Pulling taffy was a favorite party activity in our grandparents' time. Stretching the candy is what gives it its satiny texture.
In a large saucepan, combine the sugar, corn syrup, water, salt, and glycerine. Mix well with a wooden spoon. Cook over medium heat, stirring occasionally. Remove from the heat when a candy thermometer inserted into the mixture reads 255 degrees. Stir in the butter and food coloring. Pour into a greased flat pan to cool.
Using a metal spatula, fold over the candy edges to keep them from hardening. When the mixture is cool enough to handle, brush on the citrus juice, and it's ready to pull. Butter your hands well and stretch the taffy until it is elastic, about 5 minutes. Pull into a long rope and cut into bite-size pieces.