酪蛋白磷酸肽防褐变的技术探讨

本文探讨了亚硫酸钠和L-抗坏血酸抑制酪蛋白在水解过程中发生褐变的技术。结果表明，在水解条件下，亚硫酸钠和L-抗坏血酸都能有效的抑制在水解制备酪蛋白磷酸肽过程中发生的褐变反应，减少色素的生成。     

酷蛋白磷酸肽防褐变的技术探讨

本文探讨了亚硫酸钠和L-抗坏血酸抑制酪蛋白在水解过程中发生褐变的技术.结果表明,在水解条件下,亚硫酸纳和L-抗坏血酸都能有效的抑制在水解制备酪蛋白磷酸肽过程中发生的褐变反应,减少色素的生成.     

抑制巴西柳橙汁褐变的研究

开展加热处理和抗坏血酸、柠檬酸、L-半胱氨酸、亚硫酸钠、氯化钙和氯化钠等抗褐变添加剂对抑制巴西柳橙汁褐变作用的研究,通过对比处理前后橙汁吸光度的变化,来考察抗褐变添加剂单一组分和复合组分的褐变抑制效果.单一抗褐变添加剂实验结果表明:最终浓度为0.008‰的亚硫酸钠和0.050%的抗坏血酸对橙汁褐变有明显的抑制作用,且前者护色效果更好;柠檬酸对褐变抑制作用有随着浓度增大而增强的趋势;85℃水浴加热及其他抗褐变剂,包括L-半胱氨酸、氯化钙、氯化钠,对橙汁褐变基本无抑制作用.复合抗褐变添加剂实验结果表明:当亚硫酸钠、柠檬酸、抗坏血酸最终浓度分别为0.008‰、0.100%、0.050%时,对橙汁护色作用最佳.     

石榴多酚氧化酶的某些特性及其抑制剂的研究

针对石榴贮藏过程中易发生果皮褐变的问题,以分光光度计法研究了石榴果皮中多酚氧化酶(PPO)的某些特性,考察了柠檬酸、抗坏血酸、亚硫酸钠和β-环糊精等抗褐变剂对PPO活性的抑制效果。研究结果表明:石榴皮中多酚氧化酶的最适温度为40℃,最适pH是7．0,几种底物中单宁与PPO的亲和力最大,试验的几种抗褐变剂中柠檬酸对PPO活性有明显的抑制效果,其次是抗坏血酸,而亚硫酸钠、β-环糊精的抑制效果不明显。     

柿子醋贮藏期间褐变及其抑制方法

研究柿子醋褐变原因及抑制其褐变方法。利用分光光度计和色差法分析柿子醋在贮藏期间总酚含量、多酚氧化酶(polyphenol oxidase,PPO)和过氧化物酶(peroxidase,POD)活性以及褐变度的变化,并研究几种抑制剂(NaCl、柠檬酸和L-抗坏血酸)对其褐变抑制的影响。结果表明：柿子醋贮藏期间发生的褐变主要是由于PPO和POD催化氧化总酚类物质引起的酶促褐变。不同质量浓度的褐变抑制剂NaCl、柠檬酸和L-抗坏血酸均显著维持醋液中较高的总酚含量,抑制PPO和POD活性,从而降低褐变度,减缓褐变发生,其中以0.24g/100mL NaCl、溶液1.2g/100mL柠檬酸和0.48g/100mL L-抗坏血酸对柿子醋抑制效果较好。     

抑制剂对蓝莓果汁加工过程的酶促褐变研究

为了解决蓝莓果汁在加工中易引发严重的酶促褐变而影响其食用品质和营养价值的问题,研究了蓝莓果汁加工过程中关键加工单元中酶促褐变的情况,就抗坏血酸、柠檬酸、氯化钙及L-半胱氨酸对酶促褐变的抑制作用进行了研究。探讨复合抑制剂在不同贮藏时间、温度下对果汁褐变程度的影响。结果表明,蓝莓果汁中多数褐变发生在打浆过程,因此抑制剂应该在打浆时加入。单一抑制剂在其所选浓度范围内对蓝莓果汁加工过程中酶促褐变的抑制程度顺序为:L-半胱氨酸>氯化钙>抗坏血酸>柠檬酸。最佳的抑制剂组合为抗坏血酸为0.09%,柠檬酸为0.5%,氯化钙为0.1%,L-半胱氨酸为0.1%。复合抑制剂在25℃和37℃条件下可有效抑制果汁的酶促褐变,而4℃条件下的影响并不显著。该研究可为利用抑制剂控制蓝莓果汁褐变提供理论和参考依据。     

L-抗坏血酸自降解过程的非酶褐变反应动态研究

采用动力学方法,研究了L-抗坏血酸自降解过程中的非酶褐变行为。分别考察了反应时间、反应温度及溶液初始p H对L-抗坏血酸自降解过程中无色中间体(294 nm处特征峰)和褐变物质(420 nm处特征峰)的影响。研究了不同p H时,L-抗坏血酸的自降解过程中非酶褐变的反应动力学特征。结果表明:延长反应时间和提高反应温度均会加快L-抗坏血酸非酶褐变过程的降解,溶液的初始p H对L-抗坏血酸的非酶褐变过程也有较大影响,当p H为4.5时较宜生成无色中间体;而当p H为6.8时较适宜生成褐色物质。L-抗坏血酸的非酶褐变自降解过程符合零级反应动力学特征,在各条件下,生成无色中间体的活化能均小于生成褐色物质的活化能。     

菜花贮期防褐变技术研究

菜花是我国的重要蔬菜之一,但其在贮期易发生褐变,降低食用价值,本文通过正交实验研究了菜花防褐变技术.实验结果表明:抗坏血酸、柠檬酸、亚硫酸钠、焦亚硫酸钠具有抑制PPO酶活性和保持CAT活性的作用.防止菜花褐变效果显著,SO2熏蒸和硫酸钠处理对菜花防褐变效果不佳,且贮期菜花质地易变软;采用0.15%抗坏血酸、0.35%柠檬酸、0.5%亚硫酸钠、0.35%焦亚硫酸钠复合水溶液处理菜花,具有良好的防褐变效果.在此条件下.环境温度为1±0.5℃和相对湿度为90%-95%时,贮藏50d,褐变指数仅为0.155.     

正交试验法优化板栗蓉分级护色工艺

为抑制板栗在制蓉过程的褐变,对其加工过程采用二级护色工艺。通过测定样品的总色差(△E*),分别研究了柠檬酸、抗坏血酸、L-半胱氨酸和氯化钠对板栗色泽的影响,进行单因素和正交试验,确定最佳的护色液配方。结果表明,柠檬酸、抗坏血酸、L-半胱氨酸和氯化钠在板栗制蓉过程中均有抑制褐变的效果。一级护色的最佳配方为:柠檬酸0.05%,抗坏血酸0.75%,L-半胱氨酸0.17%,氯化钠2.00%;二级护色的最佳配方为:柠檬酸0.45%,抗坏血酸0.65%,L-半胱氨酸0.05%,氯化钠1.90%。     

罐装绿茶饮料防褐变研究

研究了４种不同化合物对绿茶水高温灭菌过程防褐变的作用。证明四硼钠和亚硫酸钠能够显著抑制高温灭菌对叶绿素的破坏作用,ＵＬ－抗坏血酸和半胱氨酸对高温灭菌过程茶多酚的氧化有显著抑制作用,同时茶汤亮度明显提高。Ｌ－抗坏血酸与半胱氨酸和亚硫酸钠组合处理对绿茶水的保质效果优于Ｌ－抗坏血酸单独处理效果。     

五香大豆防褐变的研究

大豆中含有蛋白质和低聚糖,在一定条件下会发生羰氨反应,即美拉德反应.试验采用单因素和正交试验的方法,根据国家相关标准规范及试验的最终效果,确定五香大豆制品褐变抑制剂柠檬酸、亚硫酸钠、三聚磷酸钠的最佳用量.结果表明:柠檬酸为0.2％,三聚磷酸钠为0.45％,亚硫酸钠为0.01％时,所得的五香大豆制品置于50℃的恒温箱中培...     

The dual effects of Maillard reaction and enzymatic hydrolysis on the antioxidant activity of milk proteins

The objective of this study was to determine the enhanced effects on the biological characteristics and antioxidant activity of milk proteins by the combination of the Maillard reaction and enzymatic hydrolysis. Maillard reaction products were obtained from milk protein preparations, such as whey protein concentrates and sodium caseinate with lactose, by heating at 55°C for 7 d in sodium phosphate buffer (pH 7.4). The Maillard reaction products, along with untreated milk proteins as controls, were hydrolyzed for 0 to 3 h with commercial proteases Alcalase, Neutrase, Protamex, and Flavorzyme (Novozymes, Bagsværd, Denmark). The antioxidant activity of hydrolyzed Maillard reaction products was determined by reaction with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and the ability to reduce ferric ions. Further characteristics were evaluated by the o-phthaldialdehyde method and sodium dodecyl sulfate-PAGE. The degree of hydrolysis gradually increased in a time-dependent manner, with the Alcalase-treated Maillard reaction products being the most highly hydrolyzed. Radical scavenging activities and reducing ability of hydrolyzed Maillard reaction products increased with increasing hydrolysis time. The combined products of enzymatic hydrolysis and Maillard reaction showed significantly greater antioxidant activity than did hydrolysates or Maillard reaction products alone. The hydrolyzed Maillard reaction products generated by Alcalase showed significantly higher antioxidant activity when compared with the other protease products and the antioxidant activity was higher for the whey protein concentrate groups than for the sodium caseinate groups. These findings indicate that Maillard reaction products, coupled with enzymatic hydrolysis, could act as potential antioxidants in the pharmaceutical, food, and dairy industries.     

Maillard reaction contributes to variability in hydration characteristics of rennet caseins in solutions of a calcium-sequestering salt

The objective of this study was to assess the effect of protein modification by Maillard reactions on the functionality of rennet caseins. The extent of Maillard reactions in rennet caseins was determined by measuring furosine levels by a high-performance liquid chromatography method following acid hydrolysis of the casein. An approximately 20-fold range in furosine levels in commercially produced rennet caseins was observed. High furosine levels correlated significantly with increased time taken to reach maximum viscosity index and with decreased maximum viscosity index when the rennet caseins were dispersed in a solution of calcium-sequestering salt, which suggests that modification of casein by Maillard reaction contributes to the variability in the hydration behaviour of the rennet caseins.     

抗美拉德反应在特浓奶香硬糖中的应用

根据国际上对美拉德反应研究的最新成果;;对此反应中的三类中间体的性质、结构进行分析;;从而提出以亚硫酸盐作为美拉德反应的最优阻断剂。经实验表明:以适当的环节、适当的量及适当的反应时间为条件;;亚硫酸盐可以有效地控制美拉德反应在特浓奶香硬糖生产过程中的发生。     

乳制品中美拉德反应机制及控制方法研究进展

乳制品经长时间储存或加热处理后容易发生美拉德反应,导致其营养价值下降,同时也会产生一些羟甲基呋喃,呋喃等对人体有害的物质,因此控制乳制品中美拉德反应对乳制品安全具有重要意义。乳制品中发生美拉德反应的主要成分为乳糖、乳清蛋白及酪蛋白等,且乳糖水解能够进一步促进美拉德反应发生。本文对乳制品中美拉德反应机制、美拉德反应产生的有害物质及控制措施进行了总结,并对乳制品美拉德反应的控制措施进行了重点阐述。本文旨在为乳制品体系中美拉德反应控制提供重要的科学依据。     

The Effects of Antioxidants on Browning and on Degradation Products Caused by Dehydroascorbic Acid

The efficiency of L-cysteine (cysteine) and sodium sulfite as antioxidants was examined in the browning of an aqueous solution of 100 mM dehydroascorbic acid (DHA). The browning was suppressed at 100 mM cysteine and at 40 mM and higher concentrations of sodium sulfite, but it increased in the presence of 10 mM of those agents. These agents did not allow the reduction of DHA to L-ascorbic acid (AA). These results suggest that the suppression or acceleration of browning is likely to be related to some degraded intermediates of DHA. The two colorless intermediates, which during DHA breakdown eventually transform into browning pigments, were discussed with regard to the browning regulation mechanism.     

响应面分析法在米渣水解蛋白-麦芽糊精Maillard反应物乳化特性研究中的应用

通过二次回归通用旋转正交试验设计,应用响应面分析法对米渣水解蛋白-麦芽糊精(RRHP-MD)Maillard反应过程中的各反应条件进行分析,建立数学模型,优化反应条件参数,以求得到乳化活性(EA)佳的RRHP-MDMaillard反应共聚物。结果表明:在58℃,采用水解度(DH)为6的RRHP,保持其与MD的比例为8:1,pH为6.5,反应3d可以得到高乳化活性的反应共聚物。在此最佳反应条件下对反应共聚物的乳化活性进行了研究,证实了预测值和实测值是一致的。此时,反应物乳化活性比国外进口的酪朊酸钠还要好。     

Effects of Galactose Concentration on Characteristics of Angiotensin-I-Converting Enzyme Inhibitory Peptides Derived from Bovine Casein in Maillard Reaction

Bovine casein peptide had a strong angiotensin-I-converting enzyme inhibitory activity. The objective of this study was to evaluate the effects of the galactose concentration on angiotensin-I-converting enzyme inhibitory activity, antioxidant activity, and physicochemical properties of Maillard reaction products derived from bovine casein peptide and galactose in aqueous model system. The browning intensities of galactose-bovine casein peptide Maillard reaction products increased remarkably with the galactose concentration increased during heat treatment, while its pH and amino groups decreased significantly. The fluorescence compounds of galactose-bovine casein peptide Maillard reaction products reached the maximum when the galactose concentration was 45 g/L. Compounds with molecular weight between 2941 and 8864 Da were dominant while compounds smaller than 250 Da were also produced during the reactions, as characterized by size exclusion chromatography. Galactose-bovine casein peptide Maillard reaction products lost 14.6% of the original angiotensin-I-converting enzyme inhibitory activity of bovine casein peptide after the addition of galactose concentration ranged from 0 to 12%, but its strong antioxidant activities were obtained. A high galactose concentration could decrease angiotensin-I-converting enzyme inhibitory activity of bovine casein peptide and enhance its antioxidant activities.     

玉米黄色素稳定性的研究

以玉米为原料,对影响玉米黄色素稳定性的因素进行研究.结果表明:玉米黄色素的最大吸收波长为448 nm,该色素不耐高温,日光照稳定性差;pH对玉米黄色素的稳定性无影响;除金属离子Fe3+、Al3+外,大多数金属离子对玉米黄色素无影响;低浓度糖、高浓度抗坏血酸对玉米黄色素有一定保护作用;而双氧水、苯甲酸钠、山梨酸钾对色素有明显的破坏作用.