【作者】 李玉美；

【导师】 许时婴； 卢蓉蓉；

【作者基本信息】 江南大学 ， 食品科学， 2006， 硕士

【摘要】 随着社会的发展,人们的消费观和价值观在不断地发生变化。食品中的脂肪含量越来越受到人们的关注,过量的脂肪摄入会引发许多健康问题,随之出现了脂肪替代品。以蛋白质为基质的脂肪替代品的开发研究最早开始于20世纪80年代,我国在这方面还没有开展深入的研究。乳清蛋白形成的热诱导性凝胶,经微粒化工艺处理,可以使其凝胶颗粒达到10μm左右,这种处于舌头感官阈值之下的微细粒子,食用时可产生类似脂肪的稠度和滑腻感。本文以乳清浓缩蛋白和酶法改性的乳清浓缩蛋白为基质,分别制备了脂肪替代品,并将其应用于低脂冰淇淋。首先,研究了乳清蛋白溶液的流变特性,确定了脂肪替代品的制备工艺。选择制备脂肪替代品的原料为乳清浓缩蛋白WPC-80、pH值7.0、WPC-80浓度为0.10 g/mL、无水CaC_l2的浓度为0.003 g/mL、黄原胶的浓度为0.005 g/mL、热处理温度为80℃。应用Alcalase 2.4L蛋白酶对乳清蛋白进行改性,分别以水解度2%～5%的酶解乳清蛋白制备脂肪替代品。脂肪替代品的硬度、酥脆性、胶着性、咀嚼度以及粘着性会随着乳清蛋白水解度的增加,基本呈下降趋势。以乳清蛋白为基质的脂肪替代品是假塑性流体,随着乳清蛋白水解度的增加,制备的脂肪替代品的粘度下降、亮度下降、黄度增加。未经酶解的乳清蛋白制备的脂肪替代品质构与奶油相似,水解度为3%的酶解乳清蛋白制备的脂肪替代品质构与氢化棕榈油相似。采用粒径分布仪测定脂肪替代品制备过程中粒径分布的变化。在乳清蛋白溶液中,50%的颗粒在133.2μm以下。当形成凝胶后,50%的颗粒在334.9μm以下,微粒化处理15 min后,50%的颗粒在10μm左右,可以模拟脂肪的特性。采用扫描电镜观察脂肪替代品制备过程中超微结构的变化,结果显示:乳清蛋白溶液中,蛋白质颗粒均匀分散,颗粒较小;热处理后蛋白质颗粒膨胀,并形成了凝胶,表面粗糙,但没有显示脂肪的光滑构造;而微粒化处理后的蛋白质凝胶表面变得光滑、柔软,可以作为脂肪替代品。将上述脂肪替代品应用于低脂冰淇淋中,替代普通中脂冰淇淋中25%的脂肪。研究结果表明,低脂冰淇淋的各项感官指标均与中脂冰淇淋相当。当乳清蛋白的水解度为4%时,制得的低脂冰淇淋的各项感官指标均优于其它试样。感官评定结果表明,随着替代比例增大,所制得的无脂冰淇淋也能够被接受。更多还原

【Abstract】 Along with the society’s development, people’s attitude towards consumption and the values changes continually. Fat content in food receives increasing attention from people. Excessive consumption of fat may lead to many health problems, which led to appearance of fat replacers. Whey protein-based fat replacers research first began in 1980. Research in this area in China is in its infancy. Whey protein can be made into fat replacers because of its gelling properties. When they were microparticulated, 50% of particle size is about 10μm in diameter. They may have the similar fat thickness and the slippery soapy feeling. Fat replacers were applied to ice-cream. The fat replacers include native and enzyme hydrolysed whey protein-based.Firstly, we studied several rheological properties of whey protein and confirmed the preparation method of fat replacers. WPC-80 as raw material and pH 7.0 were chosen. The concentration of WPC-80 was 0.10 g/mL,the concentration of CaCl2 was 0.003 g/mL,the concentration of Xanthan was 0.005 g/mL and the temperature of heating was 80℃.Secondly, we studied the enzyme hydrolysed whey protein-based fat replacers. The fat replacer based on WPC-80 of different degrees of hydrolysis (DH) were obtained from the whey protein by hydrolysis with Alcalase 2.4L to produce semisolid fat imitations to be used as fat replacers. The hardness, fracturability, gumminess and chewiness of fat replacers reduced basically as DH increased. With increasing DH, the Viscosity and the light (L) of the fat replacers reduced, while the yellow increased. The texture profile analysis (TPA) of control was similar with white creamer and the TPA of DH 3% was similar with hydrogenated palm oil.During fat replacer preparation, we examined the size distribution. In whey protein solution, 50% of particle size is smaller than 133.2μm in diameter. After gel formation the, fifty percent of particle became smaller than 334.9μm. The particles become smaller when they were microparticulated in 15 minutes. Fifty percent of particle size was about 10μm. During the preparation fat replacers, we examined the microstructure of whey protein by scanning electron microscope (SEM). In whey protein solution, whey protein particles evenly dispersed and the particle size was small. After heat treatment, whey protein inflat, and they formed the gel. The surface of them is rough and unable to simulate the slippery feeling. After microparticulation, the surface of protein gels became smooth and soft. They could be used as fat replacers.更多还原