等电点沉淀提取蛋白和漂洗鱼糜蛋白的高温胶凝特性

研究不同加热温度(100、110、120℃)和时间(15、30、60 min)对等电点沉淀法(isoelectric solubilization precipitation,ISP)提取蛋白与漂洗鱼糜蛋白高温胶凝特性的影响,以白鲢为原料,分别测定凝胶强度、持水性、色泽、化学作用力、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳。结果表明,ISP蛋白凝胶的破断力低于漂洗蛋白凝胶,凹陷深度高于漂洗蛋白凝胶。漂洗蛋白凝胶和ISP蛋白凝胶获得最高凝胶强度的热处理温度分别为110℃和100℃。随着加热时间的延长,凝胶的破断力和凹陷深度降低。ISP蛋白凝胶的持水性不受热处理条件的影响,而漂洗蛋白凝胶的持水性随加热时间的延长而降低,ISP蛋白凝胶的持水性低于漂洗蛋白凝胶。漂洗蛋白凝胶的亮度值(L*)和白度值(W)高于ISP蛋白凝胶,随着加热时间的延长,漂洗蛋白凝胶的L*值和W值呈下降趋势,而ISP蛋白凝胶的L*值和W值呈上升趋势。高温处理过程中,ISP蛋白凝胶和漂洗蛋白凝胶的离子键和氢键含量呈先上升后下降趋势,而疏水相互作用和总巯基含量整体呈下降趋势;漂洗蛋白凝胶和ISP蛋白凝胶的肌球蛋白重链条带消失,肌动蛋...     

鱼糜加工废水中蛋白质回收工艺的优化

针对目前鱼糜加工企业排放废水中含有的大量蛋白质,通过选取一种絮凝剂,以其添加量、絮凝温度、絮凝时间、絮凝pH值进行单因素实验,然后用Design-Expert软件的Box-Behnken中心组合设计进行四因素三水平响应面实验。结果表明:三氯化铁添加量0.13 g/L,絮凝温度18.44℃,时间5 h,pH 5.44,此时蛋白质回收率最高,达86.94%。该法具有蛋白质回收率高,回收蛋白质安全卫生,操作简便,成本低等特点。     

荧光法检测鱼糜制品中大豆蛋白的研究

鱼糜制品中大豆蛋白的过量添加已成为水产食品生产的一个新问题,建立有效的检测方法尤为重要。本研究通过丙酮浸泡、酸处理、硫酸铵盐析和柱层析等步骤分离纯化大豆胰蛋白酶抑制剂（Soybean trypsin inhibitor,STI）并制备抗STI单克隆抗体（A11-6）。经过Protein G Sepharose柱层析分离得到高纯度的免疫球蛋白（IgG）。采用SPDP（N-琥珀酰亚氨基-3-2-吡啶）和DTT（二硫苏糖醇）组合处理,成功将R-藻红蛋白偶联到抗STI单克隆抗体。利用该荧光标记的抗体建立的免疫荧光法能够检测出鱼糜制品中的STI,检测限为1.56μg/mL,灵敏度略高于传统的化学发光法。该免疫荧光法具有操作时间短、灵敏度高和使用安全等优点。      

酸沉淀法回收木薯黄浆废水中蛋白质及其影响因素的研究

以木薯黄浆废水为研究对象,分析木薯黄浆废水主要组成成分,并对其中的蛋白质组分进行有效地沉淀。通过实验测定木薯黄浆废水蛋白质的等电点在3.5~4.5之间。通过单因素实验条件,选择pH、沉淀时间、温度和黄浆废水蛋白质浓度为变量,利用正交实验分析影响木薯黄浆废水蛋白质沉淀因素主次和优化木薯黄浆废水蛋白质酸沉淀工艺,结果表明在pH为4.0、温度为35℃、提取时间为3.0h及蛋白质浓度为1400mg/L的条件下,木薯黄浆废水中蛋白质沉淀率达到最高为98.3%。木薯黄浆废水沉淀蛋白质富含15种氨基酸,可以作为动物饲料添加剂使用。      

复合亲水胶体对带鱼鱼糜制品凝胶特性的影响

本文研究了六种亲水性胶体对带鱼鱼糜制品凝胶特性的影响,以凝胶特性、持水力和白度等为指标,结合扫描电镜观察微观结构,应用响应面法开发鱼糜制品复合型凝胶增强剂。结果表明:在带鱼鱼糜中加入褐藻胶、魔芋胶、沙蒿子胶、卡拉胶、热凝胶多糖均可提高带鱼鱼糜的凝胶强度,加入瓜尔豆胶降低带鱼鱼糜制品凝胶强度。响应面分析得到添加0.1%热凝胶多糖、0.19%魔芋胶、0.1%沙蒿子胶的带鱼鱼糜凝胶制品能够形成均匀、致密的三维网状结构,其凝胶强度是不添加亲水性胶体的3.58倍。      

骨蛋白水解物对冷藏鱼糜品质和蛋白结构特性的影响

通过测定不同贮藏时间内（0、1、3、5、7d）鲤鱼鱼糜的颜色（白度值、亮度值）、硫代巴比妥酸值、挥发盐基氮,及肌原纤维蛋白的ATPase酶活性、表面疏水性、总巯基含量等指标的变化,研究冷藏（4℃）条件下骨蛋白水解物对鲤鱼鱼糜的抗氧化效果及对蛋白的保护作用。结果表明,随着骨蛋白水解物添加量的增加,鱼糜色泽明显改善,鱼糜样品的TBRAS、TVB-N及表面疏水性呈下降趋势;而Ca2+-ATPase酶活性、总巯基含量呈上升趋势。其中添加7%骨蛋白水解物的样品效果最为明显,冷藏至第7d时,与对照组相比,样品的TVB-N及表面疏水性分别降低了1.30g/100g、1.80μg,且效果显著（p<0.05）。因此,骨蛋白水解物能够抑制淡水鱼鱼糜的蛋白和脂肪氧化变性,且浓度越高效果越明显。      

核磁共振技术研究不同漂洗工艺对草鱼鱼糜的影响

利用核磁共振技术研究清水漂洗、盐水漂洗及碱水漂洗对草鱼鱼糜的影响。结果表明:清水和盐水漂洗可以提高草鱼鱼糜的凝胶强度,碱水漂洗会降低草鱼糜的凝胶强度;三种漂洗方法均能提高草鱼鱼糜的持水性,其中盐水漂洗的效果最佳,三种方法均在一次漂洗后达到最佳持水性;一定浓度的盐水漂洗会将一部分盐溶性蛋白溶出,但不会过度溶出;通过正交实验得出最佳漂洗方案为两次水洗一次盐洗,共三次漂洗的方法。      

絮凝法去除谷氨酸等电上清液中菌体蛋白的研究

本文针对谷氨酸生产过程中各种料液（发酵液、等电上清液或离交高流液等）的特性,选择等电上清液为研究对象,以聚丙烯酸钠为絮凝剂去除其菌体蛋白,通过对菌体蛋白絮凝及其絮凝条件选择的研究,获得了82．3％的菌体蛋白去除率和96．68％的谷氨酸回收率。     

鲢鱼鱼糜蛋白质凝胶特性的研究

研究了鲢鱼鱼糜在不同的加热条件下 ,其凝胶的色泽、强度及显微结构的变化。结果表明 ,鲢鱼鱼糜在 60℃时达到较理想的色泽 (白色 ) ,较佳的凝胶条件为 ,先经过 3 5～ 40℃、60min的凝胶化 ,再经过 85℃、3 0min加热。在 5 0℃加热时 ,出现凝胶劣化现象     

Flocculation-enhanced protein recovery from fish processing by-products by isoelectric solubilization/precipitation

Muscle proteins were recovered from rainbow trout processing by-products (fish meat leftover on bones, head, skin, and etc.) by isoelectric solubilization/precipitation. Muscle proteins precipitated at pH 5.5 are typically recovered by high-speed centrifugation at a laboratory scale, which appears to impede process scale-up. Our objective was to investigate the effect of flocculants on separation of precipitated proteins from process water (supernatant). Flocculants with different surface charge properties and molecular weights (M_w) were added to precipitated proteins. Protein separation was evaluated by determining optical density (OD) of the supernatant using Bradford dye-binding method. A high M_w anionic flocculent at 100 mg/L resulted in excellent protein separation following 10 min reaction. The OD of the supernatant was comparable to that of clear water, suggesting that even water-soluble fish muscle proteins were removed from the process water. Freeze-thaw cycles, commonly encountered in the fish processing industry, resulted in even more rapid flocculation reaction. This flocculent could be added to a bio-reactor that precipitates muscle proteins at pH 5.5 in a continuous isoelectric solubilization/precipitation system. However, effects of the flocculants on human and animal health should be determined and appropriate approvals obtained before the recovered muscle proteins can be used in human food products and/or animal feeds.     

Emulsifying properties of soy protein isolate fractions obtained by isoelectric precipitation

Soy protein isolate (SPI) fractions were produced by isoelectric precipitation based on results of isoelectric focusing carried out on the crude soy extract. The fractions were produced from crude protein extract (pH 9.0) sequentially and non‐sequentially at isoelectric points (pIs) of 5.6, 5.1 and 4.5. Emulsions stabilised by soy proteins with pIs between 5.6 and 5.1 had the highest (P < 0.01) emulsion stability index (ESI), while those stabilised with proteins having pIs between 5.1 and 4.5 resulted in the lowest ESI for sequentially precipitated fractions. Non‐sequential fractionation at pI 5.1 produced fractions with higher emulsifying activity index (EAI) than sequential fractionation. SDS‐PAGE profiles indicated that the fractions exhibiting high functionality in terms of ESI and EAI were also richer in 7S globulin protein subunits. © 2001 Society of Chemical Industry     

Gelation properties of goose liver protein recovered by isoelectric solubilisation/precipitation process

Isoelectric solubilisation/precipitation (ISP) process was applied to goose liver (GL) for protein extraction. The gelation properties of proteins extracted by acid processes (ACP, pH 2.0, 2.5 and 3.0) and alkaline processes (ALP, pH 11.0, 11.5 and 12.0) were estimated, where the unextracted ground GL was set as the control. Nearly 58.39~79.00% of GL proteins were recovered by ISP treatments. High molecular weight (100~250 kDa) proteins were found to be partially hydrolysed by ACP, while few changes in proteins occurred during ALP. As evidenced by rheological and textural measurements, ALP proteins formed gels with high elasticity and superior texture, whereas ACP proteins had inferior gelation properties. Moreover, ALP proteins were able to form a highly interconnected and homogeneous three‐dimensional microstructure. Predominantly, gels produced by 11.0 had optimal texture and the lowest cooking loss (P < 0.05). These results suggested that the ISP process (ALP) is a potential method to improve the economic value of GL.     

淡水鱼鱼糜制品加工特性及品质影响因素

文章从加工特性和机理、加工影响因素、脱腥方法三方面进行综述,总结了淡水鱼鱼糜及其制品的加工利用现状,指出了淡水鱼鱼糜加工利用中基础研究、运输条件、生产设备等不足之处。     

Some characteristics and functional properties of rapeseed protein prepared by ultrasonication, ultrafiltration and isoelectric precipitation

BACKGROUND: The presence of complex protein constituents and difficulties in extracting protein from rapeseed meal limit the application of rapeseed protein in food processing. However, double‐low rapeseed (low erucic acid, low glucosinolate) protein is a type of complete protein that is of potential use in the food industry. In this study the characteristics and functional properties of rapeseed protein prepared by ultrasonic‐assisted extraction, ultrafiltration and isoelectric precipitation were analysed and compared with those of soybean protein. RESULTS: The extraction efficiency with the ultrasonic‐assisted method was significantly higher than that obtained with the traditional method. Ultrafiltration and isoelectric precipitation yielded three different proteins: ultrafiltered protein RPs and precipitated proteins RP5.8 and RP3.6. Chromatographic separation of RPs resulted in four fractions: RPsI, RPsII, RPsIII and RPsIV. The distribution of the isoelectric point of rapeseed protein was investigated by two‐dimensional electrophoresis. The amino acid composition of RPs renders it suitable for human consumption. The hydrophobic/hydrophilic amino acid ratio of rapeseed protein was higher than that of soybean protein. The functional properties (oil adsorption ability, emulsifying capacity, foaming capacity and foam stability) of RPs, RP5.8 and RP3.6 were found to be better than those of soybean protein. CONCLUSION: Ultrasonication and ultrafiltration were significantly better than the traditional method of rapeseed protein extraction. The ultrafiltered rapeseed protein RPs had superior functional properties. The results of this study provide useful indicators for rapeseed protein as a potential replacement for other proteins. Copyright © 2011 Society of Chemical Industry     

Texture and colour properties of proteins recovered from whole gutted silver carp (Hypophthalmichthys molitrix) using isoelectric solubilisation/precipitation

BACKGROUND: According to an FAO report, carp are the cheapest and by far the most commonly consumed fish in the world. Carp have minimal growth requirements, yet rapid growth rates. Although carp are generally considered unsuitable for human consumption in the USA, they have rapidly started populating major bodies of fresh water in the USA to the extent that commercial processing becomes of interest. However, typical mechanical means of meat recovery from carp are impractical owing to the bony nature of the carp carcass. Therefore the aim of the present study was to devise processing strategies to recover fish meat from carp that could be used in the development of human food products. RESULTS: Isoelectric solubilisation/precipitation at acidic and basic pH values was applied to whole gutted silver carp. Depending on the solubilisation pH, protein and fat recovery yields were approximately 420–660 and 800–950 g kg^?1 respectively. The process effectively removed impurities such as bones, scales, skin, fins, etc. from whole gutted carp. The proteins were concentrated to approximately 900 g kg^?1, while the fat was reduced by 970–990 g kg^?1. Functional additives (potato starch, beef plasma protein, transglutaminase and polyphosphate) improved (P < 0.05) the texture of carp protein‐based gels such that it was generally comparable to the texture of Alaska pollock surimi gels. Although titanium dioxide improved (P < 0.05) the whiteness of carp gels, it was lower (P < 0.05) than the whiteness of Alaska pollock surimi gels. CONCLUSION: Isoelectric solublisation/precipitation allows protein and lipid recovery from whole gutted carp. However, if the proteins are used as a gelling ingredient in fish food products, functional additives are recommended. Copyright © 2008 Society of Chemical Industry     

抗冻剂在冷冻鱼糜生产中的应用

研究了不同抗冻剂对冷冻鱼糜性能的影响。实验结果表明,添加抗冻剂低聚糖、蔗糖、山梨醇可以有效地防止鱼糜在冷冻过程中蛋白发生变性,并能提高冷冻鱼糜的凝胶强度,混合磷酸盐能有效的提高冷冻鱼糜的保水性。通过试验得出,4种抗冻剂的优化配比是:低聚糖4%,山梨醇2%,蔗糖1%,混合磷酸盐0.3%,生产的冷冻鱼糜凝胶强度最高可达14 148.1 g/cm2。     

4种鱼糜加工漂洗液回收蛋白对罗非鱼鱼糜凝胶特性与质构的影响

目的 探究4种回收水溶性蛋白对罗非鱼鱼糜凝胶特性及质构的影响。方法 分别将等电点沉降法回收蛋白、海藻酸钠单一絮凝剂回收蛋白、壳聚糖单一絮凝剂回收蛋白和海藻酸钠-壳聚糖复合絮凝剂沉降回收蛋白以0%、5%、10%、15%、20%掺入罗非鱼鱼糜制备鱼肠,比较各样品在凝胶强度与全质构分析(texture profile analysis, TPA)参数上的差异,包括硬度、胶着性、咀嚼性、内聚性与弹性。结果 4种回收蛋白替代会对凝胶强度产生不利影响,通过等电点沉降法回收的蛋白对凝胶强度的影响最大,凝胶强度持续下降,最低达1708g·mm;以复合絮凝剂回收蛋白的掺入对原凝胶强度的影响最小,通过替代5%鱼糜,凝胶强度降为3833 g·mm。当用壳聚糖单一絮凝剂回收蛋白掺入5%时,与原鱼糜制品的TPA参数最接近,表现为硬度2505 g,胶着性1788 g,咀嚼性192.3 mJ,且内聚性和弹性也没有表现出明显差异。结论 这4种回收蛋白均以5%的添加量替代罗非鱼鱼糜时,制品凝胶强度在企业的可接受线性范围内,综合凝胶强度与TPA参数,以壳聚糖单一絮凝剂回收的蛋白替代产生的影响最小,可为回收鱼糜蛋白这一资源...     

不同蛋白添加剂对秘鲁鱿鱼鱼糜凝胶特性的影响

为了改善秘鲁鱿鱼鱼糜的凝胶特性,本文研究了添加不同种类的蛋白添加剂（卵清蛋白,猪血浆蛋白,乳清蛋白,大豆蛋白）对秘鲁鱿鱼鱼糜凝胶破断力,凹陷距离,凝胶强度,色泽的影响,并通过SDS-PAGE电泳分析其肌原纤维蛋白的降解情况。结果发现:添加卵清蛋白可显著增强鱿鱼鱼糜的破断强度和凝胶强度（p<0.05）,添加乳清蛋白和大豆蛋白对秘鲁鱿鱼鱼糜破断强度和凝胶强度的提高没有明显的促进作用,而添加猪血浆蛋白粉则对秘鲁鱿鱼鱼糜的破断强度和凝胶强度有一定的降低作用。添加各种蛋白粉的鱿鱼鱼糜凝胶凹陷度变化不大。而添加几种蛋白粉均会使鱼糜凝胶的白度降低,其中添加猪血浆蛋白粉对鱼糜白度的影响最大。通过SDS-PAGE分析,秘鲁鱿鱼鱼糜在添加蛋白后肌球蛋白的变化不明显。这表明蛋白添加剂的蛋白酶抑制剂作用效果不大。