Possible Clues:

• Money returned - cheese needs it to curdle
• Note how this turns up for cheese
• Might one stomach getting this up to make him sound high?
• For something sweet from the stomach
• Cheese-making curdler
• Cheese curdling agent
• Substance used in cheese making
• Said bird, fish-catcher, had apple
• Money back due to substance in milk product
• Curdling substance