Babu K S, Amamcharla J K
Department of Animal Sciences and Industry/Food Science Institute, Kansas State University, Manhattan 66506.
JDS Commun. 2021 Sep 13;2(6):313-318. doi: 10.3168/jdsc.2021-0125. eCollection 2021 Nov.
Electrical resistance tomography (ERT) is a robust and low-cost method offering real-time visualization of processes. In this work, we developed an ERT-based method to characterize the rehydration behavior of milk protein concentrate (MPC) powders. Circular-type and linear configurations were used to achieve high resolution in the radial and axial directions, respectively. To evaluate the rehydration profile, MPC powders were reconstituted to 2.5% (wt/wt) total solids at room temperature, and the rehydration behavior of the MPC powders [MPC with 85% protein (MPC85) and milk protein isolate with 90% protein (MPI90)] was monitored for a dissolution time of 30 min using the ERT system. The MPC powders were characterized in terms of overall mean conductivity, area under the mean conductivity curve, slope at a dissolution time of 3 min, and the relative dissolution index. Additionally, the focus beam reflectance measurement (FBRM) was used as a reference method to follow rehydration characteristics. Particle count changes from the FBRM measurements showed that MPI90 had higher larger particle counts and more resistance to dispersing in water. As the dissolution time proceeded, mineral ions and proteins were released and consequently increased the overall conductivity, confirming the transfer of water into MPC particles. At lower protein contents, the particle dispersion rate was higher and an increase in overall mean conductivity was observed, indicating better powder dissolution. Both configurations were able to effectively monitor differences in the dissolution behavior of MPC powders. In the ERT circular configuration, MPC85 and MPI90 showed maximum conductivity of 0.201 ± 0.006 and 0.162 ± 0.001 mS/cm, respectively. In the linear probe configuration, MPC85 and MPI90 showed maximum conductivity of 0.161 ± 0.001 and 0.136 ± 0.001 mS/cm, respectively, suggesting increasingly inhibited water transfer as the protein content of the powder increased. In this study, we demonstrated the capability of ERT using the circular and linear probe configurations to offer, in addition to qualitative tomographic images, reliable quantitative data by which to characterize the dissolution behavior of high-protein dairy powders.
电阻层析成像（ERT）是一种强大且低成本的方法，可实现对过程的实时可视化。在本研究中，我们开发了一种基于ERT的方法来表征浓缩乳清蛋白粉（MPC）的复水行为。分别采用圆形和线性配置在径向和轴向上实现高分辨率。为了评估复水曲线，将MPC粉末在室温下复溶至总固形物含量为2.5%（重量/重量），并使用ERT系统监测MPC粉末[蛋白质含量为85%的MPC（MPC85）和蛋白质含量为90%的乳清分离蛋白（MPI90）]在30分钟溶解时间内的复水行为。根据总体平均电导率、平均电导率曲线下的面积、3分钟溶解时间时的斜率以及相对溶解指数对MPC粉末进行表征。此外，聚焦光束反射测量（FBRM）被用作跟踪复水特性的参考方法。FBRM测量的颗粒计数变化表明，MPI90具有更高的大颗粒计数，并且在水中的分散阻力更大。随着溶解时间的推移，矿物质离子和蛋白质被释放，从而提高了总体电导率，证实了水向MPC颗粒的转移。在较低蛋白质含量下，颗粒分散速率较高，并且观察到总体平均电导率增加，表明粉末溶解更好。两种配置都能够有效监测MPC粉末溶解行为的差异。在ERT圆形配置中，MPC85和MPI90的最大电导率分别为0.201±0.006和0.162±0.001 mS/cm。在线性探头配置中，MPC85和MPI90的最大电导率分别为0.161±0.001和0.136±0.001 mS/cm，表明随着粉末蛋白质含量的增加，水的转移受到越来越大的抑制。在本研究中，我们证明了使用圆形和线性探头配置的ERT除了能够提供定性层析图像外，还能够提供可靠的定量数据，以表征高蛋白乳粉的溶解行为。
