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Effect of processing methods and protein content of the concentrate on the properties of milk protein concentrate with 80% protein
Journal of Dairy Science ( IF 3.5 ) Pub Date : 2018-06-21 , DOI: 10.3168/jds.2018-14383
L.S. Rupp , M.S. Molitor , J.A. Lucey

In recent years, a large increase in the production of milk protein concentrates (MPC) has occurred. However, compared with other types of milk powders, few studies exist on the effect of key processing parameters on powder properties. In particular, it is important to understand if key processing parameters contribute to the poor solubility observed during storage of high-protein MPC powders. Ultrafiltration (UF) and diafiltration (DF) are processing steps needed to reduce the lactose content of concentrates in the preparation of MPC with a protein content of 80% (MPC80). Evaporation is sometimes used to increase the TS content of concentrates before spray drying, and some indications exist that inclusion of this processing step may affect protein properties. In this study, MPC80 powders were manufactured by 2 types of concentration methods: membrane filtration with and without the inclusion of an evaporation step. Different concentration methods could affect the mineral content of MPC powders, as soluble salts can permeate the UF membrane, whereas no mineral loss occurs during evaporation, although a shift in calcium equilibrium toward insoluble forms may occur at high protein concentration levels. It is more desirable from an energy efficiency perspective to use higher total solids in concentrates before drying, but concerns exist about whether a higher protein content would negatively affect powder functionality. Thus, MPC80 powders were also manufactured from concentrates that had 3 different final protein concentrations (19, 21, and 23%; made from 1 UF retentate using batch recirculation evaporation, a similar concentration method). After manufacture, powders were stored for 6 mo at 30°C to help understand changes in MPC80 properties that might occur during shelf-life. Solubility and foaming properties were determined at various time points during high-temperature powder storage. Inclusion of an evaporation step, as a concentration method, resulted in MPC80 that had higher ash, total calcium, and bound calcium (of rehydrated powder) contents compared to concentration with only membrane filtration. Concentration method did not significantly affect the bulk (tapped) density, solubility, or foaming properties of the MPC powders. Powder produced from concentrate with 23% protein content exhibited a higher bulk density and powder particle size than powder produced from concentrate that had 19% protein. The solubility of MPC80 powder was not influenced by the protein content of the concentrate. The solubility of all powders significantly decreased during storage at 30°C. Higher protein concentrations in concentrates resulted in rehydrated powders that had higher viscosities (even when tested at a constant protein concentration). The protein content of the concentrate did not significantly affect foaming properties. Significant changes in the mineral content are used commercially to improve MPC80 solubility. However, although the concentration method did produce a small change in the total calcium content of experimental MPC80 samples, this modification was not sufficiently large enough (<7%) to influence powder solubility.



中文翻译:

浓缩液的加工方法和蛋白质含量对蛋白质含量为80%的牛奶浓缩蛋白性能的影响

近年来,牛奶浓缩蛋白(MPC)的生产已大幅度增加。但是,与其他类型的奶粉相比,关于关键加工参数对奶粉性能的影响的研究很少。特别是,重要的是要了解关键加工参数是否会导致在存储高蛋白MPC粉末期间观察到的不良溶解性。超滤(UF)和渗滤(DF)是减少蛋白质含量为80%(MPC80)的MPC制备中降低浓缩物中乳糖含量所需的加工步骤。有时会使用蒸发来增加喷雾干燥前精矿中TS的含量,并且存在一些迹象表明该加工步骤的加入可能会影响蛋白质特性。在这项研究中,MPC80粉末是通过两种浓缩方法制造的:膜过滤,包括和不包括蒸发步骤。不同的浓缩方法可能会影响MPC粉末的矿物质含量,因为可溶性盐会渗透到UF膜中,而在蒸发过程中不会发生矿物质损失,尽管在高蛋白浓度下钙平衡可能会向不溶形式转移。从能量效率的角度来看,更希望在干燥之前在浓缩物中使用较高的总固体,但是存在着关于较高的蛋白质含量是否会对粉末的功能性产生负面影响的担忧。因此,MPC80粉末也由具有3种不同最终蛋白质浓度(19%,21%和23%;使用分批循环蒸发法,类似浓缩方法的1个UF截留液)制成的浓缩物制成。制造后 粉末在30°C下保存6个月,以帮助了解MPC80特性在保质期内可能发生的变化。在高温粉末储存期间的各个时间点测定溶解度和起泡性能。与仅进行膜过滤的浓缩相比,将蒸发步骤作为浓缩方法包括在内,会使MPC80的灰分,总钙和(再水化粉末的)结合钙含量更高。浓缩方法没有显着影响MPC粉末的堆积(堆积)密度,溶解度或起泡性能。由蛋白质含量为23%的浓缩物生产的粉末比由蛋白质含量为19%的浓缩物生产的粉末具有更高的堆积密度和粉末粒度。MPC80粉末的溶解度不受浓缩物蛋白质含量的影响。在30°C下储存期间,所有粉末的溶解度均显着降低。浓缩物中较高的蛋白质浓度导致再水化的粉末具有较高的粘度(即使在恒定的蛋白质浓度下进行测试)。浓缩物的蛋白质含量没有显着影响发泡性能。矿物质含量的显着变化可用于商业目的,以提高MPC80的溶解度。但是,尽管浓缩方法的确在实验MPC80样品中的总钙含量上产生了很小的变化,但是这种修饰的幅度不足以影响粉末的溶解度(<7%)。浓缩物中较高的蛋白质浓度导致再水化的粉末具有较高的粘度(即使在恒定的蛋白质浓度下进行测试)。浓缩物的蛋白质含量没有显着影响发泡性能。矿物质含量的显着变化可用于商业目的,以提高MPC80的溶解度。但是,尽管浓缩方法的确在实验MPC80样品中的总钙含量上产生了很小的变化,但是这种修饰的幅度不足以影响粉末的溶解度(<7%)。浓缩物中较高的蛋白质浓度导致再水化的粉末具有较高的粘度(即使在恒定的蛋白质浓度下进行测试)。浓缩物的蛋白质含量没有显着影响发泡性能。矿物质含量的显着变化可用于商业目的,以提高MPC80的溶解度。但是,尽管浓缩方法的确在实验MPC80样品中的总钙含量上产生了很小的变化,但是这种修饰的幅度不足以影响粉末的溶解度(<7%)。

更新日期:2018-06-22
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