How to prevent chicken from having a chalky texture? Even after brining, filleting and cooking to perfect temperature (68 to 71 c) my chicken texture (whole and breast) sometimes comes chalky. Mind you, the chicken can still be juicy while being chalky. Here is a picture:



I have tried different combinations of brining solutions and cooking oils - nothing seems to give a consistent result of juicy, smooth textured chicken:



Mind you, this is not a duplicate of "why my chicken is dry" because many times I can get a moist but chalky chicken.
Your temperature of 68 to 71 Celsius is very high for white meat. This is what makes the mini clumps in the breast you perceive as "chalky". If you cook it to a lower temperature, you will not have this effect, 60 to 65 Celsius makes "medium" doneness chicken meat. 

Note that food safety is a separate consideration, chicken is considered safe starting at 73 Celsius (https://www.foodsafety.gov/keep/charts/mintemp.html). So you are lowering the temperature at your own risk.