So the top line (40° di puro grano /  40° OF PURE WHEAT), which marks already a genuineness (PURE WHEAT) points up on an identity by semantic similarity.  

The vodka heats (the 40° and the flame do it ): an identity by spatial contiguity. There is even an identity by temporal contiguity (the vodka is produced by the wheat, which is a visual confirmation of the top line (40° OF PURE WHEAT).  In addition,  the red colour of the background and the heat rash of the vodka both propose a further semantic identity on red and fire. It is present even a metonymy made by the flame of wheat that comes out from the neck of the bottle (the matter for the object ), and the metonymy is a figure of identity for semantic similarity.