Why is white asparagus white? What is white asparagus? The answer is really rather simple and takes you back to your early science classes in primary school. Remember those lessons about chlorophyll and photosynthesis? You never thought they’d come in handy, huh? Well, think again!
White asparagus is asparagus that has been deprived of sunlight. The simplified explanation: this prevents photosynthesis taking place, and therefore, stops the production of chlorophyll, which is responsible for plants being green in colour. So the asparagus remains white. This is the simplified explanation, see excerpt below.
As the asparagus shoots grow, they are continuously covered with soil/compost to keep them in the dark. This labour intensive part of growing white asparagus is reflected in its price. I pay about £1 per stalk, sometimes more.
When is white asparagus in season? White asparagus can be found from April to June and the best ones, here in the UK, are always to be found at farmers’ markets.
What do white asparagus taste like? They are most certainly very mild, almost bland, a touch sweet like their green cousins, but also with a hint of bitter.
How to cook white asparagus? White asparagus are woodier and tougher than green asparagus and will need peeling. The best way to do that is to use a vegetable peeler and very lightly peel off the outer layer, as thinly as you can. Remove the lower, thick half, which can then be used in stocks. You can steam, sauté or grill white asparagus. My favourite way with them is cooked in a little butter, cooled, then tossed in salad, along with another springtime favourite – wild garlic leaves.
And just like their green cousins, they are used in desserts too!
Great explanation for this no sunlight, no chlorophyll conundrum:
Dan Metcalfe, from Ask a Biologist.
“The organelles which contain chlorophyll, called plastids, need light in order to complete the synthesis and activation of chlorophyll, which together with other pigments then absorb most wavelengths of light excepting those in the green wave bands – this results in the light reflected from leaves being relatively enriched in green wavelengths and therefore appear to be green to us.
In the absence of chlorophyll or another pigment light reflected off the surface of a leaf is not enriched in any particular wavelengths and thus appears to be white Or nearly so (often cream or pale yellow). Leaves can appear white when they lack a gene to synthesise the chlorophyll pigment, which may be apparent only in part of a so-called variegated leaf. Leaf miners which eat the chlorophyll-containing tissues inside a leaf may also leave white trails across the surface of a leaf. Lack of critical nutrients may prevent a leaf from making chlorophyll, which can result in a leaf with yellow or white blotches on it, known as chlorosis. As you mention in the question, keeping a plant in the dark will also prevent the leaves from turning green.”
So now, you really know!