Do not add pesto over the hot stovetop. Especially when basil involves, basil turns black in color if done so. This poblano pesto is already prepared by roasting peppers, so I did not find any color change while adding it or while reheating. At the same time do not cook pasta after adding pesto sauce. Pesto with basil changes the color and texture if heated. Switch off the flame, add cooked pasta and finally add the sauce. Smear nicely and serve with favorite garnishing.