Possible Clues:

• Liquid nitrogen, for instance
• Substance used to produce very low temperatures
• Keen to get type of melon in freezer
• React to onions and melon in freezer
• One making cold call, having zero information
• Proclaim information about zero -- it's freezing stuff
• Liquid used as a refrigerant
• Substance used for obtaining low temperatures
• Sob before taking round information on refrigerant
• Announce sale of kind of melon that's used in freezing mixture