We have two types of sauce we put on our sausages. Tomato Sauce (Australian - ketchup equivalent) and Barbecue Sauce (Australian - mix of ketchup and Worcestershire sauce). The Tomato sauce indicates it needs refrigeration but the Barbecue sauce (made by the same company) does not say this.
My question is Why does Tomato Sauce (ketchup) require refrigeration but Barbecue sauce (like Worcestershire sauce) does not?