本文選題：大豆7S蛋白 + 熱聚集行為�。� 參考：《華南理工大學(xué)》2015年博士論文

【摘要】：大豆蛋白來源豐富,營養(yǎng)價(jià)值高,在食品工業(yè)中廣泛應(yīng)用。經(jīng)過適當(dāng)修飾重組或改性可賦予大豆蛋白更好的功能特性從而拓展大豆蛋白的應(yīng)用前景。通過控制蛋白質(zhì)熱聚集行為可以得到不同類型的蛋白聚集體,用于營養(yǎng)成分和風(fēng)味物質(zhì)的輸送。目前,蛋白質(zhì)聚集行為控制及其應(yīng)用已被廣泛研究,但關(guān)于不同類型蛋白聚集體對食品結(jié)構(gòu)產(chǎn)生的差異性影響還鮮見報(bào)道。本文以大豆7S蛋白為原料,制備了兩種不同類型的聚集體:無定型聚集體和纖維化聚集體,系統(tǒng)比較了不同類型蛋白聚集體的結(jié)構(gòu)特性和消化特性,重點(diǎn)研究了以不同類型聚集體制備凝膠和泡沫性質(zhì)的差異,為拓展大豆蛋白聚集在食品領(lǐng)域的應(yīng)用提供信息和理論基礎(chǔ)。本文主要結(jié)論如下:(1)在中性(p H 7.0)和酸性(p H 2.0)條件下通過加熱分別制備大豆7S蛋白無定型聚集體和纖維化聚集體,對聚集體進(jìn)行表征。采用還原電泳(SDS-PAGE)、天然電泳(Native-PAGE)、硫磺素-T熒光(Th T)、體積排阻色譜(SEC)和原子力顯微鏡(AFM)系統(tǒng)比較了天然大豆7S蛋白、7S無定型聚集體及7S纖維化聚集體在模擬胃液消化過程中組成和結(jié)構(gòu)的變化。結(jié)果表明天然大豆7S蛋白的α和α’亞基會(huì)被優(yōu)先水解,最終產(chǎn)物富集為α、α’亞基的核心區(qū),分子量大小約為47 k Da,β亞基則不能被胃蛋白酶消化。7S無定型聚集體由于經(jīng)過熱處理,蛋白結(jié)構(gòu)展開,大量酶切位點(diǎn)的暴露使其在5 min內(nèi)迅速被酶解。7S纖維化聚集體在胃蛋白酶的作用下,首先水解成小的聚集體或者多肽,部分聚集體/多肽會(huì)通過疏水相互作用和靜電相互作用重新聚集生成短粗狀的纖維化聚集體。在蛋白分子的解離和重聚的過程中,溶液粘度明顯增加。(2)系統(tǒng)比較了大豆7S蛋白和11S蛋白在p H 2.0時(shí)的熱聚集行為,結(jié)果表明蛋白濃度越高,纖維化聚集程度越大,7S比11S更容易形成纖維化聚集體。以纖維化聚集體為原料,兩步法制備了大豆蛋白纖維化凝膠。在酸性條件下,由于纖維化聚集體表面帶有大量的電荷,分子之間互相排斥,盡管在凝膠形成的過程中加入鹽離子屏蔽部分靜電作用,但流變學(xué)和質(zhì)構(gòu)分析結(jié)果表明由大豆蛋白纖維化聚集體制備而成的凝膠強(qiáng)度較弱。在相同的預(yù)處理濃度下,11S纖維化凝膠的硬度較7S纖維化凝膠強(qiáng),但7S較11S有更好的粘性和回彈性。(3)制備了天然大豆7S蛋白、7S無定型聚集體(7SA)、7S纖維化聚集體(7SF)與低酯果膠(LMP)復(fù)合凝膠,系統(tǒng)比較了三種復(fù)合凝膠的流變學(xué)特性、質(zhì)構(gòu)性質(zhì)和形貌學(xué)特征。與7S-LMP和7SA-LMP的復(fù)合凝膠相比,7SF-LMP復(fù)合凝膠具有較高的彈性模量(G’)和粘性模量(G’’),并且具有較高的硬度、脆性和粘性。7S-LMP復(fù)合凝膠是以蛋白為連續(xù)相的凝膠網(wǎng)絡(luò)結(jié)構(gòu),LMP以非連續(xù)相形式分布于凝膠孔隙中;7SA-LMP復(fù)合凝膠是以蛋白相和多糖相穿插分布,兩相共同構(gòu)成復(fù)合凝膠的基本結(jié)構(gòu);7SF-LMP復(fù)合凝膠是以LMP為連續(xù)相,7SF以填充物形式附著于LMP凝膠網(wǎng)絡(luò)。(4)系統(tǒng)比較了天然大豆7S蛋白、7S無定型聚集體和7S纖維化聚集體的氣-水界面性質(zhì)和泡沫性質(zhì)。與天然7S蛋白和7S無定型聚集體相比,7S纖維化聚集體具有更高的起泡能力和泡沫穩(wěn)定性。蛋白的界面特性受蛋白分子結(jié)構(gòu)的影響。纖維化聚集體在形成過程中生成的小分子肽能迅速吸附到氣-水界面并鋪展,具有較強(qiáng)降低表面張力的能力。隨著界面壓(π)的增大,7S纖維化聚集體動(dòng)態(tài)膨脹粘彈模量(E)上升最快,說明蛋白分子能在界面形成緊密穩(wěn)定的蛋白質(zhì)膜,揭示了纖維化聚集體具有良好泡沫性能的原因。胃蛋白酶修飾能顯著提高7S蛋白和7S無定型聚集體的起泡性和泡沫穩(wěn)定性,對于纖維化聚集體,過度水解會(huì)導(dǎo)致蛋白質(zhì)分子之間的相互作用力減弱,泡沫穩(wěn)定性反而降低。(5)研究了7S擴(kuò)展區(qū)肽對大豆蛋白組分聚集行為的影響。采用胃蛋白酶定向水解大豆7S蛋白,得到核心區(qū)和擴(kuò)展區(qū)肽,并通過超濾的方法分離得到擴(kuò)展區(qū)肽,擴(kuò)展區(qū)肽能誘發(fā)11S聚集并有效操控11S的熱聚集行為。在熱處理過程中,蛋白結(jié)構(gòu)逐漸展開,11S和肽分子發(fā)生疏水相互作用,部分疏水基團(tuán)被重置于聚集體內(nèi)部,而親水基團(tuán)側(cè)重新排列在聚集體的表面,當(dāng)11S和水解肽的比例達(dá)到1:2時(shí),聚集體表面有足夠的親水基團(tuán),熱聚集反而受到抑制。
[Abstract]:Soy protein rich source, high nutritional value, widely used in food industry. After appropriate modification application? Function properties of recombinant or modified soy protein can give better to develop soybean protein. By controlling protein heat aggregation behavior can be obtained for different types of protein aggregates, used for transport of nutrients and flavor substances at present. Protein aggregation, behavior control and its application has been extensively studied, but the differences in the effects of different types of protein aggregates on the structure of food has not been reported. In this paper, the soybean 7S protein as raw material, two different types of aggregates were prepared: amorphous aggregates and fibrosis aggregates, a systematic comparison of the structural characteristics and digestive characteristics different types of protein aggregates, focusing on the differences in different types of aggregation preparation gel and foam properties, for the development of soybean protein Provide information and theoretical basis of applications in the field of food. The main conclusions of this paper are as follows: (1) (P H 7) in neutral and acidic conditions (P H 2) were prepared by heating soybean 7S protein amorphous aggregates and fibrosis aggregates were characterized by SDS-PAGE. Aggregates (SDS-PAGE). Natural electrophoresis (Native-PAGE), Thioflavin -T fluorescence (Th T), size exclusion chromatography (SEC) and atomic force microscopy (AFM) system compared to the natural soybean 7S protein, 7S and 7S changes of amorphous aggregates composed of aggregates fibrosis in simulated gastric digestion process and structure. The results show that the natural soybean protein 7S the alpha and alpha subunit can be hydrolyzed, the final product concentration is alpha, alpha 'core subunits, the molecular weight is about 47 K Da, beta subunit cannot be pepsin digestion of.7S amorphous aggregates after heat treatment, protein structure, a large number of Exposure restriction sites in the 5 min was quickly enzymolysis.7S fibrosis aggregates in pepsin, firstly hydrolyzed into small peptides or aggregates, part of aggregates / peptide through hydrophobic and electrostatic interactions to generate short fiber aggregation aggregates like. In the protein molecular dissociation and reunion in the process, the viscosity of the solution increased significantly. (2) a systematic comparison of the aggregation behavior of soybean 7S protein and 11S protein in P H 2 of the heat, the results showed that protein concentration is higher, the greater the degree of fibrosis aggregation, 7S is easier to form aggregates than 11S. The fibrosis fibrosis aggregates as raw material, soy protein gel fibrosis the two step method. In acidic conditions, due to fibrosis surface aggregates with a large number of charge, between the molecules repel each other, although the process in the gel formation of added salt ions part of static shielding Electricity, but the rheology and texture analysis showed that the gel strength of soy protein aggregates by weaker fibrosis was prepared. In the pretreatment of the same concentration, gel hardness is 7S 11S fibrosis fibrosis gel, but 7S 11S has better viscosity and elasticity. (3) natural soybean 7S the protein was prepared and 7S amorphous aggregates (7SA), 7S (7SF) and pectin aggregates fibrosis low ester (LMP) composite gel system, comparison of three kinds of composite gel rheological properties, texture properties and morphology characteristics. Composite gel and 7S-LMP and 7SA-LMP phase ratio, elastic modulus of 7SF-LMP composite gel high (G ') and viscous modulus (G'), and it has high hardness, brittleness and viscous.7S-LMP composite gel is a protein gel network structure for continuous phase, LMP as continuous phase distribution in the gel pores; 7SA-LMP composite gel with protein And the polysaccharide with two-phase distribution, constitute the basic structure of composite gel; 7SF-LMP composite gel is LMP as continuous phase, 7SF with filler form attached to the LMP gel network. (4) a systematic comparison of the natural soybean 7S protein, 7S amorphous aggregates and 7S fibrosis aggregates of air-water interface and foam properties properties of amorphous aggregates. Compared with natural 7S protein and 7S 7S fibrosis aggregates has higher foaming ability and foam stability. The interface characteristics of protein affected by protein molecular structure. Small molecule peptide aggregation in the fibrosis formation in rapid adsorption to the gas water interface and spreading, has a strong ability to reduce the surface tension of the interface pressure (PI). With the increase of 7S fibrosis aggregates dynamic expansion viscoelastic modulus (E) increased rapidly, that protein molecules can form stable protein membrane tightly at the interface, reveals the fiber The reason of aggregates has good foam properties. Pepsin modification can significantly improve the 7S protein and 7S foaming and foam stability of aggregates for shaping, fibrosis aggregates, excessive hydrolysis can weaken the interaction between protein molecules, the foam stability decreased. (5) studied the 7S extension effect on the aggregation behavior of peptides the soy protein group. By pepsin hydrolysis of soybean protein 7S orientation, core and extension area of peptides and extended area, peptide by ultrafiltration separation method, extension peptide can induce 11S accumulation and effective manipulation of the 11S thermal aggregation behavior. In the process of heat treatment, the protein structure gradually expanded, and the peptide 11S hydrophobic interaction, hydrophobic part is reset on the aggregates, and the hydrophilic group side rearranged on the surface of the aggregates, while 11S and hydrolyzed peptide when the ratio reached 1:2, There is enough hydrophilic group on the surface of the aggregate, and the heat accumulation is restrained.

【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TS201.21

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本文編號(hào)：1766487