Mrs B makes marmalade

The local green grocer has a small supply of Seville oranges. Mrs B has, as usual, bought some and is making marmalade today. Breakfast is incomplete without marmalade.
I am mystified by some of the ingredients listed on a jar of commercially produced marmalade that we have: acidity regulator, plain caramel and calcium chloride. And I thought the stuff was oranges, sugar and lemon juice.