophobic sponge for oil--water separation

Development of porous materials with anti-fouling and remote control- lability is highly desired for oil–water separation application yet still challenging. Herein, to address this challenge, a sponge with unusual superhydrophilicity/superoleophobicity and magnetic property was fabricated through a dip-coating process. To exploit its superhydrophilic/superoleophobic property, the obtained sponge was used as a reusable water sorbent scaffold to collect water from bulk oils without absorbing any oil. Owing to its magnetic property, the sponge was manipulated remotely by a magnet without touching it directly during the whole water collection process, which could potentially lower the cost of the water collection process. Apart from acting as a water-absorbing material, the sponge can also be used as affiliation material to separate water from oil–water mixture and oil in water emulsion selectively, when fixed into a cone funnel. This research provides a key addition to the field of oil–water separation materials.     

Freeze–thaw stability of emulsions with soy protein isolate through interfacial engineering

In this paper, we examined to the influence of interfacial composition on freeze–thaw stability of oil in water emulsions. An electrostatic layer-by-layer deposition method was used to create the multilayered interfacial membranes with different compositions of primary emulsion (Soy protein Isolate); secondary emulsion (Soy protein Isolate – octenyl-succinate starch); tertiary emulsion (Soy protein Isolate – octenyl-succinate starch – Chitosan). The primary, secondary and tertiary emulsions were subjected to from one to two freeze–thaw cycles (−20 °C for 24 h, +25 °C for 18 h) and then their stability was assessed by ζ-potential, particle size, microstructure and creaming stability measurements. The crystallization behaviour of emulsions was studied by differential scanning calorimetry (DSC). Primary and secondary emulsions were unstable to droplet flocculation when the water phase crystallized, whereas tertiary emulsions were stable, which was attributed to the relatively thick biopolymer layer surrounding the oil droplets. These results showed the interfacial engineering technology used in the study could therefore lead to the creation of food emulsions with improved stability to freezing and thawing.