Effect of ascorbic acid on the foaming and gelling of globular proteins

Foam expansion and foam stability of plasma and egg albumen proteins were enhanced in the presence of increasing concentrations of ascorbic acid (0.1–1.0%). BSA showed the greatest improvement in foaming properties following treatment with ascorbic acid, whilst foaming properties of egg albumen were improved to a limited extent. A combination of partial acid hydrolysis and treatment with 1% ascorbic acid was required to dramatically improve the foaming properties of bovine blood plasma. In the presence of sucrose, foam expansion of both native and ascorbic acid-treated blood plasma was decreased. In contrast the foam expansion of ascorbic acid-treated egg albumen was greater although this effect decreased slightly on incubation. the gelation of ascorbic acid treated proteins increased with increasing temperatures over 80–90°C, particularly for BSA and blood plasma, and with increasing concentrations of ascorbic acid. Ascorbic acid-treated proteins exhibited enhanced surface and exposed hydrophobicity and reduced numbers of sulphydryl groups indicating the involvement of these factors in foam and gel formation.     

不同种类糖对燕麦蛋白糖基化产物功能性质及结构的影响

为提高燕麦蛋白(OP)的功能性质,提高其品质,分别采用葡萄糖(G)、乳糖(L)、壳寡糖(C)、海藻酸钠(S)对燕麦蛋白进行湿法糖基化改性,探究4种不同分子大小的糖对燕麦蛋白糖基化产物(G-OP、L-OP、C-OP、S-OP)功能性质及结构的影响。结果表明：4种糖基化燕麦蛋白的溶解性较改性前均有较大提高,其中L-OP的溶解度(pH 7)较改性前提高了64.23百分点;4种糖基化燕麦蛋白的乳化活性指数(EAI)和乳化稳定性指数(ESI)均显著提高(p<0.05),其中C-OP的EAI和ESI较改性前分别增加了8.91 m²/g和21.26百分点;4种糖基化燕麦蛋白的持水性、吸油性、体外消化性及表面疏水性较改性前均显著提高(p<0.05);SDS-PAGE、傅里叶红外光谱、荧光光谱分析表明,糖链的引入使OP空间结构发生了变化,证明了OP分别与4种糖发生共价结合生成糖蛋白。综上,虽然蛋白的糖基化反应是一种化学改性,但由于没有任何化学试剂参与,通过自发反应发生共价交联,生成具有良好功能性质的蛋白糖基化共价复合物,属于“绿色加工工艺”,适合高品质改性植物蛋白的研制...     

燕麦粉添加量对马铃薯—燕麦复合面团特性的影响

目的:研究添加燕麦粉对马铃薯—燕麦复合面团特性的影响,确定适宜的燕麦粉和马铃薯配比。方法:选取了5种不同比例的燕麦粉(15%,20%,25%,30%,35%),对燕麦—马铃薯复合面团的色差、微观结构、质构特性、流变特性、糊化特性进行测定,并进行感官评价。结果:随着燕麦粉添加量的增加,复合面团的颜色逐渐变红变暗;复合面团内部微观结构越来越紧密;硬度逐渐增加;动态频率扫描过程中不同添加量复合面团弹性模量、黏性模量先上升、后下降、再上升,损耗因子先上升后下降。复合面团的起始糊化温度、峰值糊化温度、终止糊化温度先减小再增大。感官评定显示：燕麦粉添加量在20%～25%范围内,总体得分均比对其他添加量的复合面团要高,更易被消费者接受。结论:制备马铃薯—燕麦复合面团时,燕麦粉适宜添加量为20%～25%。     

Effects of cross-linking and acetylation on oat starch properties

Starch samples separated from oat were modified with two different levels of POCl₃ (0.5 and 1.0 g kg⁻¹) as a cross-linking agent and two different levels of acetic anhydride (6% and 8% (w/w)) for acetylation. Swelling factor, thermal properties and retrogradation measurements were evaluated to characterise the influence of phosphorylation and acetylation on oat starch. Cross-linking decreased the swelling factor and did not improve gelatinization temperature while it increased synaeresis in comparison with native starch. Acetylation increased swelling factor but reduced gelatinization temperature and synaeresis of oat starch.     

湿热和韧化处理对莜麦淀粉结构及消化特性的影响

目的 为研究湿热和韧化改性对莜麦淀粉理化性质和消化特性的影响,扩大莜麦淀粉在慢消化主食食品中的应用,方法 分别在体系水分含量为15%、20%、25%、30%,温度为100℃的条件下和料液比为1:5,体系温度为30℃、40℃、50℃、60℃下对莜麦淀粉进行湿热和韧化处理,并采用傅里叶红外光谱（FT-IR）、X-射线衍射（XRD）、扫描电镜（SEM）、差示扫描量热仪（DSC）和酶解实验等分析湿热和韧化处理前后莜麦淀粉的理化性质和消化特性变化。结果 结果表明,湿热和韧化处理均未改变莜麦淀粉原有的A-型结晶结构,但淀粉结晶度表现为下降趋势,且淀粉的糊化焓从1.49J/g分别降低至0.92J/g和0.8J/g。此外,微观结构表明莜麦淀粉颗粒表面结构出现聚集行为。在体外酶解实验中,经过湿热、韧化处理后的莜麦淀粉中慢消化淀粉（SDS）和抗性淀粉（RS）含量均出现不同程度的增加,表现为湿热处理后RS含量增加显著,而韧化处理则显著提高了SDS的含量。结论 结果表明湿热和韧化处理可以通过改变淀粉结构降低莜麦淀粉的消化速率。     

Effect of thermochemical treatment on the structure of inulin and its gelling properties

The aim of this study was to investigate rheological properties of inulin gels and the changes in the inulin structure after heating the high polymerised inulin (DP ≥ 23) solutions at different pH. The 20% inulin solutions were heated at pH 3, 5 and 7 at 60 and 80 °C followed by 21 h storage at 5 and 25 °C. Rheological properties evaluation indicated that the increase in the heating time and temperature significantly (P ≤ 0.05) influenced on the inulin structure. Reducing sugars, cryoscopy and HPLC analysis revealed that chemical structure of inulin is stable in neutral and slightly acidic conditions (pH 5). Gelation of the high polymerised inulin solution after heating at pH 7 and 80 °C could be inhibited after dissolving the inulin crystallites which act like seeding crystals. At lower temperatures in which, not all crystallites were dissolved; it was feasible for the solutions to form firm inulin gels.     

糖基化交联反应对酪蛋白胶凝和乳化性质的影响

利用转谷氨酰胺酶催化酪蛋白与壳寡糖发生糖基化交联反应,控制反应时间(1、2 h和4 h)制备3种糖基化交联蛋白质(修饰酪蛋白),分析糖基化交联反应对酪蛋白胶凝和乳化性质的影响。结果表明:修饰酪蛋白的凝胶时间显著缩短(约50%);凝胶的持水能力为99%(800 r/min条件下离心10 min),较高;凝胶的微观结构发生了显著的变化,而且随着反应时间的延长,凝胶的空间网络结构更加规则;糖基化交联反应对酪蛋白的乳化活性及乳化稳定性影响较大。     

Effects of oat lipids on groat meal pasting properties

The Australian oat cultivar Yarran is unacceptable for human food use due to poor flavour, colour and texture. It has a high lipid content which contains a high proportion of oleic acid. It was compared with an acceptable variety, Mortlock, which has a characteristically lower lipid content with a lower proportion of oleic acid, to study the effect of lipid content on pasting properties of the oat meal. The lipids of both varieties were extracted with petroleum ether and were added back into the defatted meals in sequential amounts. These meals were then tested for viscosity parameters. Both lipid content and composition significantly influenced the meal pasting properties. The peak viscosity and time to peak viscosity were negatively correlated with lipid content whereas setback and pasting temperature increased with increased lipid content. The lipids from Yarran and Mortlock had different effects on the pasting properties. The Mortlock lipid increased the final viscosity (FV) of the defatted meal of Yarran but showed little effect on the FV of its own cultivar. However, the results indicated that the lipid content/composition, although affecting pasting characteristics substantially, were not as important as other meal properties in controlling acceptability for human food use. © 1999 Society of Chemical Industry     

工艺条件对草鱼鱼糜凝胶性质影响的研究

研究鱼糜加工中的漂洗及热凝胶条件对草鱼鱼糜凝胶性质的影响,结果表明,较低浓度的CaC l2溶液(≤0.6%)漂洗鱼糜明显增加了凝胶的强度和弹性,漂洗液中添加NaHCO3使鱼糜吸水溶胀,造成鱼糜脱水困难并降低了凝胶的强度。40℃预凝胶处理对鱼糜凝胶的强度和弹性都有积极的影响,凝胶的强度和弹性都随预凝胶时间而增加,这种增强效应在Ca2+存在时更加显著。     

淀粉对高温杀菌鱼糜凝胶特性的影响

为提高杀菌鱼糜制品的品质,本文研究了添加不同浓度的木薯原淀粉和四种变性淀粉(羟丙基化二淀粉磷酸酯,乙酰化二淀粉己二酸酯,磷酸交联淀粉,羟丙基化淀粉)对120℃高温杀菌鱼糜凝胶特性的影响。通过测定分别添加5%,10%和20%淀粉后复合鱼糜凝胶的破断力,破断距离,凝胶强度,白度,持水率,曲折实验和扫描电镜等指标,研究不同淀粉对杀菌鱼糜凝胶质构性,色泽和持水能力的影响。结果表明各种淀粉适宜的添加量均为10%。在各种淀粉添加剂中,木薯羟丙基化二淀粉磷酸酯和木薯乙酰化二淀粉己二酸酯对高温杀菌后鱼糜凝胶的破断力,凹陷距离的改善效果最好,能显著增强鱼糜的凝胶强度(p<0.05)。添加淀粉均会改善鱼糜凝胶的白度,使白度增加。添加木薯原淀粉,木薯乙酰化二淀粉己二酸酯和木薯羟丙基化二淀粉磷酸酯可不同程度提高鱼糜的持水力。      

Improving gelling properties of myofibrillar proteins incorporating with cellulose micro/nanofibres

The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.     

酶解时间对葵花11S球蛋白结构和功能性质的影响

以脱脂后的葵花籽粕为原料制备了葵花11S球蛋白,并利用碱性蛋白酶Alcalase酶解(控制酶解时间30、60、90、120 min)制备4种酶解产物,探讨酶解时间对酶解产物蛋白质结构和功能性质的影响。凝胶色谱分析结果表明,酶解产物的相对分子质量显著下降;圆二色谱分析结果表明,酶解产物的无规则卷曲结构增加;功能性质分析结果表明,酶解产物在p H 2~9范围内可溶性氮含量达80%以上,短时间酶解产物的起泡性和乳化性提高,但长时间酶解导致产物的泡沫稳定性和乳化性下降。     

碱与热处理对大米蛋白质结构与功能性质的影响

以大米蛋白质为原料,研究碱处理和热处理对大米蛋白质结构与功能性质的影响。研究结果发现:经不同pH处理40 min后,大米蛋白质功能性质均有一定程度改善,其中经pH 12. 0/40 min处理的大米蛋白质溶解性、乳化性与乳化稳定性、起泡性分别提高了2. 46,2. 85,1. 12,2. 51倍;同时, 100 kDa的组分含量减少,此时蛋白质分子中的α-螺旋、β-转角含量分别减少了26. 99%,10. 54%,而β-折叠、无规卷曲含量分别增加了14. 65%,20. 23%。采用50~90℃/40 min的条件对大米蛋白质进行热处理,其结构性质和溶解性、表面疏水性皆无明显变化;但乳化性与乳化稳定性、起泡性则随着热处理温度升高而提高,90℃热处理可达到最大值,分别是原大米蛋白质的2. 41,1. 09,1. 62倍。结果表明经单独碱处理、热处理后,大米蛋白质的结构发生了改变,但溶解度改善效果不明显。     

Effects of succinylation and deamidation on functional properties of oat protein isolate

The effects of two different modification methods (deamidation and succinylation) on the functional properties (solubility, water- and oil-binding capacity, foaming capacity and stability, emulsion activity and stability) of oat protein isolates were evaluated. Protein isolates extracted from defatted oat flour at alkaline pH were acylated by 0.20 g/g of succinic anhydride. The protein isolate was also modified using a mild acidic treatment (HCl, 0.5 N). Succinylation and deamidation improved solubility and emulsifying activity of the native protein isolate. Foaming capacity of oat protein isolate increased after deamidation, whereas succinylation decreased it. The deamidated and succinylated proteins had lower foam and emulsion stabilities than had their native counterpart. Water- and oil-binding capacity, in both modified oat proteins, was higher than those of the native oat protein isolate.     

酪蛋白-卡拉胶体系凝胶特性的研究

以酪蛋白－卡拉胶作为研究对象,研究了ｐＨ、ＮａＣｌ浓度以及Ｐｒ．／Ｃａｒｒ．对体系凝胶特性的影响。结果表明,凝胶强度受各条件变化的影响很大;持水性与凝胶强度、粘度成正比关系;在不添加ＮａＣｌ时,融点、凝固点与凝胶强度成正比关系,但添加ＮａＣｌ时,则与ＮａＣｌ浓度成正比关系;凝胶体具有热可逆性     

纳豆芽孢杆菌蛋白酶对大豆分离蛋白凝胶性的影响

利用纳豆芽孢杆菌发酵所产微生物蛋白酶对大豆分离蛋白进行酶法改性,以提高其凝胶性,并通过测定凝胶体系的流变学性质、水解程度和分析电泳图谱来探究纳豆芽孢杆菌蛋白酶对大豆分离蛋白凝胶性的影响.结果表明,体系凝胶强度受酶浓度和酶解温度的影响,酶浓度为1.072U/mL在40℃条件下形成的凝胶最稳定;同时凝胶强度与水解度有关,50℃时水解度超过12％,则不能形成稳定的凝胶.经微生物蛋白酶作用后,大豆分离蛋白的7s和11s均发生不同程度的水解.     

纳豆芽孢杆菌蛋白酶对大豆分离蛋白凝胶性的影响

利用纳豆芽孢杆菌发酵所产微生物蛋白酶对大豆分离蛋白进行酶法改性,以提高其凝胶性,并通过测定凝胶体系的流变学性质、水解程度和分析电泳图谱来探究纳豆芽孢杆菌蛋白酶对大豆分离蛋白凝胶性的影响。结果表明,体系凝胶强度受酶浓度和酶解温度的影响,酶浓度为1.072U/mL在40℃条件下形成的凝胶最稳定;同时凝胶强度与水解度有关,50℃时水解度超过12%,则不能形成稳定的凝胶。经微生物蛋白酶作用后,大豆分离蛋白的7s和11s均发生不同程度的水解。