Moisture sorption and thermodynamic properties of cassava starch and soy protein concentrate based edible films

Moisture sorption isotherms and thermodynamic properties of cassava starch and soy protein concentrate–based edible films were investigated. Equilibrium moisture content was determined at various temperatures (10, 20, 30 and 40 °C) and relative humidities (17–83%) using gravimetric method, and the results were analysed using four sorption isotherm models. The equilibrium moisture of edible films (both adsorption and desorption modes) decreased with soy protein concentrate addition and temperature at constant water activity. The monolayer moisture content values of cassava starch–soy protein concentrate edible films decreased with increase in temperature and soy protein level. GAB and Oswin models (%RMS ≤10) best described the isotherms of the biofilms with the monolayer moisture contents, isosteric enthalpy and entropy higher for adsorption with significant kinetic compensations. The moisture sorption and thermodynamic properties of cassava starch–soy protein concentrate edible films showed that they are suitable for packaging applications.     

超声辐射对大豆分离蛋白膜性能的影响

研究了超声辐射在频率为20kHz,功率为800W条件下,不同处理时间对大豆分离蛋白膜性能的影响。结果表明,超声辐射对膜性能有明显的改善作用。经超声辐射处理2min可以显著提高膜的抗拉强度,相对于对照样提高了64.08%(P≤0.05);同时也明显降低了膜的水蒸汽透过系数,相对于对照样降低了25.70%(P≤0.05)。经超声处理后的膜机械强度和阻湿性能均得到了提高,同时具有均匀透明的外观。     

Biopolymer interactions affect the functional properties of edible films based on agar, cassava starch and arabinoxylan blends

Edible films based on the binary combination of agar (AG), cassava starch (CAS) and arabinoxylan (AX) were studied with regard to their microstructure, moisture barrier and mechanical properties. Though the films appear macroscopically homogeneous, electron microscopy observations reveal a phase separation and dispersion, respectively, in AG–CAS and AG–AX blend film structures, whereas the structure of CAS–AX blend films seems homogeneous. In case high moisture (84% and 99% RH), neither the combination of AG and CAS nor the addition of AX into CAS can improve film moisture barrier properties, except at a lower RH (57%). Conversely, water vapor permeability (WVP) of AG based film is significantly reduced when AX is used as an “additive”. On the other hand, blending AG with CAS increases the surface wettability of AG films but not that of CAS films. Adding AG into CAS induces an improvement in elongation and tensile strength of CAS based films. Mechanical properties of agar based films are degraded when CAS or AX was added. The results suggest that AG is able to provide a very good cohesive matrix, which contributes to enhance the mechanical properties of other polysaccharide based films.     

热处理和碱处理对可食性大豆分离蛋白膜性能的影响

研究了热处理和碱处理对可食性大豆分离蛋白(SPI)膜性能的影响。对成膜液进行适当的加热和调节pH可以提高SPI膜的抗拉强度(TS)和伸长率(E),降低水蒸气透过系数(WVP)。调节成膜液的pH到9,在70℃加热20min,所得到的膜机械性能和阻湿性能最好。     

Edible films made from membrane processed soy protein concentrates

Edible films were prepared from membrane processed soy protein concentrate (MSC) at various film forming solution pHs, and their mechanical, barrier, and physical properties were compared with soy protein isolate (SPI) films. As the film solution pH increased from 7 to 10, the resulted MSC films were more transparent, yellowish, and had lower oxygen permeabilities. However, tensile strength (TS), modulus of elasticity (ME) and water vapor permeabilities of MSC films were not affected by film solution pHs. The values of MSC films prepared at pH 7 were not significantly (P>0.05) different from those of SPI films prepared at alkaline solutions (pH 8-10). The uniform TS and ME values of MSC film over the wide film solution pH ranges were attributed to the higher solubility of MSC at pH 7. For the films formed at neutral film solutions (pH 7.0), MSC films showed significantly (P<0.05) higher elongation value, film solubility, and transparency compared to SPI films.     

可食性果蔬膜包装材料研究进展

目的:为了研究双酶复合酶解大豆分离蛋白制备大豆肽的相对分子量分布及活性片段对实验性高血压大鼠的降压效果。方法:通过单因素实验优选,采取正交实验优化复合酶的酶解工艺,以酶解液对血管紧张素转换酶(ACE)抑制率为指标优选最佳工艺;通过超滤、纳滤后得到最佳分子量片段,应用左硝基精氨酸(L-NNA)诱导大鼠高血压模型,分别给予不同剂量的活性片段进行实验。结果:双酶复合酶解的最佳条件为:在料液比为1:20 g/mL的情况下,酶解温度50℃,酶底比3.0%,酶解pH7.0条件下先用菠萝蛋白酶酶解2 h后,再以酶底比4.0%加入胰蛋白酶,控制温度为40℃、酶解pH为8.0条件下酶解4 h,大豆分离蛋白的水解度35.31%。经过高效液相对酶解液的相对分子量分布得出,大豆分离蛋白原液含有的蛋白质及多肽的相对分子质量主要区间在5000~1.0×10⁵ Da,在双酶复合酶解下,酶解液的蛋白质及多肽的相对分子质量主要区间均在500~4000 Da;通过超滤得出最佳活性片段为1000~3000 Da,药理实验表明,与模型对照组相比各组血压均有降低,且大豆肽剂量组有显著性差异(p<0.05);其中大豆肽高剂量组和卡托普利组相当。结论:双酶复合酶解制备的大豆肽相对分子量较小,活性片段对高血压大鼠模型降压作用显著。     

玉米淀粉与小麦淀粉复合可食用膜工艺研究

以玉米淀粉和小麦淀粉为成膜基质,采用流延法制备可食用膜,以膜的力学性能作为考查指标,通过单因素实验研究质量比、山梨醇含量、柠檬酸含量、增强剂含量、糊化温度、糊化时间对力学性能的影响,在单因素基础上,以四因素三水平的正交实验优化的最佳制膜工艺条件。结果表明,在淀粉溶液浓度60 g/L,玉米淀粉和小麦淀粉质量比40∶60,山梨醇含量0.6%,柠檬酸含量2.5%,增强剂含量1.4%,糊化温度85℃,糊化时间40 min,干燥4~6 h的最佳制膜工艺条件下,复合膜的拉伸强度为14~15 MPa,断裂伸长率为30%~33%。      

几种多糖和交联剂对可食性大豆分离蛋白膜性能的影响

为了提高可食性大豆分离蛋白膜的性能,研究了多糖和交联剂对可食性膜性能的影响。结果表明,在大豆分离蛋白成膜液中添加0.5%(W/V)的果胶能有效增加膜的机械强度,添加0.1%(W/V)的葡萄糖能有效降低膜对水蒸气、氧气的透性。因此,果胶和葡萄糖对其性能的改善效果较佳,果胶和葡萄糖能改善大豆分离蛋白成膜特性的可能机理是因为它们增加了蛋白分子之间的交联。     

环氧基交联剂对可食性大豆分离蛋白膜性能的影响

为了提高可食性大豆分离蛋白膜的性能,加入环氧基交联剂,考察了环氧基交联剂不同添加量对蛋白膜性能的影响。结果表明,环氧基交联剂的加入,可使大豆分离蛋白膜的机械性能增加显著,蛋白膜机械性能与交联剂的加入量显著关联。3种溶剂(甲苯、四氯化碳、四氢呋喃)溶胀实验表明,在实验条件下交联剂加入量在0.4~0.5 g时,蛋白膜交联程度较为理想。     

醇法大豆浓缩蛋白改性工艺条件的研究

主要对醇法大豆浓缩蛋白改性工艺条件进行了研究,探讨了改性过程中加水温度、溶液pH、超声时间对改性工艺的影响。通过正交实验得出最佳工艺条件为:将醇法大豆浓缩蛋白加100℃水溶解,调pH为10,超声时间30 m in,在此条件下生产的产品水溶性蛋白质可达57.2%,氮溶解指数(NSI)为81.5%。     

Development of starch-based peelable coating for edible packaging

This research characterised properties and stability of starch-based peelable coating film layers via mould dipping. Different ratios between rice starch (RS) and hydroxypropyl cassava starch (HS) containing agar blends were characterised for fluid rheology and properties of solid films. Layer-by-layer mould dipping in starch blend suspensions produced peelable shells. Rheology indicated that formability of thin-film layer on solid surface subsequently affected integrity of the shells. HS highly adsorbed water which plasticised matrices giving lower relaxation temperature (~10 °C) than RS and caused shrivelling and non-stable shell structures. RS increased crystallinity and non-homogeneity of films and reduced network flexibility and light transmission. IR spectra indicated modified hydrophobicity and hydrogen bonding of starch blends which governed water and oxygen permeability. Higher RS ratios significantly increased crystallinity which affected physical, mechanical and barrier properties during storage for three months. Findings indicated that HS provided flexibility and stability while RS improved formability of peeled shells.     

大豆分离蛋白与谷朊粉可食性复合膜研究

该文报道影响大豆分离蛋白与谷朊粉复合膜成膜因素,分析各种因素对复合膜性能影响,并对正交试验结果采用极差分析和综合评分法进行评定,得到制备综合性能良好的可食性膜最佳条件为:谷朊粉与大豆分离蛋白比例为1∶5,甘油量为20%,pH为11,预热处理温度和时间分别为80℃和40min;此时,膜的透光率、拉伸强度、撕裂强度、水分含量和水蒸汽透过率依次为60.5%、38.38MPa、198.02N/mm、13.87%和0.507g·mm/kPa·h·m2。     

不同淀粉与大豆分离蛋白混合涂层对冷却牛肉贮藏品质的影响

研究淀粉（木薯淀粉、红薯淀粉、马铃薯淀粉、玉米淀粉、豌豆淀粉和高直链淀粉）与大豆分离蛋白混合可食性涂层对冷却牛肉贮藏品质的影响。研究在4℃下贮藏5d过程中,各种淀粉与大豆分离蛋白混合涂层对冷却牛肉失重率、颜色、pH、硫代巴比妥酸值和感官评价得分的影响。结果发现豌豆淀粉和玉米淀粉与大豆分离蛋白混合涂层不仅有效降低冷却牛肉中水分损失（分别为9.97%和12.83%,低于聚乙烯膜包装）,而且较好的保持冷却牛肉的感官指标。     

利用生产大豆浓缩蛋白副产物发酵酒精的研究

该文利用大豆糖蜜发酵制备酒精,研究了发酵时间、发酵温度、糖蜜浓度、接种量、pH对发酵酒精的影响,并通过正交试验对糖蜜发酵生产酒精工艺条件进行优化,确定其最佳发酵条件为:糖蜜浓度55g/L,发酵温度32℃,发酵时间72h,接种量9％,pH5.0.在最佳条件下,大豆糖蜜发酵酒精得到的酒精度为7.3％vol.     

微波技术提高醇法大豆浓缩蛋白乳化性的研究

制取低成本、高蛋白含量的大豆浓缩蛋白时,乙醇会产生变性作用,从而降低大豆浓缩蛋白的功能特性,因此本研究采用微波技术对醇法大豆浓缩蛋白进行物理改性。通过对固液比、微波功率、改性时间的单因素实验,针对乳化性进行研究,然后进行正交实验方差分析,最终得出微波技术提高醇法大豆浓缩蛋白乳化性最佳工艺条件：固液比1：9、功率500W、时间3min,可提高乳化能力129.9%,乳化稳定性28.0%。     

明胶/淀粉可食性复合膜研究进展

介绍了明胶、淀粉的结构特点以及作为可食性膜的优缺点,并将明胶、淀粉共混作为复合型可食膜,探讨了增塑剂、增强剂以及相分离等因素对其性质的影响.     

可食性蛋白膜研究进展

传统塑料包装材料引起环境污染问题越来越受到人们关注,其安全性也受到人们质疑,发展新型包装材料,将会是未来方向;蛋白膜以其可生物降解性、可食性、隔油、阻气等性能,正成为国内外研究热点。该文阐述蛋白膜成膜机理、膜的特性及分类,并介绍大豆分离蛋白膜、小麦面筋蛋白膜等可食性蛋白膜国内外研究现状。     

氨作碱性剂对醇法大豆浓缩蛋白改性

以氨作碱性剂,通过均质、物化改性、喷雾干燥等方法对醇法大豆浓缩蛋白(SPC)进行改性,以期获得功能性较好醇法大豆浓缩蛋白。实验表明,醇法大豆浓缩蛋白加入氨水后经均质、物化改性、喷雾干燥等步骤可获得溶解性、凝胶性、乳化性等功能性较佳大豆浓缩蛋白。     

可食性大豆分离蛋白膜制备与性质

为探索新型生物膜材料的制备,以大豆分离蛋白为基本材料,探究大豆分离蛋白(SPI)、增塑剂(甘油)、还原剂(Na_2SO_3)、乙醇等添加量和处理温度、成膜液pH、成膜介质等条件对膜的完整率、厚度、透光率、水溶率、水蒸气透过系数、透油性等性质的影响。当SPI浓度在2%~6%时,随着添加量的增加,成膜变得容易,但是膜的厚度增加、水蒸气透过系数和透油系数变大、色泽变深。甘油添加量在2%以下可以改善膜的柔韧性,同时降低膜的透气性能和透油性。添加5%的乙醇也可以降低膜的透气性和透油性。添加0.1%的Na_2SO_3可以改善膜的色泽,同时降低膜的透油性。适当提高处理温度和溶液pH可以降低膜的透气性和透油性。     

Development and characterization of novel probiotic-residing pullulan/starch edible films

An innovative approach was performed to prepare novel pullulan/starch blended edible films by direct incorporation of multiple probiotic bacterial strains. Various starches different in origin were blended into the pullulan solutions with different ratios. The physical and mechanical properties of the films were investigated in the presence and absence of probiotic cells. An increase in the starch content of pullulan films resulted in a substantial decrease in relative cell viabilities and mechanical properties. Moreover, slight changes in the physical and mechanical properties of the films were observed with the addition of probiotic strains. Pullulan and pullulan/potato starch films were found to be the most suitable carrier matrices, with a maximum relative cell viability of 70–80% after 2 months of storage at 4 °C. The results suggest that pullulan and pullulan/starch films can be used as effective delivery and carrier systems for probiotics.