高乳化性大豆蛋白的制備及其界面流變性質(zhì)的研究
發(fā)布時間：2019-05-16 04:44
【摘要】：大豆蛋白是一種產(chǎn)量大、價格低廉的植物蛋白資源。過去的幾十年,針對大豆蛋白結(jié)構(gòu)改造提高功能性質(zhì)的研究很多,有大量研究集中在如何提高其加工功能性質(zhì),如乳化性、起泡性、凝膠性等等,也取得了很多進展。然而迄今為止,結(jié)構(gòu)改造后大豆蛋白改性產(chǎn)品的加工功能性質(zhì)例如乳化性等性質(zhì)固然比大豆分離蛋白或者濃縮蛋白性質(zhì)有顯著提升,但尚未有具有很高商業(yè)價值的、可與酪蛋白酸鈉等大分子乳化劑相媲美的高乳化性大豆蛋白產(chǎn)品。本論文利用酶水解和糖基化修飾等方法,對大豆蛋白進行結(jié)構(gòu)改性,旨在研究和開發(fā)出一種高乳化性大豆蛋白。同時,基于對不同結(jié)構(gòu)大豆蛋白界面流變性質(zhì)的研究,進一步闡明具有良好乳化性的大分子乳化劑在油水兩相界面的作用機制以及所需要的結(jié)構(gòu)特征,為更好地開發(fā)和應(yīng)用大豆蛋白作為表面活性物質(zhì)和膠體穩(wěn)定劑提供理論依據(jù)和指導(dǎo)。首先研究了限制性酶水解和糖基化法的組合應(yīng)用對大豆蛋白乳化性質(zhì)和界面性質(zhì)的影響。研究發(fā)現(xiàn),大豆蛋白水解產(chǎn)物中對乳化性質(zhì)最有利的主要是大分子量部分(Mw30 k Da),小分子量的大豆肽乳化性質(zhì)較差。肽的糖基化反應(yīng)結(jié)果顯示,隨著糖分子質(zhì)量的增加,糖基化大豆肽的乳化穩(wěn)定性逐漸增加。糖的結(jié)合可以降低大豆肽的表面疏水性和凈電荷,減少肽鏈間的排斥作用,增加界面吸附量。表面活性測定發(fā)現(xiàn)大豆肽-葡聚糖共聚物在界面上緊密排列,并且每個分子占據(jù)很小的面積。激光共聚焦顯微鏡觀察發(fā)現(xiàn)大豆肽-葡聚糖共聚物可以在油滴表面形成厚的吸附層。界面流變測試說明大豆肽可以在界面形成具有高粘彈性和較寬線性粘彈區(qū)的界面膜,且大豆肽與葡聚糖共聚物可以在界面上形成多層吸附。研究結(jié)果表明了大豆肽-葡聚糖共聚物具有較好的表面性質(zhì),可以在界面上緊密排列并形成一定厚度的界面膜,包裹油滴,提高乳化體系的穩(wěn)定性。在此基礎(chǔ)上,基于保留大豆水解物中大分子量部分的目的,研究了選擇性酶解方式(只水解大豆蛋白11S部分,保留7S部分)對大豆蛋白乳化性質(zhì)和界面性質(zhì)的影響。以SPI有限水解、選擇性水解11S、7S以及SPI為原料,研究了不同結(jié)構(gòu)的蛋白的界面性質(zhì)和穩(wěn)定乳狀液的機制。研究發(fā)現(xiàn),選擇性酶解11S后大豆蛋白的乳化性質(zhì)顯著提高,可與7S蛋白以及酪蛋白酸鈉相媲美。蛋白質(zhì)穩(wěn)定乳狀液可以通過兩種方式:一種是結(jié)構(gòu)靈活,呈棒狀結(jié)構(gòu)的蛋白(如酪蛋白酸鈉),盡管其界面模量低,但是蛋白可以沿軸向垂直于界面的方向進行吸附,界面吸附量大,排列緊密,通過形成厚的界面膜來穩(wěn)定乳狀液;另一種是分子量較小的球狀蛋白(如7S),可以在界面上形成高粘彈性的界面膜,以此來保護油滴不發(fā)生絮凝和凝結(jié)現(xiàn)象。RG既具有球狀結(jié)構(gòu)(7S),又包含結(jié)構(gòu)靈活的水解肽,因此形成的界面膜兼具模量高和界面吸附量大兩個優(yōu)點,可以形成穩(wěn)定的乳狀液。為了考察上述研究中具有良好乳化能力的7S和RG蛋白是否具有進一步提升乳化能力的可能,論文研究了以共價鍵和非共價鍵結(jié)合葡聚糖,對7S和RG蛋白乳化性質(zhì)的影響。結(jié)果發(fā)現(xiàn),不管是否與葡聚糖以共價鍵結(jié)合,RG的粒徑均增大,表面凈電荷量減少,制備的乳狀液粒徑較小,但是在酸性和高鹽離子濃度條件下乳狀液穩(wěn)定性比酪蛋白酸鈉稍差。可能因為RG蛋白中的小分子量肽部分的存在不利于乳狀液的穩(wěn)定性。由7S制備的乳狀液,不管是否以共價鍵與葡聚糖結(jié)合,在酸性條件下,穩(wěn)定性都顯著優(yōu)于酪蛋白酸鈉;在高鹽離子濃度的條件下,酪蛋白酸鈉制備的乳狀液具有較好的穩(wěn)定性,7S與葡聚糖的糖基化產(chǎn)物制備的乳狀液穩(wěn)定性僅次于酪蛋白酸鈉。為了進一步提高7S在等電點處的穩(wěn)定性,選擇了同樣具有表面活性的兩種陰離子多糖,可溶性大豆多糖(SSPS)和阿拉伯膠(GA),分別與7S進行靜電復(fù)合,同時研究兩種多糖對7S在氣-水界面和油-水界面流變性質(zhì)的影響。結(jié)果發(fā)現(xiàn),兩種多糖對7S在兩種界面的吸附影響完全不同。對于7S-SSPS,在氣-水界面,復(fù)合物的吸附行為由7S主導(dǎo),吸附速率比單獨的7S慢。相反的,在油-水界面,復(fù)合物的吸附行為一開始由SSPS主導(dǎo),之后變?yōu)?S主導(dǎo)。乳狀液穩(wěn)定性測定表明7S-SSPS形成的乳狀液完全不受p H影響,即使在7S等電點附近也具有很好的穩(wěn)定性。可能是因為與7S結(jié)合的SSPS緊密纏繞在7S周圍,通過空間位阻效應(yīng)起到穩(wěn)定乳狀液的作用。GA的加入并沒有改善7S乳狀液在等電點附近的穩(wěn)定性,主要是因為界面吸附行為由GA主導(dǎo),而GA形成的乳狀液同樣受p H影響很大。令人意外的是,不管有無多糖的存在,7S在任意p H條件下均能形成具有高粘彈性模量的界面膜,說明等電點處乳狀液的分層現(xiàn)象主要是液滴間的靜電相互作用導(dǎo)致的,而與界面膜的機械強度無關(guān)。論文最終對具有高乳化能力的7S和RG在粉末油脂體系的應(yīng)用效果進行了初探。以氫化椰子油為芯材,RG蛋白為乳化劑,在蛋白含量達到6%或者高于6%時,不論是噴霧干燥前形成的乳狀液、噴霧干燥后制備的粉末油脂還是粉末油脂復(fù)水后形成的乳狀液都具備粒徑小、分布均勻的特點,且粉末油脂復(fù)水以后在室溫下放置6小時也不析油、不分層,說明RG蛋白對氫化椰子油具有很好的包埋特性。單甘酯的加入會與RG蛋白發(fā)生競爭吸附,引起界面膜彈性模量的顯著下降,不利于乳狀液穩(wěn)定性。7S與單甘酯可以形成300 nm左右的乳狀液,但是噴霧干燥后制備的粉末油脂大多出現(xiàn)粘結(jié)現(xiàn)象,可能與7S在噴霧干燥過程中發(fā)生部分變性有關(guān)。本課題為高乳化性大豆蛋白產(chǎn)品的制備和應(yīng)用提供了新思路。
[Abstract]:The soybean protein is a plant protein resource with large yield and low price. In the past few decades, many studies have been made on how to improve the functional properties of soybean protein structure, and there are a lot of research on how to improve its processing function, such as emulsibility, foamability, gel property and so on. however, to date, that nature of the processing function of the soy protein-modified product aft the structural modification, for example, the emulsifying property, is, for example, significantly higher than that of the soy protein isolate or the concentrate protein, but has not yet been of high commercial value, High-emulsifying soybean protein product comparable to that of sodium caseinate and the like. In this paper, the structure modification of soybean protein was carried out by means of enzyme hydrolysis and glycosylation modification, and the aim of this study was to study and develop a high-emulsifying soybean protein. At the same time, based on the research on the rheological property of the soybean protein interface with different structure, the action mechanism of the macromolecular emulsifier with good emulsifying property in the oil-water two-phase interface and the required structural characteristics are further clarified. In ord to better develop and apply soybean protein as a surface-active substance and a colloid stabilizer to provide that theoretical foundation and the guidance. The effect of the combination of restriction enzyme hydrolysis and glycosylation on the emulsifying properties and interface properties of soybean protein was studied. It has been found that the most advantageous effect of the soybean protein hydrolysate on the emulsifying properties is the large molecular weight fraction (Mw30 k Da), and the small molecular weight soybean peptide has poor emulsifying properties. The results of the glycosylation of the peptide show that, with the increase of the mass of the sugar molecules, the emulsion stability of the glycosylated soybean peptide is gradually increased. The combination of the sugar can reduce the surface hydrophobicity and the net charge of the soybean peptide, reduce the repulsion action between the peptide chains, and increase the adsorption amount of the interface. The surface activity assay found that the soybean peptide-dextran copolymer is closely aligned on the interface and each molecule occupies a very small area. The laser confocal microscope showed that the soybean peptide-glucan copolymer can form a thick adsorption layer on the surface of the oil droplet. The interface rheological test shows that the soybean peptide can form an interface film with high viscoelasticity and wide linear viscoelastic region at the interface, and the soybean peptide and the glucan copolymer can form multi-layer adsorption on the interface. The results show that the soybean peptide-glucan copolymer has good surface properties, can be closely arranged on the interface and form an interface film with a certain thickness, and the oil drops can be wrapped to improve the stability of the emulsion system. On this basis, based on the purpose of retaining the large molecular weight part of the soybean hydrolysate, the effect of selective enzymatic hydrolysis (hydrolysis of the part of the soybean protein 11S and the retention of the 7S part) on the emulsifying properties and the interface properties of the soy protein was studied. The interface properties of proteins with different structures and the mechanism of stable emulsion were studied by means of SPI limited hydrolysis, selective hydrolysis of 11S, 7S and SPI. The results showed that the emulsifying properties of the soybean protein after the selective enzymatic hydrolysis of the 11S were significantly higher, which could be compared with that of the 7S protein and the sodium caseinate. The protein-stable emulsion can be adopted in two ways: one is a protein (such as sodium caseinate) which is flexible in structure and has a rod-like structure, The emulsion is stabilized by forming a thick interfacial film, and the other is a spherical protein having a smaller molecular weight (e.g., 7S), which can form a highly viscoelastic interface film on the interface to protect the oil droplets from flocculation and coagulation. The RG has both a spherical structure (7S) and a structurally flexible hydrolyzed peptide, so that the formed interface film has two advantages of high modulus and large interface adsorption capacity, and can form a stable emulsion. In order to investigate whether the 7S and RG proteins with good emulsifying ability in the above-mentioned studies have the potential to further enhance the emulsifying ability, the effects of the covalent and non-covalent bonding of the dextran on the emulsifying properties of the 7S and RG proteins are studied. The results show that, whether or not the particle size of the RG is increased, the net charge amount of the surface decreases, and the prepared emulsion particle size is small, but the emulsion stability is slightly lower than that of the sodium caseinate under the condition of acid and high salt ion concentration. It is possible that the presence of small molecular weight peptide moieties in the RG protein is detrimental to the stability of the emulsion. The emulsion prepared from the 7S, whether in the combination of a covalent bond and a glucan, is obviously superior to the sodium caseinate under the acidic condition, and the emulsion prepared by the sodium caseinate has good stability under the condition of high salt ion concentration, The stability of the emulsion prepared with the glycosylation product of the 7S and the dextran is only after the sodium caseinate. In order to further improve the stability of 7S at the isoelectric point, two anionic polysaccharides, soluble soybean polysaccharides (SSPS) and gum arabic (GA), which have the same surface activity, were selected to be combined with 7S, respectively. The effects of two kinds of polysaccharides on the rheological properties of the gas-water interface and the oil-water interface were also studied. The results showed that the effect of two polysaccharides on the adsorption of 7S on the two interfaces was completely different. For 7S-SSPS, in the gas-water interface, the adsorption behavior of the complex is dominated by 7S, and the adsorption rate is slower than that of the individual 7S. On the contrary, in the oil-water interface, the adsorption behavior of the complex is dominated by the SSPS and then becomes 7S-dominated. The stability of the emulsion shows that the emulsion formed by the 7S-SSPS is completely unaffected by the p H, and has good stability even in the vicinity of the isoelectric point of the 7S. It is possible that the SSPS combined with the 7S is tightly wound around the 7S and acts as a stabilizing emulsion by the steric hindrance effect. The addition of GA does not improve the stability of the 7S emulsion near the isoelectric point, mainly because the adsorption behavior of the interface is dominated by GA, and the emulsion formed by GA is also affected by the p H. Surprisingly, no matter the presence of the polysaccharide, the 7S can form an interfacial film with a high viscosity elastic modulus under any of the p H conditions, indicating that the layered phenomenon of the emulsion at the isoelectric point is mainly due to the electrostatic interaction between the droplets, regardless of the mechanical strength of the interface film. Finally, the application effect of 7S and RG with high emulsifying ability in the powder and oil system was studied. When the hydrogenated coconut oil is a core material, the RG protein is an emulsifying agent, and when the protein content reaches 6% or higher, the emulsion formed before the spray drying, the powder oil prepared after the spray drying, or the emulsion formed by the powder grease and the water after the spray drying have a small particle size, The method has the characteristics of uniform distribution, and after the powder oil and grease are mixed with water, the oil is left at room temperature for 6 hours, and the oil is not separated, so that the RG protein has good embedding characteristics for hydrogenated coconut oil. The addition of the monoglyceride can compete with the RG protein to cause a significant decrease of the elastic modulus of the interface film, which is not conducive to the stability of the emulsion. May be related to the partial denaturalization of the 7s during the spray drying process. This subject provides a new thought for the preparation and application of high-emulsifying soybean protein products.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TS201.21
本文編號：2478027
[Abstract]:The soybean protein is a plant protein resource with large yield and low price. In the past few decades, many studies have been made on how to improve the functional properties of soybean protein structure, and there are a lot of research on how to improve its processing function, such as emulsibility, foamability, gel property and so on. however, to date, that nature of the processing function of the soy protein-modified product aft the structural modification, for example, the emulsifying property, is, for example, significantly higher than that of the soy protein isolate or the concentrate protein, but has not yet been of high commercial value, High-emulsifying soybean protein product comparable to that of sodium caseinate and the like. In this paper, the structure modification of soybean protein was carried out by means of enzyme hydrolysis and glycosylation modification, and the aim of this study was to study and develop a high-emulsifying soybean protein. At the same time, based on the research on the rheological property of the soybean protein interface with different structure, the action mechanism of the macromolecular emulsifier with good emulsifying property in the oil-water two-phase interface and the required structural characteristics are further clarified. In ord to better develop and apply soybean protein as a surface-active substance and a colloid stabilizer to provide that theoretical foundation and the guidance. The effect of the combination of restriction enzyme hydrolysis and glycosylation on the emulsifying properties and interface properties of soybean protein was studied. It has been found that the most advantageous effect of the soybean protein hydrolysate on the emulsifying properties is the large molecular weight fraction (Mw30 k Da), and the small molecular weight soybean peptide has poor emulsifying properties. The results of the glycosylation of the peptide show that, with the increase of the mass of the sugar molecules, the emulsion stability of the glycosylated soybean peptide is gradually increased. The combination of the sugar can reduce the surface hydrophobicity and the net charge of the soybean peptide, reduce the repulsion action between the peptide chains, and increase the adsorption amount of the interface. The surface activity assay found that the soybean peptide-dextran copolymer is closely aligned on the interface and each molecule occupies a very small area. The laser confocal microscope showed that the soybean peptide-glucan copolymer can form a thick adsorption layer on the surface of the oil droplet. The interface rheological test shows that the soybean peptide can form an interface film with high viscoelasticity and wide linear viscoelastic region at the interface, and the soybean peptide and the glucan copolymer can form multi-layer adsorption on the interface. The results show that the soybean peptide-glucan copolymer has good surface properties, can be closely arranged on the interface and form an interface film with a certain thickness, and the oil drops can be wrapped to improve the stability of the emulsion system. On this basis, based on the purpose of retaining the large molecular weight part of the soybean hydrolysate, the effect of selective enzymatic hydrolysis (hydrolysis of the part of the soybean protein 11S and the retention of the 7S part) on the emulsifying properties and the interface properties of the soy protein was studied. The interface properties of proteins with different structures and the mechanism of stable emulsion were studied by means of SPI limited hydrolysis, selective hydrolysis of 11S, 7S and SPI. The results showed that the emulsifying properties of the soybean protein after the selective enzymatic hydrolysis of the 11S were significantly higher, which could be compared with that of the 7S protein and the sodium caseinate. The protein-stable emulsion can be adopted in two ways: one is a protein (such as sodium caseinate) which is flexible in structure and has a rod-like structure, The emulsion is stabilized by forming a thick interfacial film, and the other is a spherical protein having a smaller molecular weight (e.g., 7S), which can form a highly viscoelastic interface film on the interface to protect the oil droplets from flocculation and coagulation. The RG has both a spherical structure (7S) and a structurally flexible hydrolyzed peptide, so that the formed interface film has two advantages of high modulus and large interface adsorption capacity, and can form a stable emulsion. In order to investigate whether the 7S and RG proteins with good emulsifying ability in the above-mentioned studies have the potential to further enhance the emulsifying ability, the effects of the covalent and non-covalent bonding of the dextran on the emulsifying properties of the 7S and RG proteins are studied. The results show that, whether or not the particle size of the RG is increased, the net charge amount of the surface decreases, and the prepared emulsion particle size is small, but the emulsion stability is slightly lower than that of the sodium caseinate under the condition of acid and high salt ion concentration. It is possible that the presence of small molecular weight peptide moieties in the RG protein is detrimental to the stability of the emulsion. The emulsion prepared from the 7S, whether in the combination of a covalent bond and a glucan, is obviously superior to the sodium caseinate under the acidic condition, and the emulsion prepared by the sodium caseinate has good stability under the condition of high salt ion concentration, The stability of the emulsion prepared with the glycosylation product of the 7S and the dextran is only after the sodium caseinate. In order to further improve the stability of 7S at the isoelectric point, two anionic polysaccharides, soluble soybean polysaccharides (SSPS) and gum arabic (GA), which have the same surface activity, were selected to be combined with 7S, respectively. The effects of two kinds of polysaccharides on the rheological properties of the gas-water interface and the oil-water interface were also studied. The results showed that the effect of two polysaccharides on the adsorption of 7S on the two interfaces was completely different. For 7S-SSPS, in the gas-water interface, the adsorption behavior of the complex is dominated by 7S, and the adsorption rate is slower than that of the individual 7S. On the contrary, in the oil-water interface, the adsorption behavior of the complex is dominated by the SSPS and then becomes 7S-dominated. The stability of the emulsion shows that the emulsion formed by the 7S-SSPS is completely unaffected by the p H, and has good stability even in the vicinity of the isoelectric point of the 7S. It is possible that the SSPS combined with the 7S is tightly wound around the 7S and acts as a stabilizing emulsion by the steric hindrance effect. The addition of GA does not improve the stability of the 7S emulsion near the isoelectric point, mainly because the adsorption behavior of the interface is dominated by GA, and the emulsion formed by GA is also affected by the p H. Surprisingly, no matter the presence of the polysaccharide, the 7S can form an interfacial film with a high viscosity elastic modulus under any of the p H conditions, indicating that the layered phenomenon of the emulsion at the isoelectric point is mainly due to the electrostatic interaction between the droplets, regardless of the mechanical strength of the interface film. Finally, the application effect of 7S and RG with high emulsifying ability in the powder and oil system was studied. When the hydrogenated coconut oil is a core material, the RG protein is an emulsifying agent, and when the protein content reaches 6% or higher, the emulsion formed before the spray drying, the powder oil prepared after the spray drying, or the emulsion formed by the powder grease and the water after the spray drying have a small particle size, The method has the characteristics of uniform distribution, and after the powder oil and grease are mixed with water, the oil is left at room temperature for 6 hours, and the oil is not separated, so that the RG protein has good embedding characteristics for hydrogenated coconut oil. The addition of the monoglyceride can compete with the RG protein to cause a significant decrease of the elastic modulus of the interface film, which is not conducive to the stability of the emulsion. May be related to the partial denaturalization of the 7s during the spray drying process. This subject provides a new thought for the preparation and application of high-emulsifying soybean protein products.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TS201.21
【參考文獻】
相關(guān)期刊論文 前4條
1 閆潔;馬曉軍;;不同干燥方式對大豆蛋白二級結(jié)構(gòu)的影響[J];食品工業(yè)科技;2008年05期
2 劉欣,徐紅華,李鐵晶;微生物蛋白酶改性大豆分離蛋白的研究進展[J];大豆通報;2005年04期
3 趙國志,劉喜亮,中里真人,朱律;中碳鏈脂肪酸甘油酯的研究概況[J];糧油加工與食品機械;2005年02期
4 孫桂華;粉末油脂配方的研究[J];糧食與油脂;2003年S1期
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