This work evaluated the impact of the calcium reduction level (0 %, 10 % and 40 %) of micellar casein concentrates (MCC) and the presence of sugar and fat, on the fouling of the UHT plant and the heat stability of neutral high protein (14 %) beverages. The assessment of the heat stability was done using UHT pilot scale tubular heat exchanger (142 °C, few seconds). The aim of this study is to identify a casein modified structure suitable for the development of high protein beverages with acceptable functional properties and less fouling of the UHT plant. Our results showed that increasing the calcium reduction degree of MCC from 0 % to 40 % has drastically decreased the fouling rate by 4-fold for casein-based beverages without sugar and fat. In addition, the results of SDS-PAGE, HPLC and ICP-MS revealed that increasing the calcium reduction degree from 0 % to 40 % induced an increase of the mineral fraction from 13 % to 70 % and a decrease of the protein fraction from 77 % to 7 % in the fouling deposits. The HPLC results also showed that the increase of the calcium reduction appears to limit the deposition to dissociated protein from the micelles, in particular β-CN. Our results showed that the addition of sugar and fat induced an increase of the fouling deposition for all drinks and this increase was mostly linked to the increase of the protein deposition. Our results also showed that the calcium reduction degree doesn’t have an impact on the particle size distribution. However, aggregates started to appear in the simple and complex beverages with the increase of the storage period. Overall, our results showed that the calcium reduction of MCC powders seems to be a good option to manufacture casein-based RTD beverages at high protein concentrations and to reduce the fouling of the UHT plant.