酶法疏水修饰大豆球蛋白对其色素结合能力的影响

为提高天然红曲色素的光稳定性,利用具有严格底物专一性的谷氨酰内肽酶对大豆球蛋白（11S）进行轻度水解,分析了11S酶解后表面疏水性的变化,并将水解产物与红曲色素形成蛋白/色素复合体,对两者之间的结合特性（结合常数、结合量）和复合体的光稳定性进行了研究。研究发现,谷氨酰内肽酶对11S的表面性质及红曲色素稳定性均具有显著影响。经谷氨酰内肽酶修饰后,由于内部疏水基团的暴露,11S的表面疏水性随水解度的增加而增加,与红曲色素的结合位点也随之变多。在中性条件下,水解度为1.50%、质量分数为3%的11S与红曲色素的结合常数达到最大值,最大结合量为215.00 U/g pro。复合体经24 h光照后,红曲色素的色价保留率达90%,大大提高了红曲色素的光稳定性。     

Glucose,fructose and sucrose increase the solubility of protein–tannin complexes and at high concentration,glucose and sucrose interfere with bisulphite bleaching of wine pigments

Wines were modified with increasing sugar concentrations and decreasing tannin concentrations and analysed by a combination of protein precipitation and bisulphite bleaching. Increasing sugar concentration decreased the precipitation of tannin and protein-precipitable polymeric pigments (PPP). The use of a hydrogen bond disruptor (urea) to reduce protein–tannin and protein–pigment complex formation showed that the effect of sugar concentration occurred by increasing the solubility of the tannin–protein complex, not by interfering with protein–tannin complex formation. By increasing the solubility of pigment–protein complexes, non-protein-precipitable polymeric pigments (nPPP) appeared to increase. There was also an increase in total polymeric pigments at each tannin concentration with increasing glucose and sucrose concentration, indicating that sugar concentration might also affect bisulphite bleaching of wine pigments. While a significant effect of sugar concentration on tannin–protein complex solubility was observed, these effects were greatest at sugar concentrations far in excess of normal wine making conditions. Under normal wine making conditions, sugar concentration will have a negligible effect on protein-precipitable tannin, PPP and nPPP concentrations.     

Astaxanthin Extraction from Shrimp Wastes and its Stability in 2 Model Systems

Abstract: The objective of this work was to study the stability of astaxanthin, obtained from shrimp wastes, and incorporated to 2 model systems: egg albumin protein solution and sunflower oil. Shrimp wastes were ensiled by a treatment with formic/acetic acids (4%–4% v/w wastes) and stored at 4 °C for 24 h. The pigment was extracted with organic solvents (petroleum ether:acetone:water, 15 : 75 : 10) and concentrated. The storage parameters studied were: illumination (light/dark), temperature (4/20 °C), atmosphere (air/air-free), and storage time (0, 1, 2, 3, 4, 5 wk). Results showed that total xantophylls and astaxanthin were more stable in sunflower oil than in the protein system. Total xantophylls showed more stability than astaxanthin, possibly due to the presence of other, more stable carotenoids quantified together with xantophylls. Astaxanthin concentration was significantly affected by storage time; its degradation followed a first-order reaction rate under all the studied conditions. This pigment was stable only for 17 d, even when stored in air-free flasks, under refrigeration, and in the dark. Practical Application: Shrimp catching and farming generate large amounts of polluting wastes; they can be an important source of added-value red-orange pigments. However, these pigments are highly unstable to various transformation processes and to storage conditions. This research studied the effect of storage on 2 model systems (protein and lipid) on pigment degradation.     

PROPERTIES OF BIXIN AND NORBIXIN AND THE COMPOSITION OF ANNATTO EXTRACTS

SUMMARY— The melting point and ₁ ^1% _cm-values of a-bixin, β-bixin, and a-norbixin were determined and the stability of a-bixin examined under different conditions. The total pigment content of butter colors was determined. a-Bixin was the principal pigment; in addition, at least eight different pigments were present. The content of a- and β-bixin in butter colors was also determined. Because of complex formation of bixin and norbixin with a yellow pigment, the simple chromatographic method became rather laborious. This complex formation did not occur in the annatto suspensions in oil and fat. These preparations were more concentrated, while the amount of decomposition products of a-bixin was relatively slight. The stability of the pigments in butter colors appeared to be great. Investigation of annatto cheese colors showed that these extracts contain at least seven color components. The total amount of red pigment and the principal pigment a-norbixin were determined.     

多光谱学与分子模拟技术表征甜菜苷与乳清蛋白的相互作用

为研究甜菜苷（Betanin）与乳清分离蛋白（Whey protein isolate, WPI）的相互作用及乳清分离蛋白对甜菜苷热稳定的影响，本文通过自组装法构建了WPI-Betanin复合物，利用紫外可见光谱验证了复合物的形成，并通过荧光光谱和圆二色谱探究了复合物形成的作用机制及蛋白质结构的变化，最后采用分子模拟技术将复合物相互作用可视化。结果表明，甜菜苷与乳清分离蛋白主要通过氢键与范德华力形成复合物，结合位点数约为1。复合物的形成导致蛋白的浊度增加，表面疏水性降低，内源荧光猝灭，且猝灭机制为静态猝灭，常温下的猝灭常数为1.78×103 L/mol。相互作用改变了乳清分离蛋白中色氨酸、酪氨酸的微环境和二级结构含量，使甜菜苷在80 ℃下加热1 h的保留率从6.17%提高到27.26%。本研究为功能性蛋白色素复合物的应用开发和甜菜苷的护色提供了理论基础。     

板栗壳棕色素的抗氧化活性及其活性成分的分离、鉴定

板栗壳棕色素是一种重要的天然食用色素,本文研究了其光谱特性、抗氧化活性和化学成分组成,为板栗壳棕色素的深入应用提供依据。利用碱提酸沉等方法从板栗壳中提取出板栗壳棕色素,紫外和红外光谱法初步确定其光谱特性,并采用Folin-Ciocalteu法、苯酚-硫酸显色法和BCA法测定棕色素中总多酚、多糖和蛋白质的含量。以DPPH自由基清除法测定棕色素的抗氧化活性,采用色谱法分离纯化其中的化合物,并通过液相色谱、质谱与核磁对其进行鉴定。结果表明,板栗壳棕色素的水溶液在276 nm波长有最大吸收,红外光谱图显示出明显的多酚类物质特征。棕色素中总多酚、多糖和蛋白质含量分别为42.35%、13.75%和8.08%。棕色素对于DPPH自由基的IC₅₀为0.44 mg/mL,具有较强的抗氧化能力。从棕色素中分离得到10个多酚类化合物,分别为间苯二酚(1)、2-羟基-3',4'-二羟基苯乙酮(2)、邻苯二酚(3)、原儿茶醛(4)、没食子酸甲酯(5)、2,5-二羟基苯乙酮(6)、β-羟丙基香草酮(7)、原儿茶酸甲酯(8)、对香豆酸(9)和阿魏酸(10)。     

大孔树脂吸附桦褐孔菌多糖色素的机理及工艺优化

为探究大孔树脂吸附桦褐孔菌多糖色素动力学与热力学特征及最佳工艺条件,本实验通过水提醇沉、Sevag法除蛋白、透析制备桦褐孔菌多糖,采用静态吸附实验筛选色素吸附率及多糖保留率评分最高的大孔树脂,研究其吸附动力学与热力学特性,并优化该大孔树脂在动态吸附桦褐孔菌多糖色素中的径高比、吸附时间、上样量以及洗脱流速,确定最佳工艺条件。结果表明,实验筛选的17个不同型号大孔树脂中,大孔树脂HPD-500最为适宜,其吸附色素的过程符合准二级动力学模型,反应过程中受颗粒内扩散与液膜扩散的影响;并且吸附过程符合热力学Freundlich模型,为多分子层吸附,其中吸附焓变>0为吸热反应,吉布斯自由能<0为自发反应,吸附熵变>0为熵增反应。HPD-500吸附色素的最佳条件为径高比1:10,吸附时间1 h,上样量10 mg,洗脱流速1.5 mL/min。在此条件下,桦褐孔菌的色素吸附率为83.15%,多糖保留率为78.89%,多糖纯度由20.40%提升至56.52%。HPD-500大孔树脂具有吸附桦褐孔菌多糖中色素、提高多糖纯度的能力,本文为桦褐孔菌资源高效利用提供了理论及实验基础。     

动物蛋白与植物蛋白对甜菜苷的热保护作用机制研究

为探究不同蛋白质对甜菜苷的热保护作用,明晰其保护机制,本文拟采用两种动物蛋白(乳铁蛋白和β-乳球蛋白)、两种植物蛋白(大米蛋白和大豆分离蛋白)为原料,采用浊度、紫外光谱、粒径、分子模拟等手段表征蛋白-甜菜苷复合物的形成和相互作用机制。结果表明,四种蛋白质均能提高甜菜苷的热稳定性,保护效果为:乳铁蛋白>大豆分离蛋白>β-乳球蛋白≈大米蛋白,蛋白质对甜菜苷热稳定性的提高与蛋白-甜菜苷复合物的形成有关。通过浊度、紫外光谱、粒径的实验结果推测,甜菜苷与乳铁蛋白、β-乳球蛋白、大豆分离蛋白的结合程度高于大米蛋白,这可能是由于大米蛋白的低溶解度和紧密结构造成的。此外,相互作用和分子对接的结果显示,乳铁蛋白与甜菜苷主要通过氢键和静电相互作用结合,β-乳球蛋白与甜菜苷主要通过氢键发生相互作用,大米蛋白与甜菜苷主要通过疏水相互作用结合,大豆分离蛋白与甜菜苷主要通过氢键和静电相互作用结合。本研究为蛋白-天然色素的相互作用及甜菜苷的护色研究提供理论基础。     

大米活性肽研究进展

在我国,稻米除用作主食外,也作为发酵与酿造等工业原料,在米淀粉、味精、色素和酿造等加工产生残渣中富含米蛋白,但目前尚未能得到充分利用而污染环境;稻米蛋白是生产活性肽优质资源之一,活性肽以种类丰富、功能明显、使用安全等特点而成为研究与开发热点。该文综述以稻米蛋白为来源活性肽的研究进展及其开发前景。     

紫胶色素的稳定性

为给紫胶色素在纺织品染色应用中提供理论参考,采用可见分光光度法研究天然染料紫胶色素在不同温度、pH值、金属离子、氧化剂、还原剂条件下的稳定性。结果表明:紫胶色素颜色随着溶液pH值的改变而变化;在酸性条件下温度对色素的影响较小;氧化剂、还原剂以及碱性条件对稳定性影响较大;Ca2+、Cu2+、Al3+、Fe3+、Fe2+、Zn2+、Sn2+等金属离子可与紫胶色素形成配合物,色素的颜色会发生改变,红外光谱证明紫胶亚铁离子配合物的形成。     

小麦籽粒颜色与营养特性的相关研究

研究了白、红、紫、深紫、紫黑、蓝等不同颜色小麦籽粒的营养特性，并分析了其与色素含量之间的关系。结果表明，小麦籽粒颜色与其营养特性之间存在着非常密切的关系。紫、深紫、紫黑、蓝等黑粒小麦籽粒的色素含量显著或极显著的高于普通白粒和红粒小麦，可溶性蛋白含量、粗蛋白含量、总氨基酸含量、Vc含量和类胡萝卜紊含量等营养指标高于白粒和红粒小麦，可溶性糖含量则低于白粒和红粒小麦；相关性分析结果表明，可溶性蛋白含量、粗蛋白含量、总氨基酸含量、Vc含量和类胡萝卜紊含量与色素含量呈正相关，可溶性糖含量与色素含量之间呈负相关。     

A bioactive complex to protect proteins from UV‐induced oxidation in human epidermis1

UV light induces multiple damages including protein oxidation on skin. Oxidized proteins if not degraded by the proteasome would eventually accumulate causing metabolic damage, elastosis and pigment formation such as lipofuscin. During ageing, the activity of the proteasome decreases dramatically together with enzymes that protect from oxidation and as a result oxidized proteins accumulate. We have investigated a combination of Panthenyl triacetate and Ethyl linoleate (bioactive complex) to fight against protein oxidation. This complex when tested at 3% on human skin biopsies showed statistically significant protection from UV (UVA + UVB)‐induced protein oxidation both in a 24‐h pre‐treatment before UV irradiation (72% protection, P < 0.05) and immediately after irradiation (78% protection, P < 0.05). UV light also induced a significant decrease of mRNA for protein repairing enzymes, such as Methionine Sulfoxide Reductase (MSR). The complex, given both pre‐ and post‐irradiation, stimulated the repairing enzyme expression. We can suggest utilization of this new complex to prevent accumulation of oxidized protein as a result of skin photo‐ageing and to prevent stratum corneum dehydration, skin elastosis and pigmentation formation (age spots).     

Extraction and quantification of main pigments in pesto sauces

Pesto is a widely diffused Italian pasta sauce, whose main ingredient is basil. Since its appearance is a key factor for marketing, the determination of its pigment content is of fundamental interest. To this aim, a method for the determination of pesto pigments by C18-HPLC is proposed. Only β-carotene was determined directly by Vis-spectrophotometry, as a consequence of sample purification over a silica cartridge. The proposed method is reliable allowing, for the first time, an easy determination of chlorophylls, pheophytins, lutein and β-carotene in a complex matrix such as pesto. The results show great differences in pigment composition among the samples, with pheophytins as the main components. Only non-thermally processed product show appreciable chlorophyll content as a consequence of the different production technique. Principal Component Analysis performed on the pigment contents showed great variability among the different samples.     

紫甘薯花色苷生产中紫薯蛋白的分离与富集

为了将紫甘薯色素提取液中的花色苷与蛋白分离,选择不同型号的大孔吸附树脂对紫甘薯色素提取液进行了吸附与解吸实验,筛选出特异性吸附提取液中色素的树脂.并利用大孔吸附树脂对流出液中紫甘薯蛋白进行富集.实验结果表明:ADS-7型树脂能有效将提取液中的花色苷与蛋白分离,分离程度达70%以上;流出液以1BV/h、2mg/mL流经树...     

玉米黄色素萃取工艺优化研究

以玉米淀粉副产物玉米黄浆粉为原料,采用不同的有机溶剂从玉米黄浆粉中提取玉米黄色素,并利用单因素和正交试验来确定最佳因素和工艺条件。结果表明,温度对玉米黄色素提取率的影响最大,其次是提取时间,而料液比的影响较小。其最佳工艺条件为:以无水乙醇为提取剂,料液比为1 15,提取温度为70℃,提取时间为1.5h,玉米黄色素的提取率为56.84%。     

薯莨色素的提取工艺及基本成分和抗菌活性研究

目的探讨薯莨色素的提取工艺,研究其基本成分和抗菌活性。方法以60%丙酮为提取剂,料液比(w/v)1:10,常温浸渍5 h,60℃水浴回流3 h,提取薯莨色素;测定其水分、灰分、粗蛋白、粗脂肪及粗纤维等含量;并以大肠杆菌、桉树青菇菌、巴氏杆菌、蜡状芽孢杆菌、芽孢杆菌、沙门菌为供试菌,检验提取薯莨色素的抗菌活性。结果薯莨色素提取率达28.6%;薯莨色素基本成分为:水分22.61%,灰分1.61%,粗脂肪2.89%,粗纤维2.80%,粗蛋白3.80%;薯莨色素浓度在0.1%~0.50%范围内对6种供试菌种皆显示了不同程度的抑制效果。结论薯莨色素是具有抗菌活性的天然色素,具有一定的开发价值。     

薯莨水溶提取组分的初步分析

为了研究薯莨色素提取液的成分,利用凝胶过滤柱色谱法对薯莨水溶提取组分初步分离得到2类组分：乳白色物质和深棕色色素物质。应用诊断试剂、紫外光谱、红外光谱对分离所得的乳白色物质和色素物质进行定性,并结合基质辅助激光解吸飞行时间质谱分析发现：纯水提取的薯莨色素主要是缩合单宁四聚体以下的多聚体;乳白色物质主要是多糖类物质,含有果胶和淀粉,不含蛋白质。采用香草醛-盐酸法和苯酚-硫酸法对提取物中的缩合单宁和乳白色物质中多糖进行定量分析发现,二者在薯莨提取物中的平均含量分别为47.7%和10.2%。     

高产红曲色素的紫红红曲霉诱变育种技术研究

以紫红红曲霉为出发菌株,通过物理(紫外线、超声波、微波)诱变和化学(氯化锂)诱变的方法来选育红曲色素高产菌株,实验过程中分别采用单一的诱变方法和复合诱变方法(2～4种诱变方法相结合)来处理出发菌株,选育出红曲色素高产菌株。试验结果表明,各种诱变方法对紫红红曲霉产红曲色素的能力都有不同程度的提高,其中以2种诱变方法相结合的方式对红曲霉产红曲色素能力提高最为明显,如紫外和超声波复合诱变的方法产红曲色素的色价为922U/mL,比出发菌株产红曲色素的能力提高了约3倍。但随着各结合方法的增多,诱变菌株产色素能力逐渐下降。     

藻类色素蛋的资源开发和应用研究

大海是一个宝库,蕴含着大量的海洋生物,其中各种颜色的藻类蕴含着丰富的蛋白质资源,是食品理想的蛋白源,但是人类目前所利用的仅为其中很少的一部分。作为藻类捕光色素的藻胆蛋白是藻类蛋白中的主要成分,是一种水溶性色素蛋白。藻胆蛋白所包含的藻红蛋白、藻蓝蛋白以及别藻蓝蛋白均具有一定的荧光特性,并分别呈现红色、蓝色和紫罗兰色的荧光,因此藻胆蛋白也是理想的天然色素添加剂。近年来由于合成色素添加剂所存在的一些隐患问题以及出现的一系列问题使得寻求天然色素添加剂尤为重要。而藻胆蛋白作为一种蛋白质同时又具有色素特征而深受食品加工业青睐,但是由于自身有一定的缺点,因此如何利用海藻色素蛋白是目前海藻加工业的一个热点问题,本文从藻胆蛋白的组成、光谱特性、稳定性和应用等方面进行简单论述。     

米糠蛋白提取中褐变抑制剂的筛选

米糠蛋白是一种低过敏性的优质植物性蛋白,但制备过程中常伴随褐变反应的发生,导致制备出的米糠蛋白成品颜色深,限制了米糠蛋白在食品及相关领域的广泛应用。本文以米糠为原料,分别采用碱法和复合法提取米糠蛋白,在提取米糠蛋白的过程中分别加入各种不同的抑制剂,以抑制褐变反应。碱法提取米糠蛋白过程中,最佳抑制剂为1.5%的次氯酸钠,色素抑制率为64.2%,蛋白提取率为53.7%;复合法中,以3.0%的抗坏血酸、1.0%的次氯酸钠和0.15%的L-半胱氨酸为最佳复配抑制剂的情况下,提取出的米糠蛋白颜色浅,此时色素抑制率为69.87%,蛋白提取率为80.06%,褐变抑制效果显著,蛋白提取率高。