An initial brightening of the green color is observed during the early heating of asparagus. The bright green color is attributed to removal of air around the ®ne hairs on the surface of asparagus spears and the expulsion of air between the cells that lead to a change in the surface re¯ecting properties (Woolfe, 1979). Further heating caused the color of asparagus spears to change from bright green to olive-brown which is attributed to the pheophytinization (Francis, 1985).