Celebrity chef Peter Blakeway said if everyone could cook properly there would be no need to buy processed food.
Unfortunately, it was hard to tell what was contained in food unless it was cooked from raw materials, he said.
"A carrot doesn't need a list of ingredients, it is a carrot. From my point of view, it is all about cooking and we have let down a few generations by not teaching them how to cook."
People needed to revisit what they did with food by cooking from fresh, local ingredients and the theory that processed food saved time was wrong, he said.