November 20, 2012

SCIENCE - WHY BROCCOLI TURNS OLIVE GREEN?

"We’ve found that broccoli has an internal clock that starts ticking once the broccoli has steamed for seven minutes.  At this point, chemical changes begin to occur that cause an initial undesirable loss of color and texture.  This loss intensifies as cooking continues.  By nine minutes, the broccoli has become discolored and mushy and it begins to take on a sulfurous flavor.

This deterioration is due to two factors: heat and acid.  As broccoli is heated during cooking, chlorophyll begins to break down, resulting in a change of color and texture.  In addition, all vegetables contain acids that leach out during cooking and create an acidic environment, further contributing to the breakdown of the chlorophyll.  None of this is an issue as long as the steaming time does not exceed seven minutes.  We find that broccoli has the best texture, color, and flavor after steaming for just five minutes, which also happens to provide the cook with a decent cushion before this chemical reaction begins." 

From Best American Side Dishes from The Editors of Cook’s Illustrated.

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