The very first thing, I remembered learn from science classes is about matter -how we have solid, liquid and gas state. The arrangement of particle and the kinetic energy that each matter possess.
The title 'liquid art' refer to the use of liquid to create art. We can do many things to food liquid if it can be made into solid food.
For example, chocolate. Came from cocoa bean, chocolate have an amazing properties - melt when heated making it a perfect food liquid to design a food art. And it would always make a good desert for most of us - the chocolate fan.
Making a food art with chocolate could just be melting the chocolate bar (meant for cooking), smear it on the plate to create some design. Or dippping strawberry or pretzel into the chocolate batch and let dry. It could also be placed into a mould and made into a shape that you like.
Becareful not to over-dilute the chocolate bar. Otherwise, it will take time to solidify. Remember to take picture before it is gone.