Raw skim milk was subjected to different heat treatments: thermization (65°C, 20 s), pasteurization (72°C, 15 s), and no heat treatment (milk was microfiltered using 1.4-µm membranes at 50°C for bacteria removal; 1.4 MF). The milk (thermized, pasteurized, and 1.4 MF) was cooled and stored at 2°C until processing (at least 24 h) with cold (∼6°C) microfiltration using a benchtop crossflow pilot unit (Pall Membralox XLAB 5, Pall Corp., Port Washington, NY) equipped with 0.1-µm nominal pore diameter ceramic Membralox membrane (ET1-070, α-alumina, Pall Corp.). The flux was monitored during the process, and β-casein transmission and removal were calculated. The study aimed to indicate the conditions that should be applied to maximize β-casein passage through the membrane during cold microfiltration (5.6 ± 0.4°C) of skim milk. The proper selection of heat treatment parameters (temperature, time) of the feed before the cold microfiltration process will increase β-casein removal. It is not clear whether the difference in β-casein transmission between 1.4 MF, thermized, and pasteurized milk results from the effect of heat treatment conditions on β-casein dissociation from the casein micelles or on passage of β-casein through the membrane. The values of the major parameters (permeation flux and tangential flow velocity, through the wall shear stress) responsible for a proper membrane separation process were considerably lower than the critical values. It seems that the viscosity of the retentate has a great effect on the performance of the microfiltration membranes for protein separation at refrigerated temperatures.

生脱脂奶经过不同的热处理：热化（65°C，20 s），巴氏灭菌（72°C，15 s），并且不进行热处理（使用1.4 µm膜在50°C下对牛奶进行微滤以去除细菌） ； 1.4 MF）。将牛奶（加热，巴氏灭菌和1.4 MF）冷却并在2°C下储存，直到使用台式横流先导装置（Pall Membralox XLAB 5，Pall Corp.）以冷（〜6°C）微滤处理（至少24小时）为止。 （美国纽约州华盛顿港）装有标称孔径为0.1 µm的Membralox陶瓷Membralox膜（ET1-070，α-氧化铝，颇尔公司）。在此过程中对通量进行了监控，并且计算β-酪蛋白的传递和去除。该研究旨在指出脱脂牛奶在冷微滤（5.6±0.4°C）期间应最大化β-酪蛋白通过膜的条件。在冷微滤过程之前正确选择进料的热处理参数（温度，时间）会增加β-酪蛋白的去除率。尚不清楚1.4 MF，热奶和巴氏杀菌奶之间的β-酪蛋白传递差异热处理条件对酪蛋白胶束中β-酪蛋白解离的影响或β-酪蛋白通过膜的通过的结果。负责适当的膜分离过程的主要参数（渗透通量和切向流速，通过壁切应力）的值大大低于临界值。似乎滞留物的粘度对在冷藏温度下用于蛋白质分离的微滤膜的性能有很大影响。