低酚棉籽蛋白质酶水解过程苦味形成和脱除的研究

低酚棉籽的贮存蛋白和非贮存蛋白分别以胃蛋白酶、菠萝蛋白酶和1．398枯草杆菌中性蛋白酶进行水解,实验结果表明:只有胃蛋白酶水解贮存蛋白时才会产生明显苦味;所产生的苦味的强度与水解率有关,水解率小于0．4%时感觉不到苦味,随着水解率的增大,苦味开始形成和增大,之后又趋下降。对有苦味的水解液用粉末状活性炭处理可以有效地降低苦味,且蛋白质的损失小于4%。     

酶法制作低酚棉籽蛋白发泡粉的研究

本论文对以脱脂低酚棉籽仁粉为原料,经蛋白质提取及蛋白酶水解制作植物蛋白发泡粉进行了研究．通过实验比较了不同酶种以及蛋白质底物浓度、用酶量和酶反应时间等条件对水解液发泡性能的影响,并测定水解过程中水解率随反应时间的变化。确定了较佳的酶种和反应条件。讨论了蛋白质水解率与发泡性能的关系．成品发泡粉发泡能力强,风味优良。     

三相萃取法提取棉籽脱酚蛋白的质量分析及安全监控

利用三相萃取法制备棉籽脱酚蛋白,测定其中游离棉酚、蛋白质与纤维含量,以确定棉籽脱酚蛋白质量.并对主要影响因素--游离棉酚含量进行了安全监控:用紫外分光光度法测定其中游离棉酚的含量,用苯胺显色来检测游离棉酚的含量.结果表明,该方法具有简便、重现性好等优点,可作为棉籽脱酚蛋白的安全监控方法.     

棉籽多肽的制备工艺优化及功能特性

为有效利用棉籽这一优质蛋白质资源,以棉籽蛋白水解度(DH)和水解液感官(色泽,气、滋味)为评价指标,对蛋白酶进行选择,再以棉籽蛋白DH为指标,利用单因素实验及响应面实验对复合蛋白酶水解棉籽蛋白制备棉籽多肽的工艺条件进行优化,并研究了棉籽多肽的氨基酸组成及功能特性。结果表明：选择碱性蛋白酶和风味蛋白酶按质量比2∶1构成复合蛋白酶;最优工艺条件为水解pH 10、水解温度60℃、加酶量6 000 U/g、水解时间90 min,在此条件下棉籽蛋白DH为29.35%;棉籽多肽中有7种必需氨基酸,必需氨基酸总含量达到12.50 mg/100 mg,占氨基酸总量的26.25%;与棉籽蛋白相比,棉籽多肽的吸湿性有较大提升;在20℃时棉籽多肽的吸油性较好;在弱碱性时棉籽多肽的乳化性与乳化稳定性较好;棉籽蛋白DH与棉籽多肽的起泡性呈正相关,与泡沫稳定性呈负相关。采用该工艺制备的棉籽多肽氨基酸含量丰富,具有良好的功能特性。     

棉籽蛋白资源开发研究进展

我国棉花资源丰富,棉花加工的副产物——棉籽经脱壳提油后的棉籽粕中蛋白质含量高达40%~50%。棉籽蛋白是一种营养价值高、品质良好的植物蛋白资源。介绍了棉籽蛋白的营养价值以及脱酚棉籽蛋白粉、棉籽浓缩蛋白、棉籽分离蛋白等产品的制备工艺及产品的溶解性、持水性、持油性、乳化性与乳化稳定性、起泡性与泡沫稳定性等功能特性的研究进展,并对棉籽蛋白产品目前在食品、饲料、发酵等领域的应用情况进行了论述。     

大豆分离蛋白乳化性的研究

采用蛋白质乳化容量电导法,对不同浓度、ＰＨ和酶水解条件下大豆分离蛋白乳化容量和乳化稳定性进行测定,结果表明：大豆蛋白的乳化性在低密度时随浓度上升而增加,浓度达到６％以后趋于稳定;等电点时（ＰＨ４．５）,乳化性最差,偏离等电点后尤其在偏碱性条件下,乳化性明显增加,酶水解后,乳化性变化产大,水解度１７％时,乳化性最佳。     

胰蛋白酶限制性水解脱酚棉籽蛋白的研究

采用胰蛋白酶对脱酚棉籽蛋白进行限制性酶解,以改善棉籽蛋白在中性条件下的溶解性.以酶解棉籽蛋白水解度和溶解度为指标,对胰蛋白酶水解脱酚棉籽蛋白的条件进行了优化.结果表明,胰蛋白酶水解脱酚棉籽蛋白的优化条件为:酶底比2∶ 1(50 000 U/g),底物质量浓度100 g/L,pH 10,于20 ℃下酶解3 h.在此条件下,酶解棉籽蛋白的水解度为10.87%,溶解度为63.48%.与酶解前相比,溶解度提高了43.82%.溶解度分析结果表明,限制性酶解棉籽蛋白在pH 1～11范围内均具有较好的溶解度,仍然保持了棉籽蛋白酸溶性的特点.     

棉籽胚液-液-固三相萃取法脱酚的试验研究

棉籽蛋白是蛋白质含量最高的植物蛋白,由于棉酚的存在使其利用率大大受到限制。采取液-液-固三相萃取法脱酚工艺可以有效地脱出棉籽胚中的棉酚,还可以保证棉籽蛋白的低变性,具有脱毒效果好,能耗低,棉酚可回收等特点。     

脱酚棉籽粕蛋白起泡性的研究

以醇法脱脂脱酚棉籽粕为原料,用碱性蛋白酶进行水解,制得酶解脱酚棉籽粕蛋白,分别对酶解前后棉籽粕蛋白的起泡能力(FA)和起泡稳定性(FS)进行单因素实验,并通过正交实验对酶解前后棉籽粕蛋白的FA进行了比较。结果表明,在水解度为19.91%的情况下,酶解后棉籽粕蛋白的FA较酶解前的棉籽粕蛋白有显著性的提高。匀浆速度对酶解后棉籽粕蛋白的FA具有显著性的影响。     

“碱溶酸沉法”不适于脱脂棉粕分离蛋白的提取

为了测定棉籽蛋白的营养价,并进行动物慢性毒性试验,山东省粮油科研所于1983年开始,进行了利用脱脂棉粕提取分离蛋白的试验。试验发现,由脱脂棉粕提取分离蛋白,即不宜采用“碱溶酸沉法”从脱脂棉粕中提取分离蛋白。现将试验情况介绍如下,供有关方面借鉴。 (一)预榨浸出棉粕碱溶性蛋白含量低,有效赖氨酸严重受破坏 据有关资料介绍,棉籽蛋白的营养价值,与棉籽蛋白中的“棉酚蛋白质复合物”的增加以及赖氨酸有效性的降低有关。因为一旦棉酚和棉籽蛋白结合(结合棉酚从0增加至3.25％),那么蛋白质在0.02N浓度     

无腺体棉籽蛋白化学改性研究

通过时无腺体棉籽蛋白进行化学改性，使棉籽蛋白的功能特性得到了较大的改善，特别表现在持水性、持油性、乳化性及乳化稳定性、凝胶组织等方面。     

Molecular Structure and Functionalities of Protein Isolates Prepared from Defatted Cottonseed Flour Succinylated at Various Levels

Protein isolates were prepared from glandless cottonseed flour succinylated at various levels. Succinylation levels of the resultant proteins followed first order kinetics with respect to succinic anhydride concentration added. Succinylation decreased the amount of free sulfhydryl, as well as ξ-amino groups of proteins, but did not change intermolecular disulfide bonds. Protein isolate prepared from highly succinylated flour consisted of one homogeneous protein agglomerate, while isolate from unmodified flour contained several heterogeneous proteins. Water solubility of the isolates increased logarithmically with respect to degree of succinylation, with the sharpest increase at 95% succinylation or higher. Heat coagulability had an inverse-linear relationship with amounts of negative charges on protein molecules. Emulsion capacity and oil absorption capacity were not significantly changed at less than 60% succinylation. However, these increased markedly at greater than 60% succinylation. Emulsion capacity had a positive, but not linear correlation with water solubility of proteins.     

Some functional properties of oilseed proteins

Oilseeds have potential food uses because of their high protein content. Besides, these proteins when added to a type of foods, supply desirable functional properties, such as whipping capacity and viscosity, emulsification and water and oil holding capacities. Rapeseed and soybean protein isolates were found to possess whipping capacity followed by those of sunflower, peanut, sesame, cottonseed and safflower. The addition of sugar improved the whipping properties of oilseed proteins. The whipping capacity of oilseed proteins decreased due to heating at 100 degrees C for time of 15 to 60 min. Soybean protein had the highest emulsifying capacity compared with the other oilseed proteins. The heated oilseed proteins had emulsification properties similar to or better than the control. Glandless cottonseed protein had high water and oil holding capacities. The water holding capacity of oilseed proteins decreased gradually as the duration of heating at 100 degrees C was increased. On the other hand the heated oilseed proteins had oil holding capacities similar to or better than unheated proteins.     

棉籽分离蛋白功能性质的研究

考察了棉籽各分离蛋白,包括清蛋白、球蛋白、醇溶谷蛋白及谷蛋白在棉籽蛋白中所占的比例,研究了各蛋白的功能性质,包括吸水性、吸油性、乳化性和乳化稳定性、起泡性与泡沫稳定性以及各蛋白的抗氧化活性。结果表明,谷蛋白为棉籽蛋白中的主要分离蛋白,棉籽清蛋白具有较高的吸水性、乳化性、乳化稳定性以及起泡性,吸油性相对较差,适用性相对较好,但在棉籽蛋白中含量较少,而谷蛋白的吸水性、乳化性、起泡性很差,具有一定的吸油性,适用性较差,但在棉籽蛋白中含量丰富,在抗氧化活性方面,各分离蛋白的抗氧化活性能力都较差,需要进行改性处理。     

Foaming properties of oilseed proteins

Oilseeds are important sources of edible proteins. Their varieties varied in oil and protein content; sesame and rapeseeds had the highest oil content, but soybean and glandless cottonseeds had the highest protein content. Foaming properties of oilseed proteins are important for the domestic market to be used in the preparation of various food products. Whole rapeseed had the highest foam capacity followed by soybean, sunflower, safflower, glandless cottonseed, peanut and finally sesame. The extraction of lipids from oilseeds caused a significant improvement in their foam capacity and foam stability. High positive correlation was found between soluble proteins and foam capacity of oilseeds. The foam capacity was high at pH 7, and decreased below it reaching a minimum at pH 4. The foam stability also varied with pH; being maximum at the isoelectric point and minimum at pH 7. The foam capacity of oilseed protein isolates decreased with the prolongation of heating time at 100 °C.     

微波辅助酶解棉籽粕的条件优化及酶解产物功能性质研究

研究了微波辅助碱性蛋白酶和风味蛋白酶双酶酶解棉籽粕的工艺条件.通过单因素实验确定了碱性蛋白酶酶解的最佳工艺条件为:微波温度60℃,微波功率500 W,酶加量5％(以底物质量计),酶解时间15 min;风味蛋白酶酶解的最佳工艺条件为:微波温度60℃,微波功率600W,酶加量5％(以底物质量计),酶解时间15 min.参照单因素优化条件,对棉籽粕进行连续酶解,酶解液多肽含量为13.32 mg/mL.棉籽粕经过微波连续双酶酶解后,吸油性、起泡性、乳化性等功能性质得到改善.     

碱性蛋白酶限制性酶解对蓝圆鲹分离蛋白功能特性的影响

以蓝圆鲹(Decapterus maruadsi)分离蛋白为原料,采用碱性蛋白酶对其进行限制性酶解,研究水解度(degree of hydrolysis,DH)对分离蛋白酶解产物溶解性、持油力、乳化性与起泡性等功能特性的影响.结果表明,碱性蛋白酶酶解产物的相对分子质量显著下降.酶解可有效提高分离蛋白的溶解性,其溶解度随...     

Enhancement of Frying Oil Stability by a Natural Antioxidative Ingredient in the Coating System of Fried Meat Nuggets

Cottonseed oil containing commercial antioxidants was used for continuous (a 2-day time period; < 24 hr) frying of beef nuggets that were batter-breaded with either 100% commercial coating mix or a coating system containing defatted glandless cottonseed flour (GCF). Analyses of oil samples revealed that oil used for frying the nuggets with the GCF-containing coating was less susceptible to lipid hydrolysis and oxidation and color-darkening. GCF in the coating also minimized lipid oxidation in beef nuggets fried in the oil at various stages of heating time during the 2-day frying operation. Results indicated that GCF in the coating not only could enhance the oxidative stability of fried nuggets but also could decrease the breakdown of the frying oil.     

新的食品基质——无腺体棉籽磷脂

通过对无腺体棉籽磷脂的结构、组成、性质的叙述，并与大豆磷脂进行比较，得出结论：棉籽磷脂性质比大豆磷脂性质更优越，可作为一种新的食品基质。     

Effect of Partial Proteolysis and Succinylation on Functionality of Corn Germ Protein Isolate

Corn germ protein isolate (CGPI) was partially hydrolyzed with trypsin and pepsin and succinylated at three levels. Various functional and electrophoretic properties of the native and modified protein were determined. Water absorption and foaming properties of CGPI were Improved by partial hydrolysis with trypsin; emulsifying capacity and nitrogen solubility were reduced; oil absorption was increased only slightly. CGPI pepsin hydrolyzate has decreased oil absorption, nitrogen solubility and emulsifying capacity but improved foaming properties; water absorption was unchanged. Treatment of CGPI with succinic anhydride improved water and oil absorption, nitrogen solubility and foaming capacity but decreased emulsifying capacity; foam stability was unchanged. Succinylation retarded electropohoretic mobility while hydrolysis altered band intensities.