Release Model of Water-soluble Chitosan Nanoparticles for Protein Delivery

[Objective] The experiment aimed to explore release rule of water-soluble chitosan (WSC) in vitro. [Method]The bovine serum albumin(BSA) was taken as a model protein drug and some existing release models such as Kinetics model, Gompertz model, Weibull model, Higuchi model and Logistic model were used to fit the BSA release profile from WSC carriers. [Result] Except Higuchi model and Logistic model, other models could fit BSA release profile better. [Conclusion] Gompertz two-order kinetics model could fit the release of WSC nano-particles better and model parameters had practical physical meaning.

Palatability of Water-Soluble Extracts of Protein Sources and Replacement of Fishmeal by a Selected Mixture of Protein Sources for Juvenile Turbot(Scophthalmus maximus)

Poor palatability is a limiting factor for replacing fishmeal with other protein sources in aquaculture. The water-soluble molecules with low molecular weights are the major determinants of the palatability of diets. The present study was conducted to investigate the palatability of water-soluble extracts from single protein source(single extract pellets) and the mixture of these extracts with different proportions(blended extract pellets) in juvenile turbot(Scophthalmus maximus). Then according to the palatability of blended extract pellets, an optimal mixture proportion was selected, and a new protein source made from raw protein materials with the selected proportion was formulated to replace fishmeal. Summarily, the palatability of single extract pellets for turbot was descendent from fishmeal to pet-food grade poultry by-product meal, wheat gluten meal, soybean meal, peanut meal, meat and bone meal, and corn gluten meal. Subsequently, according to the palatability of single extract pellets, 52 kinds of blended extract pellets were designed to test their palatability. The results showed that the pellets presented remarkably different palatability, and the optimal one was diet 52(wheat gluten meal: pet-food grade poultry by-product meal: meat and bone meal: corn gluten meal = 1:6:1:2). The highest ingestion ratio(the number of pellets ingested/the number of pellets fed) was 0.73 ± 0.03, which was observed in Diet 52. Then five isonitrogenous(52% crude protein) and isocaloric(20 k J g^(-1) gross energy) diets were formulated by replacing 0(control), 35%, 50%, 65% and 80% of fishmeal with No.52 blending proportion. After a 10-weeks feeding trial, a consistent feed intake was found among all replacement treatments. Replacement level of fishmeal up to 35% did not significantly influence final body weight, specific growth rate, feed efficiency ratio, and protein efficiency ratio of turbot. Therefore, the water-soluble extracts of protein sources play an important role in improving the palatability of non-fishmeal protein sources in aquafeed.

Favorable and unfavorable amino acid residues in water-soluble and transmembrane proteins

We analyzed the amino acid residues present in the water-soluble and transmembrane proteins of 6 thermophilic and 6 mesophilic species of the domains Archaea and Eubacteria, and characterized them as favorable or unfavorable. The characterization was performed by comparing the observed number of each amino acid residue to the expected number calculated from the percentage of nucleotides present in each gene. Amino acids that were more or less abundant than expected were considered as favorable or unfavorable, respectively. Comparisons of amino acid compositions indicated that the water-soluble proteins were rich in charged residues such as Glu, Asp, Lys, and His, whereas hydrophobic residues such as Trp, Phe, and Leu were abundant in transmembrane proteins. Interestingly, our results found that although the Trp residue was abundant in transmembrane proteins, it was not defined as favorable by our calculations, indicating that increased numbers of a particular amino acid does not necessary indicate it is a favorable residue. Amino acids with high G + C content such as Ala, Gly, and Pro were frequently observed as favorable in species with low G + C content. Comparatively, amino acids with low G + C content such as Phe, Tyr, Lys, Ile, and Met were frequently observed as favorable in species with high G + C content. These are the examples to increase the supply of amino acids than expected. Amino acids with neutral G + C content, i.e., Glu and Asp were favorable in water-soluble proteins from all species analyzed, and Cys was unfavorable both in water-soluble and transmembrane proteins. These results indicate that amino acid compositions are essentially determined by the nucleotide sequence of the genes, and the amino acid content is altered by a deviation from expectation.

Variation of Protein Content in Tartary Buckwheat Seeds

[Objective]The aim was to select tartary buckwheat materials with high protein content.[Method]Used 35 kinds of tartary buckwheat as experimental material,and the protein content of seeds had been determined.[Result]The protein content of 35 kinds of tartary buckwheat will change in the range of 23.65-193.28 mg/g with an average of 111.85 mg/g.There was difference among different origins of tartary buckwheat.The seeds from Hezhang in Guizhou and Sichuan had highest protein content,while the seeds from Nayong had lowest protein content.[Conclusion]The study had provided theoretical basis for the further study on the genetic and variation law of protein content in different tartary buckwheat resources.

Effects of nitrogen fertilizer on protein synthesis, accumulation, and physicochemical properties in common buckwheat

Nitrogen(N)fertilization affects grain quality in common buckwheat(Fagopyrum esculentum Moench).But the effects of N fertilizer on various buckwheat protein parameters are not fully understood.This study aimed to investigate the synthesis,accumulation,and quality of buckwheat protein under four N application rates in the Loess Plateau,China.Optimal N application(180 kg N ha-1)improved yield,agronomic traits,and N transport and increased protein yield and protein component accumulation.Prolamin and glutelin accumulation first increased and then decreased with increasing N application.The relationships between the contents of protein components and the amount of applied N generally followed quadratic functions.Nitrate reductase and glutamine synthetase activities first increased and then decreased with increasing N levels.Optimal N fertilizer increased the waterholding capacity and thermal stability of buckwheat protein and reduced its emulsification capacity,but negligibly changed its oil-absorption capacity.Hydrophobic amino acids and glutelin content were the main factors affecting protein quality.

Effect of Different Fertilization Patterns on Buckwheat Seed Quality

[Objective] This study aimed to improve the taste and quality of buckwheat（Fagopyrum esculentum） seeds. [Method] Buckwheat seeds were fertilized by using a quadratic orthogonal rotation combination design to establish quaternary quadratic regression equations between N, P, K, organic fertilizers and soluble sugar, protein contents in buckwheat seeds. [Result] According to the regression equations, appropriately increasing the application amount of P fertilizer and maintaining the ratio of N fertilizer to organic fertilizer at 1：140 could improve soluble sugar and protein contents in buckwheat seeds. By simulation optimization using a computer,in order to ensure high soluble sugar and protein contents in buckwheat seeds, the optimal fertilization patterns of each fertilizer were： N, 535.35-581.10 kg/hm^2; P2O5,69.511 5-71.359 5 kg/hm^2; K2 O, 249.525-270.975 kg/hm^2; organic fertilizer, 76 590-80 514 kg/hm^2. The optimal fertilization ratio of N, P, K and organic fertilizers was8：1：4：1 114. [Conclusion] This study provided scientific basis for producing buckwheat products with good taste, high nutrition value and excellent quality.

热处理对荞麦麸皮蛋白结构与理化特性的影响

通过测定热处理前后荞麦麸皮蛋白的分子质量、二级结构、内源荧光光谱、游离巯基与二硫键含量、微观结构、热特性及流变学特性,分析热处理对荞麦麸皮蛋白结构及理化特性的影响。结果表明,热处理促使荞麦麸皮蛋白中部分亚基被降解为小分子质量的多肽或寡肽。α-螺旋结构转变为β-折叠、β-转角和无规卷曲结构,且游离巯基与二硫键含量显著增加。荞麦麸皮蛋白的峰值温度、变性焓值、表观黏度、储能模量以及损耗模量均显著低于大豆分离蛋白;热处理后形成的荞麦麸皮蛋白热凝胶表面更加粗糙,凝胶壁出现明显裂纹,表明荞麦麸皮蛋白热稳定性低于大豆分离蛋白。综上所述,热处理能够改变荞麦麸皮蛋白的结构,并对其理化特性产生不同程度的影响。

苦荞蛋白降血脂肽的酶解制备、氨基酸组成及活性研究

以苦荞麦为原料提取苦荞蛋白,以胰脂肪酶抑制率为指标,通过单因素和响应面优化试验筛选出苦荞蛋白降血脂肽的酶解条件,同时对苦荞蛋白降血脂肽的氨基酸组成和降血脂活性进行研究。结果表明,用菠萝蛋白酶酶解苦荞蛋白得到的降血脂肽对胰脂肪酶的抑制活性更高,其最佳酶解条件为酶解时间2.1 h,酶解温度62.0℃,底物浓度3.23%,pH7.0和酶底比0.4%,在此条件下酶解物的胰脂肪酶抑制率为81.22%±0.16%。氨基酸分析结果显示,苦荞蛋白降血脂肽中必需氨基酸占比27.82%,疏水性氨基酸占比32.11%,酸性氨基酸占比35.86%,精氨酸与赖氨酸的比值为2.28。苦荞蛋白肽显示出良好的体外降血脂活性,其牛磺胆酸钠结合率、胆固醇酯酶抑制率和胰脂肪酶抑制率的EC_(50)/IC_(50)值分别为9.136、3.902和0.051 mg/mL。研究结果为苦荞麦资源的高值化利用和苦荞蛋白活性肽的开发提供了新思路和理论依据。

负载藜麦皂苷Pickering乳液的制备、性质表征和体外消化特性

由于藜麦皂苷具有苦味,对人体黏膜有刺激性作用,研究用新型Pickering乳液递送系统包埋藜麦皂苷。制备了不同藜麦皂苷添加量、大豆油含量的多组乳液。通过表征乳液的包埋率、粒径、流变、微观结构、色度和苦味值对乳液性质进行研究,通过模拟体外消化实验测定负载藜麦皂苷Pickering乳液中藜麦皂苷在消化过程中的释放情况和生物利用率。结果表明,藜麦皂苷含量为1%(w/v)、大豆油含量为80%(v/v)的Pickering乳液(1%-80%)具有最高的包埋率、最小的粒径、最致密的微观结构和最稳定的乳液状态,并且可以有效遮盖藜麦皂苷的苦味。1%-80%组负载藜麦皂苷Pickering乳液在消化过程中藜麦皂苷释放较为缓慢,藜麦皂苷释放百分比较高且其生物利用率较高。因此,1%-80%组负载藜麦皂苷Pickering乳液具有良好的性质,可以作为递送系统包埋藜麦皂苷,在食品工业、医药领域上具有广阔的应用前景。

马铃薯蛋白-黄原胶复合物对荞麦面团发酵特性的影响

研究在不同pH条件下(2.67、4.69、7.48)制备的马铃薯蛋白-黄原胶复合物(PP-XGC)的疏水性、乳化性和起泡性及其对荞麦面团发酵特性的影响。结果表明:PP-XGC的起泡性、泡沫稳定性、乳化性和表面疏水性随着pH的升高而增加;与对照组(未添加PP-XGC的荞麦面团)相比,添加PP-XGC降低了面团的黏度和回生值,增加了面团的发酵高度,改善了面团的稳定性和抗老化性。二级结构分析表明,与对照组相比,β-转角含量和无规则卷曲含量上升。拉曼光谱分析表明,PP-XGC的添加可以改善荞麦面团的发酵特性。微观结构分析表明,在pH 2.67条件下PP-XGC添加量(以荞麦粉质量为基准)为1.0%时,面团品质更佳。

谷氨酰胺转氨酶介导的荞麦蛋白-花生蛋白交联及其功能特性研究

以谷氨酰胺转氨酶(TGase)为交联酶制剂,对荞麦蛋白与花生蛋白进行交联,通过单因素实验对2种蛋白的比例、总蛋白质质量浓度、TG酶添加量、交联温度、交联时间和pH进行了参数优化,并研究了最佳交联工艺条件下制备得到的交联产物的功能特性。结果表明,荞麦蛋白与花生蛋白的质量比1∶1、总蛋白质量浓度4 g/100 mL、酶质量分数1.25%、反应温度40℃、反应时间120 min、pH 8.0时的交联反应效果最佳,交联度为63.1%。功能特性测定结果表明,与未交联的蛋白质相比,交联后的蛋白质的持水性、持油性和乳化稳定性有所提高,但乳化性、起泡性和起泡稳定性降低;在pH 3~12范围,交联蛋白质的溶解度逐渐升高,尤其在pI 4.0处,溶解度提高最为显著。

碱性蛋白酶水解萌动苦荞蛋白质的条件优化

以萌动苦荞蛋白质和碱性蛋白酶为试验材料,通过单因素和正交试验研究碱性蛋白酶水解萌动苦荞蛋白质过程中温度、pH值、加酶量对水解效果的影响。结果表明,碱性蛋白酶水解萌动苦荞蛋白质的最佳条件为控制水解温度45℃、pH值10、加酶量2000 U·g^(-1)、水解120 min,该条件下水解度为20.13%。

基于区别化熟化处理方式的荞麦粉蛋白影响性研究

采用碱溶酸沉法提取荞麦蛋白并对其工艺条件进行优化,通过蒸制、煮制和炒制三种方式对荞麦进行熟化。在最佳工艺条件下制备了四种蛋白溶液,选用考马斯亮蓝法对荞麦蛋白的含量和功能特性进行测试。实验结果表明,最佳提取工艺条件:料液比为1∶15,pH值为10,提取温度为55℃,提取时间为140分钟。各处理方式的荞麦蛋白含量中,煮制清蛋白含量最高(32.8%),未熟化荞麦中谷蛋白含量最多(38.9%),醇溶蛋白含量则在煮制荞麦中最低(6.4%)。未熟化荞麦中球蛋白溶解度最高(33.7%),而谷蛋白和醇溶蛋白的溶解度略有变化或下降,煮制和蒸制后清蛋白和球蛋白的溶解度明显提高。荞麦谷蛋白的持水性最佳,煮制和蒸制后各蛋白的持水性相对提高。煮制后,清蛋白、谷蛋白和球蛋白的吸油性相对提高。研究有助于为荞麦精准深加工提供理论依据和推动产业发展。

荞麦蛋白的功能特性研究

采用碱萃取酸沉析法提取制备了荞麦蛋白,并较为系统地研究了蛋白质浓度、温度、pH值、氯化钠和蔗糖对荞麦蛋白的三种功能特性(溶解性质、乳化特性和泡沫特性)的影响。结果表明,本实验条件下制备的荞麦蛋白具有优良的溶解性质,其乳化性质与对照样品大豆分离蛋白相当,但泡沫特性较差。

双缩脲法测定荞麦蛋白质

本文介绍了一种双缩脲试剂和分析方法。探讨了如何正确使用它测定荞麦蛋白质含量。结果表明:①这种试剂和方法适用面宽、精密度高、回收率>95%,采用牛血清蛋白为标准物质制作标准曲线时,分析结果中的蛋白质为碱液可溶性蛋白质,采用代表性很强的样品(已知其总蛋白质含量)为标准物质制作标准曲线时,分析结果中的蛋白质为总蛋白质。②白花荞麦仁中总蛋白质含量为11.6%,脱除麦仁表层所留下的麦仁内部的蛋白质含量为5.6%,荞麦仁的碱液可溶蛋白的含量为7.6%,脱除麦仁表层所留下的麦仁内部的减液可溶的蛋白质含量为2.5%。

萌发荞麦种子蛋白质组分含量变化的研究

研究了荞麦种子萌发后总蛋白质和各蛋白组分如清蛋白、球蛋白、醇溶蛋白和谷蛋白的含量变化 ,结果表明 :本试验条件下 ,山西甜荞和四川苦荞萌发后总蛋白质含量呈逐渐下降趋势。山西甜荞经过 72h的萌发 ,其蛋白质总量由最初的 11.90 %下降到 5 .4 4% ,下降了 6 .5个百分点。四川苦荞由萌发初的 6 .5 3%下降到 0 .96 % ,下降了 5 .6个百分点。荞麦清蛋白和球蛋白在萌发后均呈现下降趋势 ,与总蛋白质含量变化相一致。谷蛋白在萌发后至 36h内含量下降 ,之后又快速增加。四川苦荞醇溶蛋白含量在萌发后逐渐增加 ,而山西甜荞则有逐渐下降趋势。

荞麦蛋白研究进展

荞麦具有较高的营养价值和药用价值。荞麦蛋白是荞麦中的主要生物活性成分,它具有特殊的结构、生理功能以及加工功能特性,在食品加工中有着广泛的应用前景。本文就荞麦中蛋白质的含量、蛋白质的结构组成、蛋白质的质量、蛋白质的生理功能、蛋白质的加工功能特性以及营养特性进行了论述,以期推动我国荞麦研究的进一步发展,加快我国荞麦资源的开发利用。

响应面法优化荞麦蛋白酶解工艺

以荞麦蛋白为研究对象,在单因素试验基础上,采用响应面分析法优化荞麦蛋白酶解工艺。结果表明:水解温度64℃、pH9、酶用量3704U/g、底物质量浓度7.8g/L,荞麦蛋白的水解度达到最大值。该条件下荞麦蛋白水解度预测值为37.43%,验证实验所得实际值为37.35%,实测结果与预测值符合良好。

荞麦籽粒蛋白质组分特性研究

采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）方法研究了荞麦的2个栽培种苦荞与甜荞的总蛋白、清蛋白、球蛋白及谷蛋白特性。试验结果表明,甜荞籽粒总蛋白及蛋白质各组分的谱带具有丰富的多态性,而苦荞籽粒总蛋白及蛋白质各组分谱带的多态性有限;荞麦清蛋白主要由低分子量的亚基构成;甜荞球蛋白组分包含由中等到低分子量范围的5-12种亚基,苦荞球蛋白主要由8种亚基组成;甜荞谷蛋白主要由分子量在43-66.2 kDa之间的3-5种亚基组成,苦荞谷蛋白主要由分子量在31-43 kDa间的2种亚基组成。

拉曼光谱分析荞麦多酚对米糠蛋白结构的影响

利用拉曼光谱研究荞麦多酚对米糠蛋白的影响。结果表明:随着荞麦多酚添加量增加,米糠蛋白结构变化规律为α-螺旋结构含量逐渐降低,β-折叠结构含量呈现先增加后降低的变化趋势,β-转角结构含量呈先降低后增加的变化趋势,而无规则卷曲结构的含量逐渐增大;酪氨酸及色氨酸先趋于"暴露式"而后转为"包埋态",而荞麦多酚的添加使米糠蛋白二硫键由gauche-gauche-trans构型和trans-gauche-trans构型逐渐转变为gauche-gauche-gauche构型。因此,荞麦多酚与米糠蛋白的交互作用可部分破坏米糠蛋白分子间二硫键,降低米糠蛋白分子间作用,增强米糠蛋白结构的稳定性。