CPG Sec. 515.500 Barley Sugar - Definition, and Barley Sugar Candy
Available information indicates that when sugar is heated to 160 degrees C. (320 degrees F.) it melts without loss in weight, and congeals on cooling, to a transparent amorphous yellowish mass which becomes gradually opaque on the surface from the formation of minute crystals, and that the resulting product is sometimes referred to as barley sugar. A second source of information states that when rock candy is heated to 185 degrees C. (365 degrees F.), it melts into a viscid, liquid, which on being suddenly cooled forms a transparent mass called barley sugar.
It is apparent that the term barley sugar is being loosely applied to a product which is not now prepared even in part from barley. We doubt that the term has a derived meaning which would make it understandable to the purchaser, although it may be understood by sugar technologists.
We are therefore inclined to discourage the use of the terms barley sugar and barley sugar candy as it is proposed to use them, since they appear to be ambiguous. However, we have made no investigation of consumer understanding of these terms and can advise interested persons only that the responsibility for their use rests upon the manufacturer of the products.