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乳蛋白为人体提供必需氨基酸,生物利用率高,是优质的蛋白质来源。在乳制品加工过程中,热处理会改变乳蛋白的空间结构及化学修饰,从而对乳蛋白的消化特性产生影响。热处理程度越剧烈,乳蛋白在胃中形成的凝块越松软,且变性乳清蛋白形成的聚集体有利于胃蛋白酶的消化。同时,热处理也改变了胃消化动力学及乳蛋白衍生生物活性肽的释放。热处理诱导的化学修饰如美拉德反应产物被认为降低了整体消化率,但近期研究也指出了其作为益生元的潜在功能。文章梳理了热处理对乳蛋白结构、功能性和营养性的影响,以期为乳制品的热处理工艺优化提供借鉴。 相似文献
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利用三种模拟生产加热处理,来研究鲜牛乳和复原乳蛋白多态性变化。通过调控pH和加热温度,发现鲜牛乳和复原乳中α-乳白蛋白、β-乳球蛋白、非沉淀酪蛋白和蛋白胶束的粒径大小均变化差异显著。 相似文献
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乳蛋白在非常规的条件下,通过控制聚合程度,会形成一种特殊结构的蛋白质聚合物,即微米凝胶。研究了这种微凝胶与常规乳蛋白聚合物之间的差异,分析了浊度、Zeta-电位、DSC及流变学性质的变化。 相似文献
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为了进一步了解不同因素对鸡蛋蛋白质凝胶特性的影响,国内外研究者已经针对性的进行了大量的研究工作。本文综合论述了鸡蛋中蛋白质的组成和凝胶的形成机理,分析了温度、压力、pH、酶、盐、蛋白质浓度、处理时间等因素对鸡蛋蛋白质凝胶特性的影响,其中温度、压力、pH、盐、处理时间几个因素对鸡蛋蛋白质凝胶特性的影响研究已较为全面,但生物酶对鸡蛋蛋白凝胶特性的影响研究相对较少,所研究的酶种类较为单一。通过对这些影响因素的研究状况进行综述,以期为鸡蛋深加工过程中工艺参数的控制提供一定依据,为进一步提升鸡蛋加工产品的凝胶品质提供理论参考。 相似文献
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牛乳及乳制品具有重要的营养价值,但是牛乳过敏会导致患者出现呼吸道问题,严重者甚至会休克或死亡,因此低致敏乳制品的研发具有重要意义。目前常见的牛乳脱敏技术被分为物理法、化学法和生物法,其中生物法更具有前景。简述了牛乳的主要过敏蛋白,阐述了生物酶法、发酵作用和转基因技术这3种生物脱敏技术。其中生物酶法仍然是目前最具有前景的生物降敏方法,水解酶将蛋白质降解为小分子多肽,但在降敏的同时会产生苦味物质,因此,近年来交联酶在该领域的作用逐渐被重视。发酵作用可以降低牛乳致敏性,但其降低程度有限,需与其他处理联合使用。转基因技术可以通过对线性表位氨基酸进行突变,以降低牛乳致敏性。另外,介绍了目前常见的几种牛乳致敏性检测方法,以期望为未来低致敏乳制品的研究提供理论依据。 相似文献
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Hong Wang Yunna Wang Jialu Cao Dongdong Yuan Liankun Chen Jie Han Yan Li Liebing Zhang 《Journal of dairy science》2018,101(6):4977-4982
This study aimed to evaluate the effects of different concentration methods (nanofiltration and evaporation) and heat treatments on the gel properties of milk protein concentrate (MPC). The MPC gels were produced using glucono-δ-lactone (GDL) as an acidifier with different preheat treatments (30 min at 80°C and 5 min at 92°C). We then evaluated the effect of preheat treatments on MPC gel properties, including storage modulus (G′), loss tangent (tan δ), firmness, whey separation, and microstructure. The results indicated that without preheating, evaporation (EP)-MPC had higher G′ and firmness, and lower tan δ and whey separation than nanofiltration (NF)-MPC. These results suggest that EP-MPC produced a better acid-induced gel than NF-MPC when no preheat treatments were performed. After preheating, however, except for a very small difference in the final G′ (EP-MPC was higher), the 2 MPC did not differ significantly in firmness, final tan δ, or whey separation. Additionally, compared with the gel of unheated MPC, both preheat-treated gels (NF-MPC and EP-MPC) achieved increased G′ and firmness and decreased tan δ and whey separation. The preheat-treated MPC also displayed a more flexible-stranded network. These findings demonstrate that, given a suitable heating treatment, NF-MPC compares favorably with EP-MPC in achieving desired gel properties. 相似文献
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Yingchen Lin Alan L. Kelly James A. OMahony Timothy P. Guinee 《Journal of dairy science》2018,101(8):6799-6813
Milk protein concentrate (MPC) powders (~81% protein) were made from skim milk that was heat treated at 72°C for 15 s (LHMPC) or 85°C for 30 s (MHMPC). The MPC powder was manufactured by ultrafiltration and diafiltration of skim milk at 50°C followed by spray drying. The MPC dispersions (4.02% true protein) were prepared by reconstituting the LHMPC and MHMPC powders in distilled water (LHMPCw and MHMPCw, respectively) or milk permeate (LHMPCp and MHMPCp, respectively). Increasing milk heat treatment increased the level of whey protein denaturation (from ~5 to 47% of total whey protein) and reduced the concentrations of serum protein, serum calcium, and ionic calcium. These changes were paralleled by impaired rennet-induced coagulability of the MHMPCw and MHMPCp dispersions and a reduction in the pH of maximum heat stability of MHMPCp from pH 6.9 to 6.8. For both the LHMPC and MHMPC dispersions, the use of permeate instead of water enhanced ethanol stability at pH 6.6 to 7.0, impaired rennet gelation, and changed the heat coagulation time and pH profile from type A to type B. Increasing the severity of milk heat treatment during MPC manufacture and the use of permeate instead of water led to significant reductions in the viscosity of stirred yogurt prepared by starter-induced acidification of the MPC dispersions. The current study clearly highlights how the functionality of protein dispersions prepared by reconstitution of high-protein MPC powders may be modulated by the heat treatment of the skim milk during manufacture of the MPC and the composition of the solvent used for reconstitution. 相似文献
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由于牛奶蛋白复合纤维染整加工中经常伴随着湿热加工,因此,着重研究了湿热处理对牛奶蛋白复合纤维结构和性能的影响.结果表明,湿热处理对牛奶蛋白复合纤维的收缩率、强力、白度及表面形态影响显著,对牛奶蛋白复合纤维结构及结晶形态影响很小.随着湿热处理温度的升高,牛奶蛋白复合纤维织物的顶破强力稳步提高,而白度出现下降;当湿热处理温度大于100℃时,收缩率的增幅明显变大,且手感变硬;特别当湿热处理温度超过130℃时,纤维的表面已经几乎没有平整的地方.因此,牛奶蛋白复合纤维宜采用90、100℃为其最高湿热加工温度. 相似文献
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Different milk protein concentrates (MPC), with protein concentrations of 56, 70, and 90%, were dispersed in water under different treatments (hydration, shear, heat, and overnight storage at 4°C), as well as in a combination of all the treatments in a factorial design. The particle size distribution of the dispersions was then measured to determine the optimal conditions for the dispersion. Heating at 60°C for 30 min with 5 min of shear was chosen as the best condition to dissolve MPC powders. The samples were also characterized for composition, presence of protein aggregates, and ratio of calcium to protein. The total calcium present in MPC increased with increasing concentration of protein; however, the total calcium-to-protein ratio was lower in MPC90 than in MPC56 and MPC70. The level of whey protein denaturation, the presence of κ-casein-whey protein aggregates in the supernatant after centrifugation, and the amount of caseins dissociated from the micelle increased as the protein concentration in the powder increased. The total amount of casein macropeptide released was lower in samples from powders with a higher protein concentration than for MPC56 or the skim milk control. The gelation behavior of reconstituted MPC was tested in systems dispersed in water (5% protein) as well as in systems dispersed in skim milk (6% protein). The gelation time of MPC dispersions was considerably lower and the gel modulus was higher than those of reconstituted skim milk with the same protein concentration. When MPC dispersions were dialyzed against skim milk, a significant decrease in the gelation time and modulus were shown, with a complete loss of gelling functionality in MPC90 dispersed in water. This demonstrated that the ionic equilibrium was key to the functionality of MPC. 相似文献
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Influence of milk protein cross‐linking by transglutaminase on the rennet coagulation time and the gel properties 下载免费PDF全文
Jacek Domagała Dorota Najgebauer‐Lejko Ilona Wieteska‐Śliwa Marek Sady Monika Wszołek Genowefa Bonczar Magda Filipczak‐Fiutak 《Journal of the science of food and agriculture》2016,96(10):3500-3507
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The effects of homogenization and heat treatment on the formation and the breakdown of clots during gastric digestion of whole milk were investigated using a human gastric simulator. Homogenization and heat treatment led to formation of coagula with fragmented and crumbled structures compared with the coagulum formed from raw whole milk, but a larger fraction of the protein and more fat globules were incorporated into the coagula induced by action of the milk-clotting enzyme pepsin. The fat globules in the whole milk appeared to be embedded in the clots as they formed. After formation of the clot, the greater numbers of pores in the structures of the clots formed with homogenized milk and heated whole milk led to greater rates of protein hydrolysis by pepsin, which resulted in faster release of fat globules from the clots into the digesta. Coalescence of fat globules occurred both in the digesta and within the protein clots no matter whether they were in homogenized or heated milk samples. The formation of clots with different structures and hence the changes in the rates of protein hydrolysis and the release of milk fat into the digesta in the stomach provide important information for understanding the gastric emptying of milk and the potential to use this knowledge to manipulate the bioavailability of fat and other fat-soluble nutrients in dairy products. 相似文献
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随着我国经济的发展,人民生活水平不断提高,乳制品成为日常饮食的重要组成部分。乳制品含有促进人体生长发育及维持健康必需的营养成分,驴乳、驼乳、牦牛乳等特种乳因其良好的营养价值而越来越受到人们欢迎。由于特种乳具有良好市场前景且其产量较低,目前市场中特种乳价格普遍高于牛乳,受经济利益驱动的影响,乳源掺假问题日益凸显,掺假鉴别成为近年来研究的热点。针对乳制品中乳源掺假问题,国内外研究学者已经建立了多种鉴别的方法,本文从基于核酸、蛋白、化合物的方法和智能无损检测四个方面对乳及乳制品乳源鉴别方法现状进行了概述,并对4种方法做出总结和比较,对未来需要解决的问题进行了探讨。 相似文献
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Clodagh M Kelleher Tugce Aydogdu Kevin M Murphy James A O'Mahony Alan L Kelly Donal J O'Callaghan Noel A McCarthy 《International Journal of Dairy Technology》2020,73(3):494-501
The effect of preheat temperature (63 or 77 °C for 30 s; final heat 120 °C for 30 s) and casein to whey protein ratio on the physical characteristics of 3.3%, w/w, dairy protein beverages was investigated. Dispersions preheated at 77 °C had lower viscosity than dispersions preheated at 63 °C. Casein‐containing dispersions had significantly lower levels of α‐lactalbumin denaturation than whey protein‐only dispersions. A higher proportion of casein improved the thermal stability of protein dispersions. Overall, alteration of preheat temperature and casein to whey protein ratio can influence dairy beverage quality, with increasing levels of casein reducing physical changes due to heat treatment. 相似文献