I wanted to pin this photo to see a professional set up for using lighting gels. Here there is technology used including a stand with the lighting gel over the light which is being bounced onto a stand with lines in to created shadow on the model.
How to use Backlighting for Food Photography (Click It Up a Notch)
Food Photography: Backlighting is one of those beautiful lighting techniques that is so easy to achieve, you’ll wonder why you didn’t try it before. All you really need are some good windows with some nice light.
Home photo studios: how to shoot pro-quality portraits with a basic studio kit
These different types of lighting create different gradients and colours of light giving an image more meaning and depth. The way the light is enables the image to be more interesting and direct to what you want for your shoot.