没食子酸和芦丁对鱼皮明胶凝胶的溶胀性及水的状态的影响

研究没食子酸和芦丁对鱼皮凝胶的溶胀性及水的状态的影响。结果表明,没食子酸和芦丁均可使凝胶的平衡溶胀率降低,以芦丁的影响较显著。在凝胶溶胀初期,未交联凝胶和没食子酸添加量20mg/g凝胶以及芦丁添加量为6和8mg/g凝胶均表现非Fick扩散过程,而30mg/g没食子酸交联的凝胶表现Fick扩散过程。同时发现,无论是未交联凝胶还是多酚交联凝胶,在溶胀过程中均是凝胶高分子链的松弛过程为速控步骤。通过差示扫描量热法(DSC)对多酚交联凝胶中水的状态分析发现,没食子酸和芦丁对凝胶的平衡水分含量没有明显影响,但可改变凝胶中可冻结水和非冻结结合水的分布。20和30mg/g的没食子酸使凝胶中非冻结结合水含量降低,而6和8mg/g的芦丁却使凝胶中非冻结结合水含量升高。     

热稳定冰结构蛋白对小麦淀粉凝胶冻融稳定性的影响

研究燕麦粉和女贞叶中热稳定冰结构蛋白(TSISP)对淀粉凝胶冻融稳定性的影响。应用差示扫描量热仪(DSC)、扫描电子显微镜(SEM)和质构仪分别研究燕麦粉、女贞叶TSISP对淀粉凝胶冻融后析水率、可冻结水含量、超微结构、硬度及弹性的影响。结果表明:冻融过程显著地增加淀粉凝胶析水率、可冻结水含量,严重地破坏淀粉凝胶超微结构、增加孔洞尺寸、减小孔洞均匀性,最后导致淀粉凝胶硬度明显增大,弹性明显减小;而燕麦粉和女贞叶中TSISP的添加显著地减小淀粉凝胶冻融后析水率和可冻结水含量,同时显著地改善淀粉凝胶超微结构,使得淀粉凝胶孔洞增大幅度明显得到抑制,孔洞均匀性更好,结果也对淀粉凝胶质构产生明显的改善效果,延缓硬度的增加和弹性的减小,使得冻融后淀粉凝胶的总体品质得以提高。     

酰化对大豆分离蛋白凝胶性质的影响

为研究化学改性对大豆分离蛋白（SPI）凝胶性质的影响，采用乙酸酐和琥珀酸酐对SPI进行化学改性，研究酰化程度、pH、盐效应等对其质构特性的影响。结果显示：SPI凝胶体的硬度在pH为6．0时最大，随着氯化钠或氯化钙浓度的增加，凝胶硬度先上升后下降。因此乙酰化和琥珀酰化都可阻止SPI形成热致凝胶，离子强度对大豆蛋白凝胶的质构曲线有很大影响。     

热分析技术在芳纶纤维中的应用研究

介绍了差热分析（DTA）,差示扫描量热法（DSC）,热重法（TG）和动态热机械分析（DMTA）等热分析技术在芳纶纤维热性质分析方面的应用进展。指出芳纶纤维在热压时形态和结构会发生变化,通过对芳纶纤维热性能的研究,可以调整纤维加工条件,改善纤维性能。     

大豆分离蛋白制备过程中热处理及干燥方式对其热聚集行为和凝胶性能的影响

该研究以低温脱脂豆粕为原料,采用“碱溶酸沉”法收集大豆蛋白沉淀,对其进行分散、热处理和喷雾干燥或冷冻干燥制备获得大豆分离蛋白（SPI）。通过观察该产品的热聚集行为及其所成热致凝胶机械性能,考察热处理和干燥方式对所得产品凝胶性能的影响。结果表明,热处理使制得大豆分离蛋白多以聚集体的形式存在,导致其溶解性（pH值7.0）分别从79.9%和69.8%下降至35.2%和42.0%。相对于经过热处理制得的大豆分离蛋白,未经过热处理制得的大豆分离蛋白其差示扫描量热仪分析图存在78 ℃和98 ℃吸热峰;其分散液再次经历热处理后,分散液中蛋白的体积分数约从30%下降至20%,展现出进一步聚集并形成有序结构的趋势;对于质量分数为16%的喷雾干燥大豆分离蛋白（SD-SPI）和冷冻干燥大豆分离蛋白（FD-SPI）样品分散液所制备的凝胶,其断裂应力分别为10.80 kPa和12.50 kPa,显著高于对应HSD-SPI（经热处理）凝胶的3.69 kPa和HFD-SPI（经热处理）的4.36 kPa,但后两者硬度高于前两者。另一方面,干燥方式没有对所得大豆分离蛋白的凝胶性质产生显著的影响。可见,大豆分离蛋白制备过程中对大豆蛋白分散液进行升温热处理是影响所得蛋白产品溶解性、聚集行为和凝胶性能的关键步骤。寻找相应的替代工艺有望提高大豆分离蛋白的品质和功能特性,拓展其在食品工业尤其是植物基食品中的应用。     

差示扫描量热法和热重法评估植物油氧化稳定性的研究进展

对植物油氧化机理及影响因素做简要概述,综述差示扫描量热法(DSC)和热重法(TG)在评价植物油氧化稳定性中的应用,同时介绍了植物油氧化过程中的物性变化,为植物油的质量控制和货架期评估提供参考。     

染苑精萃

混纺织物中纤维含量测定 99062 对涤棉、涤/人造丝混纺织物采用热分析法如热重分析/差示热分析法（TG/DTA）和差示扫描量效法（DSC）来测定混纺织物中各组分的含量。实践表明,这些方法均能有效、快速地测定混纺织物中各     

金属离子对豆腐凝胶模型水分状态的影响

采用大豆分离蛋白模拟传统豆腐的凝胶形成过程,研究了几种金属离子对豆腐凝胶模型水分状态的影响。结果表明:随着Na+、Mg2+浓度的增加,石膏凝固豆腐凝胶模型的溶涨率和平衡水含量均降低,而随着Ca2+浓度的增加,豆腐凝胶模型的溶涨率和平衡水含量升高。随着金属离子的加入,石膏凝固豆腐凝胶模型的可冻水含量下降。在非冻结水方面,随着Ca2+浓度的增大,Wnf值越来越大。但是Na+和Mg2+对凝胶中非冻结水含量影响情况相反。另外,金属离子的加入会缩短凝胶形成时间,说明金属离子促进豆腐凝胶的形成。这为进一步研究传统豆腐凝胶形成的机理和开发新型豆制品提供了理论依据。     

新型香料3,3,6,6-四苄基-1,2,4,5-四硫环己烷的合成及热分析研究

以中间体二苄基二硫醇和三氯化铁为原料，乙醇和水为溶剂，合成了新型香料3，3，6，6-四苄基．1’2’4，5-四磺环己烷，产率为50.3％，用差示扫描量热法（DSC）和热重法（TG）研究其热性质，加热温度为50℃至500℃，加热速率10℃／min.结果表明，在312℃开始分解，应在312℃以下保存，适用于汤料调味品而不适用于烧烤类调味。     

冷冻温度对全荞麦挤压面条品质特性的影响

研究不同冷冻温度对全荞麦挤压面条品质特性的影响，测定了冷冻面条的复热特性，质构特性和水分分布状态；并利用电子扫描显微镜(SEM)观察其微观结构，差示扫描量热仪(DSC)测定可冻结水含量，低场核磁共振(LF-NMR)分析水分分布状态。研究发现，-40℃冷冻处理后的全荞麦挤压面条具有最低的复热损失(5.09%)及吸水率(126.51%),最高的硬度(2 567.83 g)及弹性(0.98)。SEM结果表明-40℃冷冻使面条形成的冰晶较小，内部孔洞结构更为均匀。DSC结果表明，-40℃冷冻处理后，可冻结水含量最低为35.30%。LF-NMR表明-40℃冷冻处理的全荞麦挤压面条结合水含量最高，自由水含量最低，且弱结合水自由度最小，有利于减小冰晶对淀粉凝胶网络结构的损伤。因此，选择合适的冷冻温度(-40℃)可以减少冰晶对挤压荞麦面条内部结构的损伤，从而赋予面条较好的品质特性。     

Thermal stability and transition temperatures of monovalent salts of high‐acyl gellan gels

Thermogravimetry/derivative thermogravimetry (TG/DTG), rheometry and differential scanning calorimetry (DSC) were used to study the thermal stability and determine the transition temperatures of the sodium and potassium salts of high‐acyl gellan (HAG) in the presence of 0–100 mm NaCl and KCl, respectively. TG/DTG revealed the potassium gellan (KHAG) gels to be more stable than those of sodium gellan (NaHAG), regardless of external cation concentration. Rheometry and DSC showed the melting (T_m) and gelling (T_g) temperatures to increase with cation concentration. The DSC peak temperatures showed thermal hysteresis contrary to rheometry. In most cases, DSC revealed KHAG to exhibit higher T_m and T_g than NaHAG. Consequently, thermal characteristics of NaHAG and KHAG gels depend on the size of the external cation and its ability to coordinate water molecules. Cation salts of HAG exhibit significantly lower transition temperatures than the commercial preparation from which they were produced.     

鸡肉蛋白和大豆蛋白的相互作用和机理研究

目的:研究鸡肉蛋白和大豆蛋白在转谷氨酰胺酶催化下的相互作用以及经酶改性后的蛋白质对其凝胶性和乳化性的影响,为开发新型鸡肉产品奠定理论基础.方法:应用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、差示热量扫描(DSC)、荧光光谱等方法研究蛋白质-蛋白质相互作用的机理.结果:酶催化鸡肉蛋白和大豆蛋白发生共价交联反应,生成超大蛋白分子,形成具有三维网络的稳定结构,明显改善了MPI/SPI混合蛋白的凝胶性和乳化性,使混合蛋白的凝胶持水性提高约95％,乳化活性提高约13 m2/g.结论:酶催化鸡肉蛋白和大豆蛋白的共价交联,改善了混合蛋白的凝胶性和乳化性,对大豆蛋白在鸡肉制品中的应用以及改善产品品质提供理论依据.     

Hydration of heat-treated soy protein isolate and its effect on the molten flow properties at an elevated temperature

The relationship between the flow properties of soy protein isolate (SPI) at 140°C, measured using an extrusion viscometer, and changes in the hydration state were investigated. The state of the water in SPI was analysed by measurement of the freezable water content using differential scanning calorimetry (DSC) and by spin-spin relaxation rate (R₂) measurements using pulsed nuclear magnetic resonance (NMR). The dependence of the flow properties on the state of water was indicated by the correspondence between the water content at which the flow characteristics of molten SPI changed, and the critical water content indicated by DSC measurement of the minimum freezable water content, and by the inflection point in NMR measurement of the spin-spin relaxation rate (R₂).     

Development of colloidal carbon-based immunochromatographic strip for rapid detection of carbaryl in fruit juices

The differences in lipid content will lead to differences in protein structure and gel properties and it is a nice model system, so our study, based on the production process for Zhongxiang tofu, used soy protein isolate (SPI) as raw material and adopted circular dichroism and Raman spectrum to investigate the influence of different lipid content on protein secondary structure in tofu. Texture profile analysis and differential scanning calorimetry were used to analyze the influence of lipid on gel texture properties and state of water. The interactive mechanism at microscopic level was investigated by means of scanning electron microscopy. The results show that the additional lipid reacted with the soy protein and the lipid became a component of a newly formed molecular membrane. With an increase in added lipid, SPI gel hardness was reduced, while springiness increased. The proportion of α-helix and β-sheet in SPI gel at 16% (w/v) lipid are 4.0 and 26.0%, respectively. The equilibrium water content tended to decrease when lipid content was increased.     

基于人体必需金属盐替代的低钠盐肌原纤维蛋白凝胶特性和作用机理

为降低肌原纤维蛋白凝胶中钠盐的使用量,研究不同氯盐(CaCl₂、MgCl₂、KCl)部分替代NaCl对肌原纤维蛋白凝胶性质包括强度、微观结构、持水力和流变学性质的影响,并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、内源性荧光光谱、表面疏水性、巯基含量等技术手段阐明其作用机理。结果表明,3种氯盐替代效果排序为KCl>CaCl₂>MgCl₂。0.5%～1.5%质量分数的盐替代范围内,KCl替代组的凝胶强度优于对照组(3%NaCl),持水力与对照组相比无显著差异(P>0.05);Ca Cl₂替代组的凝胶强度在1.5%替代质量分数时显著下降(P<0.05),持水力呈先下降后上升趋势;MgCl₂替代组凝胶强度显著降低(P<0.05),持水力上升。在流变学性质方面,不同质量分数KCl替代组的储能模量明显高于对照组。CaCl₂和MgCl₂的替代使肌原纤维蛋白表面疏水性增大、巯基含量减少,3种氯盐的替代...     

不同物理法提取高温大豆粕中蛋白的比较研究

比较了加热、均质、超声和微波4种物理手段对提取高温大豆粕中大豆蛋白的辅助作用,并对不同方法提取的蛋白进行了聚丙烯酰胺凝胶电泳(SDS-PAGE)、粒度分布、相对分子质量分布及热性质分析.研究发现120 ℃(0.1 MPa,20 min)热处理对大豆蛋白的提取效果最好,蛋白浸出率可达65.58%.SDS-PAGE、凝胶渗透色谱(GPC)和粒度分布结果显示,加热、超声和微波处理所得蛋白提取物为高相对分子质量聚集体,但除微波处理外,其分子粒径也有所减小;均质可使蛋白提取物的相对分子质量、粒径减小.差示量热扫描(DSC)结果表明,均质处理所得提取物尚有吸热峰存在,而其他手段处理所得提取物已完全变性.     

Gelation Property of Alcohol-Extracted Soy Protein Isolate and Effects of Various Reagents on the Firmness of Heat-Induced Gels

Gelation property, thermal property, protein subunits distribution, and molecular forces involved in gelation of alcohol-extracted soy protein isolate were investigated using texture analyzer, differential scanning calorimeter, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and various reagents. Results showed that salts and pH played important roles in gel firmness, and a power law relationship between gel firmness and protein concentration was observed. The effects of various reagents revealed that disulfide bonds play a major role in soy protein gel formation, while the involvement of electrostatic interactions, hydrogen bonds, and/or hydrophobic interactions also occurred in gel networks. Thermal analysis indicated that both alcohol-extracted soy protein isolate and commercial soy protein isolate (isoelectric precipitation) have undergone serious denaturation, while the gel firmness of alcohol-extracted soy protein isolate was significantly greater than that of commercial soy protein isolate. Sodium dodecyl sulfate polyacrylamide gel electrophoresis image showed that there was almost no difference for protein subunits among alcohol-extracted soy protein isolate, commercial soy protein isolate, and soy powder. Hence, as an alternative environmental friendly extraction method, alcohol-extraction of soy protein isolate has a great prospect to replace presently applied isoelectric precipitation method.     

无机盐对酶促大豆蛋白胶凝特性的影响

为了探究无机盐对大豆蛋白酶促胶凝过程热动力学特性及凝胶强度的影响规律,以大豆分离蛋白分散液(Dispersion of soybean protein isolate,DSPI,4%,m/m)为材料,以木瓜蛋白酶为凝固剂进行酶促胶凝试验,测定不同无机盐种类及浓度下的胶凝时间,并通过Arrhenius方程求出反应活化能;以凝胶强度为指标,利用Box-Behnken中心组合设计试验建立以Ca2+浓度、温度及酶添加量为参数的凝胶强度模型。结果表明添加无机盐(Na Cl、KCl、Ca Cl2、Mg Cl2和Mg SO4)可降低酶促DSPI凝胶的活化能,但Arrhenius曲线仍呈线性关系,说明无机盐可加快反应速度,但胶凝反应仍遵循同一机理;显著性检验及响应面分析表明所建凝胶强度模型拟合度较高,木瓜蛋白酶添加量对凝胶强度影响显著(P0.05),Ca Cl2添加量与温度的交互作用对凝胶强度的影响极显著(P0.01),Ca Cl2和温度同时较高或较低时,均不利于提高凝胶强度。     

Effect of Partial Substitutes of NaCl on the Cold-Set Gelation of Grass Carp Myofibrillar Protein Mediated by Microbial Transglutaminase

The objectives of this study were to investigate the changes and the relationship between structure and physiochemical properties of low sodium salt substitutes (NaCl partially replaced by KCl, CaCl₂, and MgCl₂) on grass carp myofibrillar protein gels mediated by microbial transglutaminase during cold-set gels and to provide more information about the gel characteristics. The gel strength, water holding capacity, whiteness, rheological characteristics, differential scanning calorimeter (DSC), and Raman spectra of cold-set gels were determined. The Raman spectra data were fitted to four secondary structures (α-helix, β-sheet, β-turn, and random coil). The gel properties of cold-set gels varied both with the low sodium salt types and incubation time. Myofibrillar protein (MP) gels added with NaCl and KCl had significantly higher water holding capacity than the MgCl₂, CaCl₂, and control groups. Additionally, the results showed that the gel strength and G’ value increased with the incubating time. No significant difference was detected in whiteness between the NaCl group and partial substituted groups. Cold-set gels added with the same molar amount of NaCl and KCl had fairly similar gel properties. There is a strong correlation between structural properties and gel properties of MP gels determined by DSC during the cold-set gelation process.     

Formation of Soy Protein Isolate Cold-set Gels: Protein and Salt Effects

ABSTRACT: The influence of protein and calcium concentration on soy protein cold-set gel formation and rheology has been investigated. Cold-set gels can be formed at soy protein concentrations from 6% to 9% and calcium concentrations from 10 to 20 mM. Gel properties can be modulated by changing the protein and/or CaCl₂ concentrations. An increase in CaCl₂ concentration from 10 to 20 mM increased gel opacity while an increase in protein concentration from 6% to 9% decreased opacity. Water-holding capacity improved with increasing protein concentration and decreasing CaCl₂ concentration. The elastic modulus (G') increased with protein and calcium chloride concentrations. Microscopy revealed an increase in the diameters of aggregates and pores as CaCl₂ concentration increased and as protein concentration decreased. Cold-set gels with a broad range of characteristics can be obtained from soy protein.