On Food and Cooking

In Europe, the even more labor-intensive
white version, blanched by being covered with
soil and cut from underground, has been
popular since the 18th century. It has a more
delicate aroma than green asparagus (which is
rich in dimethyl sulfide and other sulfur
volatiles), and some bitterness toward the
stem end. Exposed to light after harvest, white
asparagus will turn yellow or red. Purple
asparagus varieties are colored with
anthocyanins, whose color generally fades
during cooking, leaving the green of the
chlorophyll.
Harvested early and fresh from the soil,
asparagus is very juicy and noticeably sweet
(perhaps 4% sugar). As the season progresses,
the rhizomes become depleted of stored
energy, and sugar levels in the shoots decline.
Once harvested, the actively growing shoot
continues to consume its sugars, and does so
more rapidly than any other common
vegetable. Its flavor flattens out; it loses its