I would say thats plenty, if you think about it some of those activities might take 15-20 mins so I'd say thats fine. If you have too many the party will go all day We went to a cooking party at a party place and all they did was the cookies.

If you want a food related game for prizes you could do a "Guess the food" game, have some tinned spaghetti in a bowl and they can feel it and see what it is, or some grapes or even chopped potato. Do it in another room so that they can't tell the other kids and the others can't see, but whoever gets the most right wins.