crinkle -
make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in; "The dress got wrinkled"; "crease the paper like this to make a crane"
fold up,
fold,
turn up incorporate a food ingredient into a mixture by repeatedly turning it over without stirring or beating; "Fold the egg whites into the batter"
fold up,
fold incorporate a food ingredient into a mixture by repeatedly turning it over without stirring or beating; "Fold the egg whites into the batter"