Portobello Mushrooms

Portobello Mushrooms are the fully grown version of button mushrooms, with the cap allowed to open before harvesting.

To become a Portobello Mushroom, a White Button Mushroom (Agaricus Mushroom) first becomes -- well, a White Button Mushroom, then grows into a Cremini Mushroom (cap still closed), and medium sized, and then grows to its fullest size, with the cap opened up, at which point it is called "Portobello". The mushroom's cap can be up to 6 inches wide (15 cm). Some will have smooth caps, some will have caps that are slightly wrinkled: the slightly wrinkled ones have even more flavour.

Chestnut Mushrooms are also allowed to grow into larger sizes to be sold as "Portobellos"; these will have slightly flatter caps. Sometimes Portobellos are also called "Flat Chestnut Mushrooms" for this reason.

Being fully opened mushrooms, some moisture loss has started in the Portobello, which condenses its flavour and gives it more of a meat-like texture.

It's funny that in stores people will avoid button mushrooms that have any brown on them (indicating flavour starting to develop), while they will pay a hefty premium for fully brown Portobello Mushrooms with the fancy name.

Cooking Tips
Some recipes will you have clean out the caps by removing the gills. This is not really necessary. Recipes that have you do this are having you make more room for a stuffing to go in. If you do clean out the gills, toss the scrapings into a small container or freezer bag and freeze them until a use for them in cooking presents itself.

Some say to discard the stems, as they are tough. The stems do need to be cooked, as they are a bit too tough to eaten fresh, but they are lovely for cooking with. If the recipe doesn't have you chop them up and incorporate them into the stuffing or what you are making, wash them and toss them into the freezer as well.

See also main entry for mushrooms.

Equivalents
6 oz (170g) Portobello Mushroom caps, stems removed = 2 1/4 cups chopped coarsely

Storage
See main entry for mushrooms. Tip: if you do freeze Portobello caps, they won't come out suitable for use as caps for stuffing. Count on needing to chop them up and use as you would any mushroom that you incorporate into a dish.

History
Portobello Mushrooms became popular in the 1980s. Before that, growers couldn't sell mushrooms when they got this mature, so they had to simply toss them in the compost heap. Everybody wanted the perfect looking little white mushrooms. Now, they pay extra for mushrooms that they would have looked at and discarded as "bad".

Language Notes
If you're confused about how the name should actually be spelled, join the club; everyone else is, too. The reason is that the name doesn't really exist. It's not an Italian name. Mushroom marketers just made it up, and everyone selling the mushrooms either got mixed up over whether o's or a's should be used in the name, and if so where, or some people selling the mushrooms just liked their mushroom's name pronounced a little differently.

Variations include:

Portobello
Portobella
Portabella
Portabello

For the record, it appears that "Portobello" was the original name invented.

Also called: Flat Chestnut Mushrooms Agaricus bisporus var. brunnescens (Scientific Name) Champignon Portobello (French)