Chestnuts are available in a variety of forms: as whole fresh nuts either in shells or with the shell removed; as a frozen nut peeled and ready to use; as a canned nut, dried, peeled and roasted; as a whole nut preserved in a sweet syrup known as candied Chestnuts or marrons glacés; as a puree; and as a paste. Chestnuts are also available ground into chestnut flour for baking, however the flour has a strong nutty flavor so it may be best to mix it with other varieties of flour for a milder tasting result. Chestnuts should not be consumed raw or fresh because of the tannic acid contained in each nut, which causes stomach discomfort. Roasting, braising or boiling the nuts is required to make the Chestnut edible. When selecting Chestnuts in the shell, choose those that are heavy for their weight, are glossy in appearance and are free of blemishes. There should be no musty or earthy mildew aroma coming from the Chestnuts, which would indicate they have been exposed to excessive moisture. Similarly, check the Chestnuts for a rattling of loose nuts in the shell or a cracking of the shell indicating they have dried out too much for consumption.
To store fresh Chestnuts, make sure they have been removed from their prickly casing and placed in a cool dry area away from excessive heat or moisture to be consumed within 6 to 8 days. Nuts still in the shell can be kept refrigerated and stored for 3 to 4 weeks in a loosely closed or perforated bag allowing only small amounts of air to circulate around the nuts to keep them from becoming damp or moldy. Nuts that have been shelled or cooked can be refrigerated or frozen. If refrigerated, use within several days or if frozen, consume within 7 to 9 months. Dried Chestnuts should be kept in an airtight container away from heat. Similar to other nuts, dried Chestnuts can be kept for several months at room temperatures or if frozen, they should be used within six months, being cautious not to expose them to excessive moisture. Fresh Chestnuts that have not been cooked can also be stored in the refrigerator, however they are best preserved if placed in dry sand or peat moss to seperate the nuts. Make sure the sand has been dried and contains a very low amount of moisture. Nuts are then best kept in a temperature range of 25ºF (-4ºC) to 30ºF (-1ºC).
To roast Chestnuts, begin by using a kitchen knife or a Chestnut knife or a slitting tool to score and cut the shell with either a straight slit or an "X" slit where it looks like the shell bulges outward. This will allow steam to be released rather than building up and exploding the shell as it roasts. Place the Chestnuts in a dish or pan that will allow the water to fully cover the chestnuts and let them soak for 30 minutes to an hour before roasting. Remove the nuts from the water and pat dry. If oven roasting, place the nuts in a roasting pan or baking sheet and roast at a temperature of 400º to 425ºF for 20 to 25 minutes or until the shells begin to curl where they were slit-scored. If roasting on the stovetop or over coals, place the nuts in a Chestnut pan containing a bottom with open holes and use a low to medium heat setting if on a stovetop or place the pan approximately 6 inches above the heat if using coals. It is often suggested that the pan be covered, depending on the amount of heat applied to the roasting, but it may be a matter of preference depending on the procedure. When prepared over a stovetop or coals, heat for 10 to 20 minutes shaking the nuts occassionally to disperse the heat evenly, making sure that the Chestnuts don't burn. When finished roasting, allow the nuts to cool either openly or in an old towel. If wrapped in a towel, the protection of the cloth can be used to apply pressure to the shell so it cracks while the nut is hot. If necessary for removing the shell or if cooled without a towel, the nut can also be removed from the shell by making a single score/cut fully around the middle of the shell. Although the nut may stick to the skin, the moisture from soaking and the heat should have adequately separated the skin from the shell to remove the nut easily.
Braising Chestnuts (marrons braisés) is a common preparation method in France where the nuts accompany many poultry dishes. Use the same procedure for roasting when preparing the nuts, by scoring the outer shell with an "X". Place the nuts on a baking sheet or pan and bake at 400ºF for 12 minutes. Remove the nuts from the oven and when not too hot to handle, peel the shell and skin from the Chestnut. The Chestnuts are then ready to be added to a skillet containing a sautéed base stock of choice such as salt pork, shallots, and wine where the nuts will be added and cooked on simmer until the liquid stock cooks away and the Chestnuts are tender. While roasting of Chestnuts typically keeps the texture firm as the heat dries the nut, boiling Chestnuts softens the texture as moisture is added to the nut. If firm Chestnuts are to be used as an ingredient in a baked foods, boil the nuts to remove the shell and skin. Fill a pan with just enough water to cover the Chestnuts. Allow them to reach boiling and then simmer for 3 to 4 minutes, removing the nuts so the shell and skin can be peeled away. The Chestnuts can then be added to foods for continued baking. To boil the Chestnut for mashing, place the shelled nuts in a pot with enough water just to cover all of the Chestnuts. Allow the water to reach a boiling temperature and then simmer the nuts for approximately 20 minutes. After they have cooked and while they are still hot or warm, the skin should peel easily away from the nut. They can then be mashed or pureed for use with poultry and meat dishes. The desired consistency of mashed or pureed Chestnuts can be altered with a broth or milk and seasoned with salt, pepper or various herbs before serving.
A Chestnut contains 1 gram of fat, the lowest fat content of all nuts but are high in starch, containing more starch than a common potato. Water Chestnuts are not the same as tree Chestnuts. Water Chestnuts grow as an aquatic plant with a bulb containing a meaty flesh that is easily sliced and has some similarity in texture and sliced appearance to a tree Chestnut.
Although sizes vary and will affect the amount, generally 1 pound of fresh medium size Chestnuts shelled (approximately 75 Chestnuts) equals: