what is the meaning of the last line, " the shock of its difference had its own kind of strong pewter taste?

Before they moved to Durham – and moved up in the world – Mam pretended to the fancy neighbours at the end of the street, in the big corner house, that they ate meat at least three times a week for dinner. The old dirtylaundry smell of boiled cabbage: to this day, he refused to eat cabbage, refused to buy it. And yet he liked what he saw here. It was distinct, everything had sharp outlines, the shock of its difference had its own kind of strong pewter taste.