【作者】 陈林；

【导师】 徐幸莲；

【作者基本信息】 南京农业大学 ， 食品科学与工程， 2015， 硕士

【摘要】 近年来,随着人们生活水平的提高以及健康意识的增强,低脂肉制品越来越受到消费者的关注和喜爱,降低肉制品中脂肪含量成为研究的热点。为了降低肉制品中脂肪含量同时保证产品品质,许多脂肪替代物应运而生。脂肪替代物是指替代或部分替代脂肪作用的添加物。蛋白质-水-植物油预乳化物作为肉制品加工中动物性脂肪替代物,近年来已逐渐成为国际研究的发展方向。预乳化物因其在产品加工中具有凝胶保水性好、物理化学性质稳定且更利于保持肉糜乳化物稳定性等特点,已被应用于发酵香肠和法兰克福香肠加工,从而达到降低产品脂肪含量,改善产品脂肪酸组成的目的。而预乳化液的稳定性受pH及Na+浓度影响较大。同时,预乳化液中非肉蛋白在斩拌加工过程中会与肌肉中的肌原纤维蛋白在脂肪球表面发生竞争性吸附作用,进而有可能改变肉糜乳化体系的稳定性而影响产品品质。因此,本论文研究了 pH及Na+浓度对肌原纤维蛋白和鸡血浆蛋白乳化稳定性及二级结构的影响,在此基础上研究鸡血浆蛋白和肌原纤维蛋白在脂肪球表面的竞争性吸附乳化作用,并将鸡血浆蛋白与大豆油的预乳化液运用于实践,研究不同加工方式添加鸡血浆蛋白对低脂法兰克福肠品质的影响。研究结果如下:1、pH和Na+浓度对鸡血浆蛋白及肌原纤维蛋白乳化特性和蛋白质二级结构的影响随着pH和Na+浓度的升高,肌原纤维蛋白乳化液的粘度逐渐增大,当pH为6.5或7,Na+浓度为0.6mol/L时乳化液的粘度值最大,乳化液最稳定,此时乳化液分层不明显,蛋白质疏水性最弱,蛋白质α-螺旋百分含量最低,β-折叠百分含量最高。Na+浓度对鸡血浆蛋白乳化液的储藏稳定性、乳化液粘度、蛋白质疏水性以及二级结构无显著影响(P>0.05),而随着pH的升高,鸡血浆蛋白乳化液粘度值显著上升(P<0.05),蛋白质疏水性及α-螺旋百分含量显著降低,β-折叠百分含量显著升高(P<0.05),当pH值达到7.0时,鸡血浆蛋白乳化液粘度最大,疏水性最弱,αα-螺旋含量最低,β-折叠百分含量最高,此时乳化液分层现象最不明显。2、鸡血浆蛋白和肌原纤维蛋白竞争性吸附乳化作用的研究研究不同乳化顺序条件下肌原纤维蛋白和鸡血浆蛋白竞争性吸附乳化作用发现:鸡血浆蛋白与植物油、水预乳化再与肌原纤维蛋白乳化,得到乳化液具有更好的乳化稳定性、乳化活性;其粘度值也较大,得到的乳化液的粒径更小。通过比较乳化界面吸附蛋白质的组成成分及含量发现,鸡血浆蛋白和肌原纤维蛋白在脂肪表面发生竞争性吸附。鸡血浆蛋白预乳化处理组中,乳化液界面的鸡血浆蛋白含量显著高于其他处理组。3、不同加工方式添加鸡血浆蛋白对低脂法兰克福肠品质的影响通过添加鸡血浆蛋白降低法兰克福香肠中动物脂肪的含量,从物理化学性质、质构特性以及微观结构特性等方面比较了鸡血浆蛋白以预乳化方式添加和以蛋白粉直接添加的优缺点。结果表明:添加了鸡血浆蛋白的低脂法兰克福香肠与高脂对照组相比,卡路里含量和表观粘度显著降低,肉糜稳定性显著增加(P<0.05)。随着鸡血浆蛋白添加量的增加,法兰克福肠的蛋白质含量、灰分含量、黄度值、亮度值、压榨损失、弹性和内聚性显著升高(P<0.05),而法兰克福肠的硬度值显著下降(P<0.05)。鸡血浆蛋白预乳化添加方式与直接添加的方式相比,法兰克福香肠具有更高的保水性、更好的质构特性和更稳定的乳化特性,同时其微观结构更加均一。更多还原

【Abstract】 In recent years,with the improvement of people’s living standard and the enhancement of health consciousness,reduced-fat meat products have got more and more attention from consumers.Many researchers have studied reduced-fat foods.In order not to change the product quality,fat substitutes are appearing.Fat substitutes are important additives in food processing.Pre-emulsions as a replacement of animal fat have become a hot topic among the world researchers.Pre-emulsion is composed of fat,protein and water and it has good water-and fat-binding properties,stable physicochemical properties and more conducive to keep the mince emulsify material stability,etc.Pre-emulsions have been used in the fermented sausage and Frankfurt sausage,so as to achieve lower fat content and change the fatty acid composition of meat products.The emulsion stability is affected by the pH and sodium concentration,and also some studies have shown that the protein of pre-emulsions is likely to do competitive adsorption in the fat surface with the myofibril protein,which may cause the composition and stability of the emulsion system changing.So,in this paper,firstly,the effect of different pH and sodium concentration on emulsion stability and secondary structure of myofibril protein and chicken plasma protein have been studied.Secondly,the competitive adsorption in fat surface of emulsion between chicken plasma protein and myofibril protein have been studied.Finally,we studied the effect of soybean oil emulsified and un-emulsified with chicken plasma protein on the physicochemical properties of reduced-fat frankfurters.The contents and results were as follows:1、Effect of different pH and sodium concentration on emulsion stability and secondary structure of myofibril protein and chicken plasma proteinWith the pH and sodium concentration increasing,the emulsifying viscosity of myofibril protein increased,it was highest when the pH was 6.5 or 7.0 and sodium concentration was 0.6mol/L,and also had better emulsifying stability,lower surface hydrophobicity and a-helix content,higher β-sheet content.Different sodium concentrations have no obvious influence on chicken plasma protein.With the pH increasing,the emulsifying viscosity and β-sheet content of chichen blood plasma obviously increased(P<0.05),surface hydrophobicity and α-helix content decreased(P<0.05).When pH was 7.0,chicken plasma protein had higest emulsifying viscosity and[-sheet content,lowest surface hydrophobicity and a-helix content and the emulsifying stability was better(P<0.05).2.Study on the competitive adsorption emulsion between chicken plasma protein and myofibril proteinResearch the effect of different emulsifying order on the competitive adsorption emulsifying between chicken plasma protein and myofibril protein found that chicken plasma protein,vegetable oil and water was emulsified firstly,and then emulsified with myofibril protein,the emulsion had better emulsifying stability,emulsifying activity,its viscosity value is also highest,the particle size of emulsion was smaller.By comparing the emulsion interface adsorption of protein composition and content found that chicken plasma protein and myofibril protein had competitive adsorption in the surface of the fat.3、Effect of soybean oil emulsified and un-emulsified with chicken plasma protein on the physicochemical properties of reduced-fat frankfurtersThe effects of reduced pork back-fat levels from 30%to 20%,15%and 10%with addition of chicken plasma protein(CPP)as a powder additive or as a emulsifier in pre-emulsified soybean oil(SO)on the physicochemical properties,texture and microstructure of frankfurters were investigated.Reduced-fat frankfurters containing CPP had low energy contents and apparent viscosity,showed good emulsion stability compared with the control with 30%fat.With increasing substitution of pork back-fat,frankfurters containing CPP showed higher protein and ash contents(P<0.05),were more yellow and lighter in color,had increased weight loss by pressing,higher springiness and cohesiveness(P<0.05),while the hardness of frankfurters became lower(P<0.05).Utilize CPP as a stabilizer in pre-emulsified soybean oil was beneficial for water hold capacity,texture profile analysis,emulsion stability,apparent viscosity(P<0.05)and gave a homogeneous distribution of fat globules in frankfurters compared to those where CPP was added as a powder additive.更多还原