Is there a limit to how much MPC can be added to yogurt?

Yes. When MPC is utilized at higher levels in yogurt formulas, the casein starts to impart a gritty, grainy texture to the yogurt gel. This is not a significant problem with regular yogurts here in the USA or in Europe, as it is highly unlikely that a manufacturer would add MPC to their yogurt milk in high enough levels to impact the smoothness of the yogurt gel. It becomes a problem for yogurt manufacturers in those countries that have limited milk supplies and need to use higher quantities of MPC to extend out their milk solids for yogurt manufacture. Milk is in short supply in regions such as Asia, the Middle East, Northern Africa, tropical locales like the Philippines, parts of South America, and even Canada to some extent. In countries with limited milk supplies, where manufacturers would use MPC as if it was fluid milk by diluting MPC dispersions back to fluid milk composition, yogurt gel textures could start to become grainy as the usage level of MPC increases in the yogurt milk. Even so, many of these countries do not experience any major problems with gel texture in regular yogurts. For those that do experience problems, blends are available that include both MPC and WPC. The MPC provides gel strength/stability and a realistic gel texture. WPC tends to help smooth out the yogurt gel. Such blends of MPC and WPC would allow a yogurt manufacturer in milk-deprived regions to advance from replacing 20% of skim milk solids with MPC or WPC to perhaps, 50% replacement of skim solids with a MPC/WPC blend without a significant loss in product quality.