【作者】 何东平；

【导师】 张声华；

【作者基本信息】 华中农业大学 ， 农产品贮藏与加工， 2006， 博士

【摘要】 花生是我国主要的油料作物之一，制油是花生的主要用途，而制油后的花生饼一般都作为饲料，花生蛋白资源没有得到充分利用，通过酶解可以大大提高其营养价值和商业价值。本研究主要探讨水相酶法同步提取冷榨花生饼中蛋白质和花生油的新技术、花生冷榨过程特征、产物的理化品质、花生多肽的制备分离与分析、以及花生超细粉工艺与品质评价的研究等，为开发利用花生、冷榨花生饼提出了新途径。主要研究内容及结果如下：1水相酶法同步提取冷榨花生饼中蛋白质和花生油1．1花生冷榨过程与基本特性研究以花生油料为研究对象，探讨分析了植物油料在冷态压榨过程中的基本特性及变化规律、冷态压榨下整粒花生仁和碎粒花生仁的出油压力与出油应变、出油率、应力-应变关系、实际压缩比等问题。建立了花生油料出油率与压榨压力的经验公式、应力-应变经验公式和实际压缩比理论计算模型。1．2水相酶法处理冷榨花生饼水相酶法处理冷榨花生饼同步提取花生蛋白和花生油，即在水介质中碾磨花生冷榨饼，调整分散体系的pH值，用中性蛋白酶酶解，经离心分离后得到乳油和蛋白质水解产物，乳油经过破乳得到花生油。以pH、酶解温度、酶解时间、加酶量为单因素进行了单因素酶解研究，再以水解度为响应值对酶解条件进行响应面分析，得到最佳工艺条件为：pH6.7、反应温度50℃、酶解时间2.5 h、加酶量为6500u／g底物。冷榨花生饼出饼温度≤60℃，残油6.83％，冷榨花生饼中蛋白质含量≥55％，通过水相酶法最终产品花生蛋白质水解物纯度为89.94％，花生蛋白质得率为48.85％。1．3水相酶法提取的蛋白质产物的理化特性相同条件下，花生水解蛋白的乳化性、乳化稳定性、起泡性、吸油性和持水性和花生碱提蛋白相比都有所改善。提升幅度乳化性高达11.1％、乳化稳定性37.3％、起泡性34.0％、吸油性0.039(g／g)及持水性1.324(g／g)，更适合于肉制品和乳制品等食品加工中。花生水解蛋白比花生碱提蛋白泡沫的稳定性稍差些，下降了4.6％。这可能是因为酶解作用，使水解蛋白的粘度较低，液膜强度小，从而使泡沫稳定性下降。1．4水酶法提取的花生油品质分析通过比较分析水酶法提取的花生油和水代法提取的花生油的理化性质和脂肪酸组成，水相酶法提取的花生油与现代的水代法和机榨法生产的花生油相比，它们之间没有多大区别，均符合国家花生油标准GB 1534-2003；其中按水相酶法提取的花生油，产品质量好，出油率高，按其加工工艺和方法生产的花生油避免了与有机溶剂的接触，不存在花生油中残留溶剂的问题，确保花生油的食用安全性。2花生多肽的制备及纯化用AS1.398中性蛋白酶酶法水解花生蛋白制备营养性花生多肽。本研究对影响花生蛋白水解得花生多肽的各种影响因素，如酶制剂的筛选，酶解工艺参数等进行了系统研究。通过正交实验，得到最佳工艺参数是pH值7.0、温度42℃、加酶量6500U／g原料、酶水解时间8h、料液比1：8(w／v)。用AS1.398蛋白酶水解得到花生肽粗品，运用超滤装置中5KD中空纤维膜组件截取分子量范围5KD以下的组分、用葡聚糖凝胶层析分离得到2个活性峰，经含尿素的SDS-PAGE凝胶电泳显示为单一的谱带，分子量范围在6.5KD和2KD左右。再通过3KD中空纤维膜组件截取样品分子量范围3KD以下的组分，经过用葡聚糖凝胶层析和SDS-PAGE凝胶电泳分析得到1个活性峰，分子量在2KD左右。运用柱前衍生技术对多肽进行了氨基酸组成分析，借以了解多肽的一级结构，为深入结构分析和功能研究奠定基础。3花生超细粉生产工艺及其性质的研究食用冷榨花生饼经超细粉碎加工生产的花生超细粉由于粒度小、白度白、糊化性能良好，其食品加工性质发生了很大的变化。花生粗粉主要以大于100目的颗粒存在，颗粒粗于标准面粉(120目)，花生超细粉则比标准面粉细(小于140目)。花生超细粉由于粒度细，摩擦角大(56.7°)，流动性变差。花生超细粉糊化温度降低，糊化完全，回生慢，因此，花生超细粉能替代面粉制作各种食品。更多还原

【Abstract】 Peanut is one of the main oilseed-crops in China. For by-product after extract peanutoil, peanut cake was used as feeds, but its value for resources hasn’t been fully utilized inthe past. The protein and oil in cold press peanut cake is main components. A treatingtechnique, enzymatic hydrolysis method, is developed and used to isolate peanut proteinand oil from cold press peanut cake at the same time. All the basic characteristics in thecourse of peanut cold-pressing, physical and chemical properties of product, preparationand purification of polypeptides, the processing technology and properties of peanutsuperfine powder were studied, results are as follows:1. Study on synchronous extracting peanut protein and peanut oilfrom cold pressed peanut cake by aqueous enzymatic hydrolysis1.1 Study on the basic characteristics of cold-pressing process of peanutDuring the processes of cold pressing on the whole peanut kernels and the brokenones, many relative factors, such as oil yielding pressure, oil yielding strain, and oilyielding efficiency, stress-strain relations and actual compress ratio, etc., were studied.Two empirical formulas were set up to express the relations between oil yieldingefficiency and pressure, stress and strain etc. And the theoretical model for calculatingactual compress ratio has also been brought forward.1.2 Synchronous extraction of protein and peanut oil from cold-pressedpeanut cakes by aqueous enzymatic hydrolysisIn this study, the aqueous enzymatic technique was applied to obtain both the peanut protein and the peanut oil from cold pressed cake at the same time. The cold-pressedpeanut cake was ground with water to get a peanut mash. Adjusted the pH value of thedispersed phase, it was hydrolyzed enzymatically by neutral protease and isolated bycentrifugation, emulsified oil and protein were obtained. Then emulsified oil was furtherseparated through demulsification and got peanut oil. The enzymatic hydrolysis test assingle factor, i.e, pH, temperature, duration time and applied amount of protease, wasconducted. To obtain the optimum conditions of the hydrolysis with neutral protease, amethod as response value by hydrolysis degree was adopted to conduct response surfaceanalysis. The results showed that optimum conditions were as follows: applied weight ofenzyme, 6500u/g, hydrolysis time,2.5 h, temperature, 50℃and pH, 6.7. Theproduction temperature of cold-pressed peanut cake is≤60℃, with the product of≥55% protein content and 0.27% residual oil content.And the purityof protein hydrolysateis 89.94%, and the result rate of protein, 48.85%.1.3 Study on the physical and chemical properties of peanut proteinhydrolysatesFunctional properties of peanut protein hydrolysates and alkaline extracted proteinhave been studied in this paper. The functional properties of peanut protein hydrolysatehas improved dramatically compare with the alkaline extracted protein, its emulsifyingability increased by 11.1%; emulsive stability,by 37.3 %; water-holding capacity, by34.0%; oil sorption , by 0.039(g/g) and foaming ability , by1.324(g/g), therefore, peanutprotein hydrolysate is very suited to the needs of meat products and dairy processing.But foaming stability of peanut protein hydrolysates is slightly weaker than one ofalkaline extracted protein and dropped by 4.6%. This is probably that the low viscosity ofpeanut protein hydrolysates reduced the intensity of liquid membrane, so that the foamingstability of peanut protein hydrolysate was down.1.4 Analysis of properties of peanut oil extracted by aqueous enzymaticmethod By comparing and the components of fatty acid and it’s the physical and chemicalproperties, it is found that the peanut oil made by aqueous enzymatic is almost the samewith ones by aqueous extraction peanut oil and/or cold-pressed peanut oil. The qualitiesof these products measure up to the national standards GB 1534-2003. The quality ofpeanut oil is better, and the oil yielding efficiency. This method could avoid theassociation with other organic solvents, to guarantee the edible security of peanut oil.2. Preparation and purification of peanut polypeptidesIn this study, neutral protease AS1.398 was used to enzymatically hydrolyze peanutprotein to produce polypeptides. The choice of factors, such as enzyme preparations andthe process parameters were studied as a systimaematic works. The optimum extractingcondition was attained by orthogonal experiments,i.e., pH, 7.0; temperature, 42℃;dosage of enzyme action (enzyme/substrate), 6500u/g;treatment time, 8h and ratio ofraw material to solvent, 1:8 (w/v).Polypeptide was extracted from peanut peptides and then isolated by ultrafiltration with5kd of hollow fiber to collect fractions (≤5kd), and then 2 active peaks were obtained byglucan gel chromatographic. The purity of them were identified by urea-containingSDS-PAGE gel electrophoresis, molecular weights were 6.5KD and 2KD respectively.Use the ultrafiltration to collect fractions(≤3kd), 1 active peaks were obtained byglucan gel chromatographic, molecular weights was 2KD.In order to understand the primary structure of polypeptides, technique of pre-columnderivatization was used for amino acids analysis.3. Properties of peanut superfine powder and its processingtechnologyPeanut superfine powder from cold-pressed peanut cake have more changes inproperties due to their granules were fine, therefore Peanut superfine powders have goodwhiteness and pasting property. The granules of peanut raw powder are mostly existedmore than 100 meshes, at same time, these granules are also greater than the standard flour (120 meshes), while peanut superfine powder (＜140 meshes) is smaller than thelatter. Due to friction angle(56.7°) of superfine powder is great therefore peanutsuperfine powder is poor in mobility,. Analysis of the pasting property of peanutsuperfine powder shows that the gelatinizing temperature is lower than common peanutpowder, with complete gelatinization and slow retragradation. So peanut superfinepowder from cold-pressed peanut cake can be used to replace wheat flour to preparevarious foods.更多还原