转谷氨酰胺酶对大豆蛋白粘度的影响

利用转谷氨酰胺酶(TGase)对大豆蛋白进行改性,并对其粘度进行研究。随着TGase加量的增加,蛋白溶液的粘度不断增加。脱脂豆粉(LTSP)、大豆分离蛋白(SPI)和11S蛋白的粘度均在45℃时最大,而大豆7S蛋白在温度为50℃时粘度最大。随反应时间的延长,体系粘度呈先增加后减少的趋势,大豆11S蛋白的粘度在反应时间为90min时达到最大,其他三种蛋白在120min时粘度最大。     

环氧氯丙烷交联海藻酸钠的制备及性能

用环氧氯丙烷和海藻酸钠反应制得交联海藻酸钠,红外图谱、粘度和热稳定性质的改变证实了交联反应的发生.用正交试验法得到优化合成条件:温度 50 ℃,反应时间 3 5 h,环氧氯丙烷用量为绝干海藻酸钠质量的5 0%,pH值为10.通过交联作用,质量分数1%的海藻酸钠溶液粘度从560 mPa·s上升到 680 mPa·s. 以 1 5 ℃/min从 20 ℃升温到 70 ℃,交联产物粘度下降了95 mPa·s,而海藻酸钠下降了280 mPa·s.     

磁性壳聚糖微球对大豆乳清废水中蛋白质的吸附作用

采用磁性壳聚糖微球吸附的方法吸附大豆乳清废水中蛋白质。实验结果表明,当磁性壳聚糖微球投入量为25g/L,接触时间为10min,温度为30℃,pH值5.0的条件下能有效吸附大豆乳清废水中蛋白质,吸附大豆乳清废水中蛋白质去除率最高达95.6%。     

楠竹溶解浆的制备

本文对楠竹制溶解浆的工艺进行了优化,优化工艺是:在170℃下预水解120min;然后采用硫酸盐法蒸煮,蒸煮条件为:用碱量14%(Na2O计),硫化度20.5%,保温温度165℃,保温时间90min;接着采用ECF漂白,制得了α-纤维素含量为98.74%、聚合度为1062、粘度为18.11mPa*s、白度为88.96%ISO、灰分含量为0.06%、尘埃度为3mm2/500g的高质量溶解浆.     

大豆蛋白质的酶促速凝

测定了6种商品蛋白酶胶凝大豆蛋白质过程中体系粘弹性质的变化曲线,定量比较结果表明,木瓜蛋白酶(papain)和微生物蛋白酶(alcalase)具有较强的使大豆蛋白质胶凝的能力.Papain的热和pH稳定性均优于alcalase,因而更适合于用作速凝凝固剂.当papain的添加量为0.05～0.133g/dL时,速凝形成的大豆蛋白凝胶强度随添加量的增加而增大,进一步增大papain用量会对大豆蛋白质的胶凝产生不利的影响,至添加量为0.2g/dL,速凝1min后出现储能模量(G′)值的急剧下落,最终导致反应后期不能形成凝胶.     

纸浆板用大豆分离蛋白胶黏剂的制备及其性能研究

研究了不同体系下的大豆分离蛋白、苹果多酚和十二烷基磺酸钠加入量对大豆分离蛋白胶黏剂性能的影响。以纸浆板的胶合强度、大豆分离蛋白胶黏剂的黏度和疏水性为指标,通过单因素试验确定大豆分离蛋白胶黏剂的最佳制作工艺:10 g大豆分离蛋白加入100 mL质量浓度为5 g/100mL的聚乙烯醇溶液中,搅拌均匀后加入1.0 g葡萄糖和0.1 g亚硫酸钠,经过90℃、20 min高温处理,冷却至室温,加入0.8 g的苹果多酚静置2 h,调节pH为8.0,添加0.20 g十二烷基磺酸钠与0.1 g海藻酸钠,搅拌均匀,35℃恒温静置1 h。此条件下得到的大豆分离蛋白胶黏剂的疏水性指数2 676.4,黏度1 683 mPa.s,纸浆板的胶合强度0.77 MPa,粘纸浆板效果较好。     

谷氨酰胺转氨酶对大豆蛋白游离伯胺含量的影响

利用了在硫基乙醇作用下,邻苯二甲醛(OPA)试剂与伯胺可以发生荧光反应,使用荧光分光光度计快速检测溶液中游离伯胺含量。应用此方法研究了加酶量、反应温度、反应时间、及反应pH对谷氨酰胺转氨酶(TGase)作用于大豆分离蛋白后对其游离伯胺含量的影响,并对主要影响因素利用响应面发进行优化,找出TGase反应条件的最佳组合。实验结果表明:加酶量20 U/g,反应温度为52℃,反应时间60 min,反应pH 7为TGase最佳反应条件,改性后每克大豆分离蛋白伯胺含量由0.059μmol减少为0.028μmol。     

高度乙酰化大豆磷脂的制备工艺研究

采取萃取的方法制得高纯度大豆浓缩磷脂,再通过乙酰化的方法对其进行改性研究,最佳工艺条件为:正己烷1.5mL/g,乙醇1mL/g,乙酸酐用量3%,温度60～70℃,时间40min,pH7.0,搅拌速度30r/min,得高度乙酰化磷脂,其丙酮不溶物含量56%,水分0.75%,酸价35mg/g,粘度2900mPa.s(25℃),氨基氮含量1.0mg/g。     

酶转化淀粉液用于瓦楞原纸表面施胶的试验

使用高温α-淀粉酶制备了高浓度、低粘度的环保型淀粉液用作瓦楞原纸表面施胶剂.最佳制备工艺条件为:α-淀粉酶用量对绝干淀粉量10U/g,95℃、PH=6下反应20min,所得产品固含量20%,粘度12.2mPa·s.用于瓦楞原纸表面施胶,可使环压指数提高97.9%～155%;对于定量90g/m2以下的低定量瓦楞原纸,也能获得较理想的强度性能.     

转谷氨酰胺酶对淡水鱼糜制品凝胶强度影响

本文研究了转谷氨酰胺酶(TGase)对淡水鱼糜凝胶强度的影响.结果表明,TGase的用量、作用时间和作用温度对鱼糜凝胶强度有明显的影响.在自然pH值下,用10U/g蛋白质的TGase于42℃处理2h.鱼糜的凝胶强度达到最大,比未加酶的凝胶强度增加近1倍.     

谷氨酰胺转胺酶对火腿肠凝胶性质的影响

在火腿肠中添加 6 57U/ g蛋白质的谷氨酰胺转胺酶 ,2 5℃下反应 6 0min ,再于85℃下蒸煮 6 0min ,则火腿肠组织的凝胶破坏力比对照组提高了 6 0N ,凝胶强度比对照组提高了 30 %。在 50mg/mL肌球蛋白溶液中加入 0 0 2U/mg蛋白质的谷氨酰胺转胺酶 ,于37℃、pH 7 0条件下保温 6 0min ,形成可倒置的凝胶。经扫描电子显微镜 (SEM)观察 ,发现此凝胶形成了致密的三维网状结构     

一株西藏灵菇嗜热链球菌产胞外多糖的流变学特性

以一株西藏灵菇嗜热链球菌为研究对象,系统地研究质量浓度、剪切速率、热处理、pH及盐离子对其所产胞外多糖流变学特性的影响。结果表明,该胞外多糖溶液具有良好的增稠性,质量浓度为8.6 mg/mL时其黏度可达到85.63mPa.s;多糖溶液呈高度假塑性,剪切稀释现象明显;热稳定性差,当温度由20℃升至100℃时,其黏度下降了74.4%,分别于60,80℃热处理150min,对多糖溶液黏度有不同程度的影响;多糖溶液黏度在酸性条件下相对稳定,但在中性和碱性条件下明显升高;并且随Ca2+浓度升高,多糖溶液黏度显著下降。     

Purification of transglutaminase and its effects on myosin heavy chain and actin of spent hens

The purpose of this study was to purify pig plasma transglutaminase (TGase) and examine its effects on the myosin heavy chain and actin of the breast muscles from spent hens at different temperatures. TGase (0.3 units/mg) was added to myofibrillar proteins solution (0.5 ml) at 4°C for 0, 4, 8, 12, 24 and 48 h; at 25°C for 0, 1, 2, 4, 8, 12, 24 and 48 h; at 37°C for 0, 5, 10, 30 and 60 min. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that plasma TGase was composed of units of molecular weights approximately 75,000 and 80,000. TGase added to the myofibrillar proteins solution indicated that the concentration of the myosin heavy chain and actin decreased when incubated at 4°C for 48 h and when incubated at 25°C for 2 h. Moreover, the relative intensity determined by scanning densitometry of the SDS-PAGE gel indicated that the myosin heavy chain and actin concentration decreased to 45 and 64%, respectively. In addition, the relative intensity of the myosin heavy chain and actin declined to 7 and 63%, respectively, when incubated at 37°C for 5 min. The relative intensity of both the myosin heavy chain and actin decreased with time when incubated at 25 and 37°C.     

热处理和转谷氨酰胺酶对凝固型酸乳品质的影响

为了揭示热处理和转谷氨酰胺酶(Transglutaminase,TGase)共同作用对凝固型酸乳品质的影响,本研究以不同条件热处理(70℃ 15 min、80℃ 15 min、90℃ 15 min、95℃ 5 min)的牛乳为原料,在发酵的同时添加不同浓度(0、5、10 U)TG酶,制得凝固型酸乳,并对其总体颜色变化值(ΔE)、持水性、硬度、pH和感官评分进行测定。结果表明,热处理温度由70℃升高到95℃会使酸乳(0 U,TGase)的ΔE升高18.86%,持水率升高12.39%,硬度升高7.48%,储存24 h和21 d时的pH分别降低0.19和0.13,并获得更浓郁的乳香。TG酶处理可以改善酸乳的稠度、口感、组织结构等感官特性,明显提高酸乳的持水率,降低色差和减缓后酸化速率,其作用效果随着TG酶浓度的升高而增大。在95℃下热处理5 min,添加10 U TG酶的酸乳拥有更好的品质特性,其色差较相同温度未加入TG酶的酸乳降低8.11%,持水率升高5.56%,储存24 h和21 d时的pH分别降低0.08和0.38,硬度也提升了23.30%。研究表明热处理和TG酶对提高酸乳的品质并改善酸乳的凝胶结构起协同作用,95℃热处理5 min,加入10 U TG酶可能是生产凝固型酸乳的最佳条件。     

Effect of Transglutaminase on Physicochemical Properties of Set-style Yogurt

In this study, the effect of some ingredients such as skimmed milk powder, whey, sodium caseinate, calcium caseinate, whey protein concentrate (35, 60 kg/100 kg dry solids), whole milk powder, condensed milk and transglutaminase (TGase) on the properties of set-style yogurt was investigated. These protein and dry matter sources (2%) and TGase (1 U/g milk protein) were added into pasteurized milk and incubated prior to fermentation for 2 h at 40°C. After fermentation, enzyme action was stopped by heating for 1 min at 80°C. The control groups were conducted with addition of these materials into milk without TGase. All of the milk samples were inoculated with yogurt cultures at 45°C, until the pH was dropped to 4.4. Syneresis, gel-strength, acetaldehyde amounts, and the degree of TGase reaction were determined. As a result, yogurt products made from enzyme-treated milk showed increased gel strength and less syneresis. SDS-PAGE results showed that the enzyme TGase produced crosslink formation between different protein fractions of milk. In addition, it was also determined that TGase application caused a decrease in acetaldehyde amounts.     

Physical Properties of Mixed Dairy Food Proteins

Foods may contain more than one type of protein, and food formulators sometimes combine different proteins for desired synergistic textural benefits. Egg albumin, fish protein isolate, or soy protein isolate were blended with calcium caseinate or whey protein isolate and mixed in water adjusted to pH 2.5, 6.8, and 9.0 at 25 or 60°C. The effect of pH and temperature on solubility, viscosity, and the structure of the resulting gels were determined. The viscosity at the most soluble concentration at 25°C were: egg albumin (175.2 mPa.s/35 wt%), fish protein isolate (2207.4 mPa.s/30 wt%), soy protein isolate (2531.5 mPa.s/10 wt%), calcium caseinate (1115.8 mPa.s/15 wt%), and whey protein isolate (161.2 mPa.s/35%). In mixed protein systems viscosity values were reduced. The values for calcium caseinate or whey protein isolate with egg albumin, at the protein level of 15 g/100 g were: calcium caseinate/egg albumin (10:5 wt%) 535.1 mPa.s and whey protein isolate/egg albumin (10:5 wt%) 8.7 mPa.s. Microscopy imaging revealed changes in protein aggregation clusters during heating of calcium caseinate, egg albumin, and whey protein isolate. Egg albumin acted synergistically to increase viscosity, while fish protein isolate acted antagonistically to reduce viscosity. This knowledge is useful to manufacturers who may seek to enhance food texture by blending different proteins.     

Gelation and Water Binding Properties of Transglutaminase-treated Skim Milk Powder

Transglutaminase (TGase)-treated skim milk powder (TG-SMP) was prepared by freeze-drying skim milk after TGase treatment (10 U/g milk protein, 40°C for 3 h), followed by TGase inactivation at 85°C for 5 min. TGase modification resulted in significant increases in hardness and water holding capacity (WHC) of heat-induced gels (10% protein, w/v). A marked increase in storage modulus (G') of TG-SMP upon heating suggests that TG-SMP has a greater gelling ability than control-SMP (C-SMP) prepared with predenatured TGase. Acid gels prepared from TG-SMP had a significantly higher WHC at all solid levels (12%, 14%, and 16%) tested and formed a more elastic network than C-SMP.     

响应面优化谷氨酰胺转氨酶改性大豆与啤酒糟混合蛋白工艺

为改善啤酒糟蛋白的凝胶性能及氨基酸组成,采用单因素试验及响应面试验研究谷氨酰胺转氨酶改性啤酒糟与大豆蛋白混合的最优工艺条件,探讨啤酒糟蛋白添加量、加酶量、水浴温度、水浴时间和pH值对混合蛋白凝胶性能的影响。结果表明,湿磨法所得啤酒糟蛋白的蛋白质质量分数为52.23%,其氨基酸组成以Glu、Pro为主,而酶改性最佳工艺条件为啤酒糟蛋白添加量30%、加酶量15?U/g、反应pH?7、水浴温度48?℃、水浴时间132?min。在此条件下,混合蛋白的凝胶强度为218.55?g。本研究为啤酒糟蛋白的精深加工提供实验参考。     

谷氨酰胺转氨酶预交联改善CaSO4诱导大豆分离蛋白凝胶性的研究

酶法改性能够有效提升大豆蛋白的凝胶性。为了探讨谷氨酰胺转氨酶(transglutaminase, TGase)预交联对盐诱导大豆分离蛋白凝胶性的影响,通过控制酶浓度、预交联时间制备不同预交联程度的大豆分离蛋白(soy protein isolate,SPI)溶液,并研究其在CaSO₄作用下的成胶性能。结果显示,与未经TGase处理的SPI相比,TGase适度预交联能够显著提升SPI的凝胶品质。经3～5 U/g TGase预交联20 min或3 U/g TGase预交联20～30 min后,SPI凝胶性得到了不同程度的提升,其中弹性模量、屈服应力、屈服应变、持水率最大分别提高了124.5%、269.0%、135.0%及53.0%。然而,过度预交联产生过大的蛋白聚集体,导致最终形成的凝胶结构粗糙、多孔,凝胶强度、持水力等均显著下降(P<0.05)。由此可见,合理利用TGase对蛋白进行预交联处理能够改善SPI凝胶制品品质,对于TGase在食品工业中的应用及传统豆制品质构改良具有重要的指导意义。     

TG酶和漆酶对双歧杆菌益生菌酸奶品质的影响

为了比较谷氨酰胺转氨酶(TG酶)和漆酶的添加对双歧杆菌益生菌酸奶感官、蛋白质交联及组织质构变化的影响,测定和分析了两种酶交联益生菌酸奶的游离氨基变化率、感官、质构、表观黏度、蛋白条带及微观结构,并添加阿魏酸改善漆酶酸奶的品质。结果表明:当TG酶用量增加时,TG酶交联酸奶的游离氨基变化率、感官得分和硬度显著增大(p<0.05),胶黏性、粘聚性及表观黏度先增大后减小(p<0.05),内聚性变化不显著(p>0.05),TG酶最佳用量为1.8 U/g;随着漆酶用量的增加,漆酶酸奶游离氨基变化率、感官得分、硬度、内聚性、胶黏性、粘聚性及表观黏度均先增大后减小(p<0.05),漆酶最佳用量为0.3 U/g;添加4.5 mmol/L的阿魏酸明显改善了漆酶交联酸奶的感官、质构及表观黏度;所有待测酸奶中均缺少β-lg条带,TG酶交联酸奶的κ-CN和β-CN条带消失,聚集成了新的蛋白质,而漆酶交联酸奶和阿魏酸+漆酶酸奶与对照及TG酶酸奶相比,分子量在14 kDa的蛋白条带明显变宽;经两种酶交联的酸奶,三维网络结构变得致密,TG酶交联酸奶的胶粒分布更均匀,网络结构更致密,且在漆酶交联酸奶中添加了阿魏酸后,相较于漆酶交联酸奶,蛋白胶束聚集的更紧密,从而得出,不同类型酶对牛奶乳蛋白质交联的催化作用不同,但均可改善酸奶的感官及食用品质。