The marshmallow ingredients are listed by volume because that is the way the Chow recipe was written. I did use a small amount of food coloring in both the base and the marshmallow. It is totally optional/completely unnecessary. Had I not used it, the ice cream base would have been much less pink, and I really wanted it to be a nice strawberry pink when churned. I just put a bit of gel coloring into the base using a toothpick. It probably amounted to one or maybe two drops of liquid food coloring. I used about the same amount of green coloring in the mallow. As you can see from the photographs, the mallow doesn't really read as green, but there is enough of a tint to keep it from being stark white.