合成类蛋白的研究进展

类蛋白反应不仅能有效去除蛋白水解物的苦味,而且能改善蛋白质的营养成分,并且在改善蛋白质的功能特性方面也起到一定效果。本文综述了合成类蛋白反应的反应机制、影响因素以及应用前景。     

合成类蛋白的研究进展

类蛋白反应不仅能有效去除蛋白水解物的苦味,而且能改善蛋白质的营养成分,并且在改善蛋白质的功能特性方面也起到一定效果。本文综述了合成类蛋白反应的反应机制、影响因素以及应用前景。      

罗非鱼下脚料蛋白合成类蛋白反应的研究

以罗非鱼下脚料为原料,采用Alcalase蛋白酶对其进行控制酶解,制备水解度为40%的罗非鱼下脚料酶解蛋白,然后添加胃蛋白酶,对其进行合成类蛋白反应的研究。结果表明:以类蛋白反应产物风味和合成类蛋白产率为指标,响应面分析法优化合成类蛋白反应的最佳工艺条件为:底物浓度31.76%,加酶量2.92%,pH 4.95,温度37℃,反应时间24 h;在此条件下,类蛋白产物风味综合评分为2.56±0.03,类蛋白产率为(8.96±0.11)%,与模型预测值(2.548,.99%)无显著差异,产物风味得到明显改善(p<0.05);SDS-尿素-PAGE和HPLC分析显示,合成类蛋白反应是体系分子量增大的过程,小分子的多肽和氨基酸发生缩合反应,生成了分子量较大的类蛋白。     

合成类蛋白反应与食物蛋白品质改良

合成类蛋白反应在控制食物蛋白营养性和功能性方面显示出巨大的潜力,已成为食品工业的研究热点。综述了其目前存在的各种不同反应机制、反应的影响因素以及其在食物蛋白加工领域的应用研究。     

蛋白质酶法修饰的初步探讨──大豆蛋白和芝麻蛋白的合成类蛋白质研究

本文报道了以大豆蛋白和芝麻蛋白的胰蛋白酶水解物为原料，以胃蛋白酶为催化剂，通过合成类蛋白反应制取合成类蛋白质。结果表明，在上述反应中，胃蛋白酶是一种适宜的催化剂。底物水解度为８０％时效果最佳。大部分底物的分子量在１０００以下。底物最佳浓度为３０％，最佳ｐＨ为５．０。合成类蛋白质分子量约为１０，０００。     

罗非鱼下脚料蛋白合成类蛋白反应的工艺优化

以罗非鱼下脚料为原料,采用Alcalase蛋白酶对其进行控制酶解,制备不同水解度的罗非鱼下脚料酶解蛋白,在此基础上添加胃蛋白酶对其进行合成类蛋白反应的研究。以类蛋白产率为指标,在反应温度恒定(37℃)的条件下,通过单因素实验,确定底物水解度为40%、反应时间24h,选取底物浓度、加酶量和pH值3个因素进行响应面实验,通过响应面分析法优化合成类蛋白反应的最佳工艺组合为:底物浓度44.16%,加酶量4.12%,pH值5.08;在此条件下,类蛋白产率达到(10.08±0.03)%,与响应面二次模型预测值(10.11%)无显著差异。     

乳清蛋白水解物的研究进展及应用

随着经济的发展,人们对营养需求越来越高,更加注重追求更高品质的蛋白质。乳清蛋白经水解后所得到的乳清蛋白水解物,因其易吸收、蛋白品质高,且含有许多生物活性肽而被广泛研究利用,成为近年研究热点。因此,本文系统的论述了乳清蛋白水解物的制备方法、生物活性及在食品中的应用,并对其今后的发展进行了展望,以利于乳清蛋白水解物的进一步开发与利用。     

类蛋白反应在食品中的应用

类蛋白反应通常认为是酶水解的逆反应。通过此反应可合成高分子量的类似蛋白质的物质，从而可以提高蛋白质的生物效价、改善蛋白质水解物的风味和蛋白质的功能性质，并能以该反应来提供新的蛋白质资源。许多研究人员已经将该反应应用于大豆蛋白，牛乳蛋白，鱼类蛋白等食品蛋白中，取得了蓖好的效果。由于类蛋白反应的反应机制仍然不清楚，其研究和应用受到了限制。但随着酶技术和微生物技术的快速发展，类蛋白必将在食品工业领域中得到更广泛和深入的应用。     

蛋白-多糖共价复合物及其应用研究进展

蛋白质和多糖是食品中两类重要的生物大分子,是影响食品质构的主要因素,蛋白质具有乳化且稳定的能力,多糖主要是增稠和持水能力,但是做为添加剂使用时,在某些性能方面无法满足实际需要.蛋白质和多糖在控制条件下通过Maillard反应可发生一定程度的共价复合,而蛋白-多糖的共价复合物显示出比各自独立存在时更优越的性能.因此,蛋白质和多糖共价复合物成为近年来国内外食品科学界研究的一个焦点.本文综述了近年来国内外关于蛋白-多糖共价复合物的研究工作,简要介绍了蛋白-多糖共价复合物的制备方法、反应机理和组成结构,探讨了蛋白-多糖共价复合物的溶解性、乳化性、乳化稳定性、热稳定性、抗氧化性和抗菌性等功能性质,概括了蛋白-多糖共价复合物在众多领域的应用研究进展.     

酶解利用骨蛋白的研究进展

介绍了骨蛋白营养价值、酶解利用骨蛋白的研究动态及主要研究内容，并分析了骨蛋白水解物的应用前景。     

An approach to improve ACE-inhibitory activity of casein hydrolysates with plastein reaction catalyzed by Alcalase

The preparation method of casein hydrolysates with high ACE-inhibitory activity was studied by Alcalase-catalyzed hydrolysis coupled with plastein reaction. Casein hydrolysates with an IC₅₀ value of about 47 μg mL⁻¹ were first prepared by hydrolysis of casein with Alcalase and then modified with plastein reaction catalyzed by the same enzyme. The impacts of four reaction conditions on plastein reaction of casein hydrolysates were studied, and then optimal conditions were determined using response surface methodology with the decrease of free amino groups in the reaction mixture as response. When the concentration of casein hydrolysates was fixed at 35% by weight, the maximum decrease of free amino groups in the reaction mixture of 181.8 μmol g⁻¹ proteins was obtained. The optimum conditions for the above decrease were found to be an E/S ratio of 7.7 kU g⁻¹ proteins, reaction temperature of 42.7 °C and reaction time of 6 h. Analysis results showed that ACE-inhibitory activity of casein hydrolysates prepared could be improved significantly by plastein reaction. When casein hydrolysates were modified by plastein reaction, with a decrease of free amino groups in the mixture of about 154.7 μmol g⁻¹ proteins and 181.8 μmol g⁻¹ proteins, their IC₅₀ values could be decreased to 0.6 and 0.5 μg mL⁻¹.     

类蛋白反应在食品中的应用

类蛋白反应通常认为是酶水解的逆反应。通过此反应可合成高分子量的类似蛋白质的物质,从而可以提高蛋白质的生物效价、改善蛋白质水解物的风味和蛋白质的功能性质,并能以该反应来提供新的蛋白质资源。许多研究人员已经将该反应应用于大豆蛋白,牛乳蛋白,鱼类蛋白等食品蛋白中,取得了良好的效果。由于类蛋白反应的反应机制仍然不清楚,其研究和应用受到了限制。但随着酶技术和微生物技术的快速发展,类蛋白必将在食品工业领域中得到更广泛和深入的应用。     

Application of the plastein reaction to mycoprotein: I. Plastein synthesis

The plastein reaction has been applied for the first time to mycoprotein following in situ digestion of crude material to solubilise protein and produce the required initial peptide mixture. Pepsin was found to be superior to the other proteinases tested (trypsin, chymotrypsin, papain, Streptomyces griseus proteinase) in the plastein synthesis step although in all cases yields of insoluble plastein were low (10–15%). Unusually, plastein yield was not much influenced by pH over the range 3.0–7.5, but percentage yield increased almost linearly over the peptide concentration range 11–43% (w/w) while the absolute yield of plastein increased exponentially over this range. Incubation at different temperatures showed that the rate of plastein formation was highest at 65°C, reaching a maximum in 4–5 h but, although not reaching maximum yield for 24 h, a temperature of 37°C gave approximately 25% greater yield. In general terms, the results suggested that mycoprotein peptides represented a rather poor substrate for plastein synthesis and only opaque, viscous solutions were obtained rather than the more common thixotropic gel structures.     

Application of the plastein reaction to mycoprotein: II. Plastein properties

Mycoprotein peptide hydrolysates have been used as starting materials for plastein synthesis. Compared to other proteins studied, mycoprotein hydrolysates were a relatively poor substrate for the plastein reaction and generally led only to thixotropic viscous solutions, rather than to gelled products, and only low yields of insoluble plastein material. Once formed, however, the insoluble fraction remained insoluble over the whole pH range of 2–11. In contrast to many other plasteins, the mycoprotein material was not solubilised by detergents such as sodium dodecyl sulphate although, like others, it was largely solubilised by 50% (v/v) organic acids or 1 M NaOH and partially solubilised by chaotropic agents such as 8 M urea, 6 M guanidinium chloride and 7 M potassium thiocyanate. A combination of 8 M urea and 50% (w/v) citric acid completely solubilised the plastein to a clear solution. Gel filtration failed to reveal any change in peptide molecular weight distribution on plastein formation while ion-exchange chromotography showed some quantitative differences but these were difficult to interpret as most of the material did not adhere to the anion-exchange column under the conditions used. Amino acid analysis revealed a marked preferential incorporation of hydrophobic peptides into the plastein fraction. Differential scanning calorimetry results showed only broad peaks which suggested heterogeneous reaction mixtures and products with no well-defined structural elements. These results are entirely consistent with plastein formation proceeding via a purely physical aggregation pathway.     

混杂纤维复合材料的研究进展

混杂纤维复合材料作为一种新型复合材料极大地扩展了复合材料的性能和使用范围.对混杂复合材料拉伸性能、冲击性能、热性能、摩擦性能、阻尼减震性能、吸波性能等方面的研究进展进行了综述,并简要介绍了混杂纤维复合材料的应用情况及发展.     

南瓜籽ACE抑制肽的Plastein反应修饰及分离鉴定

为进一步提升南瓜籽多肽的ACE抑制活性,利用Plastein反应对南瓜籽ACE抑制肽进行修饰,探究底物质量分数、反应温度、反应时间以及3种外源氨基酸添加量对ACE抑制率的影响。采用超滤和Sephadex G-25柱层析等分离修饰产物,并利用LC-MS/MS鉴定肽序列。结果表明：Plastein反应修饰的最佳条件为底物质量分数45%,反应温度20℃,反应时间3 h;分别添加亮氨酸、苯丙氨酸或甘氨酸均能显著提升修饰产物的ACE抑制率,其中添加0.5 mmol/g亮氨酸时,修饰产物的ACE抑制率最高,比修饰前提高了24.50百分点;经超滤和Sephadex G-25柱层析分离,获得ACE抑制率达89.61%的组分,经LC-MS/MS鉴定出76个肽段,固相合成其中4种多肽IFH、IFF、LAAF、DFHPR,其抑制ACE的IC₅₀分别为1.55、2.24、3.79 mmol/L和7.86 mmol/L。综上,Plastein反应修饰可显著改善南瓜籽ACE抑制肽的ACE抑制活性,经超滤和Sephadex G-25柱层析分离,可获得高ACE抑制活性的南瓜籽ACE抑制肽。     

Modification of leaf protein concentrate by the use of plastein reaction

A new approach has been used to modify the unfavourable organoleptic properties of of lucerne leaf protein (LPC), a protein-rich concentrate of high nutritive value. This involved an initial peptic hydrolysis of the dark green, gritty and leaf-flavoured LPC and subsequent re-incubation of this hydrolysate with additional pepsin. A cream coloured, chocolate-flavoured, protein-rich product produced by this plastein reaction was isolated from the second incubate. The various steps involved in this process were optimised with an emphasis on simplest possible techniques. Methods were devised to make more efficient use of the pepsin in the initial hydrolysis and pepsin in the form of an immobilised derivative in paraffin wax has been used. These preliminary studies indicate that more flexibility is offered by plastein reaction for getting a protein-rich product from leaves of desirable qualities than by other methods used hitherto.     

胶原蛋白的应用及其发展前景(续)

结合胶原蛋白的结构特点及性能 ,说明它在生物、医学、食品、化妆品中的应用进展及其前景。     

胶原蛋白的应用及其发展前景

结合胶原蛋白的结构特点及性能 ,说明它在生物、医学、食品、化妆品中的应用进展及其前景