【作者】 蒋连平；

【导师】 姜绍通；

【作者基本信息】 合肥工业大学 ， 农产品加工及贮藏工程， 2007， 硕士

【摘要】 菜籽饼粕是菜籽榨油过程中产生的一种副产物，是经压榨脱脂后形成的，其粗蛋白含量一般为35～45％，为全价优质的植物蛋白，可用作各种食品添加剂，其酶解产物还可获得功能性多肽。国内在菜籽饼粕产品方面的开发程度低，多用于动物饲料和肥料，从而造成资源浪费。因此对菜籽饼粕的升值加工是一项重要的应用研究工作。本文主要研究了以高温双低菜籽饼粕为原料，采用碱提酸沉结合超滤浓缩制备菜籽分离蛋白的工艺，优化了各自反应过程的工艺条件，对产品干燥工艺及产品性质进行了研究，并建立了碱性蛋白酶有限水解产品的动力学方程。试验研究的主要结论如下：（1）以蛋白提取率为指标，结合单因素试验及正交试验对蛋白提取工艺进行优化，确定了最佳工艺参数组合：pH=13，提取次数为3次，料液比分别为1∶10、1∶8和1∶6，温度40℃，每次提取40min。蛋白提取率为61.9％。（2）酸沉和超滤浓缩工艺的最优工艺条件为：调节提取液pH4.5进行沉淀，上清液在温度40℃、流速2m/s和压力O.10Mpa条件下进行超滤浓缩。蛋白一次沉淀率达到63.2％。超滤过程中，蛋白截留率达到68.5％，经中型膜放大试验发现蛋白截留率仍然达到67％左右。污染后的膜经清洗，恢复系数达到90％以上。（3）控制干燥机进口温度180℃，出口温度80℃，将沉降蛋白和超滤液混合均质后经离心喷雾干燥得到淡黄色粉末状的菜籽分离蛋白产品，其蛋白含量为70.5％，蛋白最终得率为54.7％。对产品及低温粕得到的分离蛋白中的氨基酸进行分析对比，发现两者的氨基酸成分及含量基本相当。（4）通过测定产品的吸水性、起泡性、乳化性和乳化稳定性并与大豆蛋白对比分析后得出：喷雾干燥得到的产品其吸水性远不如大豆分离蛋白，起泡性明显好于大豆分离蛋白，乳化性和乳化稳定性与大豆蛋白相当。（5）以菜籽分离蛋白为底物，选取碱性蛋白酶对其进行酶解。碱性蛋白酶在温度55℃，pH9.0，底物浓度为4.32g/100ml，酶浓度0.50g/100ml的酶解条件下，水解能力最佳。菜籽蛋白的水解度随酶浓度的增加而增加，随底物浓度的增加而下降。在大量实验的基础上得到碱性蛋白酶在pH 9.0和温度55℃条件下有限水解菜籽分离蛋白的动力学方程：χ＝4.292 ln[1+（（143.346₀）/S₀-6.058）t]，当水解度≤40％（x≤40）时，该方程经验证可以用来指导和优化酶解反应进程。（6）在最高水解度条件下，碱性蛋白酶活力随着水解时间的延长而逐渐降低。当酶解反应至120min时，酶活力降为原来的36％。碱性蛋白酶水解菜籽蛋白在水解时间段为30～60min时，菜籽肽的苦味评价值最高。更多还原

【Abstract】 Rapeseed meal is a by-product of oil extraction ,which is formed after the squeezing and defatting process.The content of total protein reaches 35%-45% and can be exploited as food additive because of its good quality.Bioactive peptides can be obtained from protein hydrolysate. However, the meal hasn’t been utilized completely.It is only used for animal feed and fertilizer ,thus leading to the waste of resources. Therefore,it’s significant to work on the value-added process of rapeseed meal.On the basis of alkali-extraction and acid-precipitation combining with ultra-filtration, the preparation of rapeseed protein isolate(RPI) from high-temperature double-low meal was studied and the respective reaction conditions were optimized. Then the product’s drying conditions and central properties were investigated. A kinetic model equation simulating the enzymatic hydrolysis with alkaline protease was obtained.The main conclusions of the experiments were as follows:(l)With the extraction rate of protein as the index and through the optimization of single factor and orthogonal experiments,the optimum conditions of the protein extraction were: pH =13, 3 times extraction,the ratio of material and solution(g/ml) were 1:10,1:8,1:6 respectively ,the temperature was 40℃and the time of extraction was 40 minutes.The extraction rate of protein was 61.9%.(2)The optimum technical conditions of acid-precipitation and ultra-filtration process were: precipitation of protein at pH4.5.For the ultra-filtration of the separated solution, the temperature was 40℃,the velocity of flow was 2m/s, the pressure was 0.10Mpa.The precipitation rate of protein was 63.2% . In the ultra-filtration process ,the capture rate of protein was 68.5% and it still retain 67% after enlargement test.The volume flow of solution through membrane recover 90% of original by washing.(3)The intake and exit temperature of the spray dryer were 180℃and 80℃respectively.Through centrifugal spray drying to the homogenized protein solution,the flaxen RPI powder was obtained and the content of protein was 70.5%.The final recovery rate of protein was 54.7%. Compared with the product from low-temperature meal, the RPI has the similar amino acid composition.(4)Water binding capacity,foaming capacity,emulsification capacity and stability of RPI were studied.Compared with the soybean protein isolate(SPI), the foaming capacity of RPI is better and its emulsification capacity and stability are equivalent to SPI, but its water binding capacity is worse.(5)The substrate RPI was hydrolyzed by alkaline protease and the degree of hydrolysis(DH) was best under the hydrolysis condition as follows: temperature was 55℃, pH=9.0, concentration of substrate and enzyme were 4.32g/100ml and 0.50g/100ml respectively. The DH ascended as the increase of enzyme concentration and descended as the increase of substrate concentration. Under the condition of pH9.0 and 40℃, a kinetic model equation simulating the enzymatic hydrolysis of RPI was obtained on the basis ofmany experiments: The equation can be used to instruct andoptimize the hydrolysis process when the DH≤40%.(6)Under the best condition of high DH, the activity of alkaline protease reduced gradually in the hydrolysis process and the enzyme activity reduced to 36% of original after 120min.The evaluation of bitterness produced by the peptides was best between 30min to 60min.更多还原