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Mushrooms, cultivated and wild

(large white, button, chestnut, portobello, oyster, enoki, shiitake, porcini (ceps, boletus) chanterelles, morels)

Mushrooms, or edible fungi, come in lots of different forms, each with its own colour, scent, texture and flavour. Wild chanterelles, for instance, have an almost apricot-like perfume, while shitake can have a smoky presence. Large black portabello and field mushrooms are distinctly meaty. Chestnut mushrooms have more of that woodland taste than the white button sort. But, taken as a family, they share certain characteristics. They taste earthy and savoury, and are one of a few plant foods capable of producing the rich flavours found in meats and cheeses. Japanese people refer to this quality as ‘umami’, and consider it to be the fifth component of taste along with sour, sweet, salty and bitter. Mushrooms have this rich savoury flavour because they contain glutamic acid, a naturally occurring flavour enhancer – not to be confused with the synthetically made food additive, monosodium glutamate (MSG) – along with other natural flavour enhancers. When mushrooms are dried, these natural flavour enhancers are intensified, which is why dried mushrooms pack more punch than their fresh equivalents.

Whatever type of mushrooms you are buying, the same rule applies: look for firm, dry heads and avoid any that look wet or shiny as this is a sign that they are starting to decompose.

Things to do with mushrooms

• A basic liquidized soup made with fresh mushrooms, onion and stock is transformed by the inclusion of a couple of soaked, dried porcini before blending.

• Fill large flat mushroom heads with herby butter (try thyme or tarragon), top with breadcrumbs and bake or grill until they are soft below and crunchy on top.

• Sauté mushrooms with strips of bacon or pancetta, some fresh sage (if you have it), season with black pepper and sea salt, and add thick cream and chopped parsley: an instant sauce for spelt, pearl barley or pasta.

• Brush toasted sourdough bread with olive oil and a thin layer of Dijon mustard, then top with a pile of pan-fried wild or cultivated mushrooms, tossed with chopped tarragon, and a fried egg for a quick, filling supper.

• You can turn the remains of a beef stew into a cheat’s stroganoff by stirring in sautéed, sliced mushrooms and soured cream. A dusting of chopped dill adds sparkle.

Are mushrooms good for me?

Mushrooms may not look that promising, but they have many nutritional strengths. They are a good source of soluble fibre, which slows down the speed at which sugar is released into the bloodstream, and B vitamins, which provide energy and support brain function. While it used to be thought that vitamin D was not found in plant foods, a plant sterol – ergosterol – has been identified in mushrooms, which converts to vitamin D when exposed to light. Vitamin D is increasingly being recognized as protective against a wide range of diseases and it is thought that many British and Irish people do not get enough of this for optimum health. For vegetarians especially, mushrooms are a welcome source of vitamin D.

Mushrooms are also a good source of key minerals such as copper, which helps blood cell production, and selenium, which is thought to be protective against certain cancers. Some research suggests that the fatty acids in mushrooms, particularly conjugated linoleic acid, may inhibit breast cancer cell growth. Other research has suggested that certain mushrooms, such as shitake, have immune-modulating effects; that is, they help regulate and strengthen the immune system.

Cultivated mushrooms are usually treated with fungicides while they are growing. Use of insecticides and chemical disinfectants, such as chlorine, is also routine for sterilizing mushroom sheds between growing cycles. If you would rather that your mushrooms weren’t grown this way, choose organic. Organic growers are not allowed to use these chemicals and their mushroom sheds must be steam-cleaned.

Eating mushrooms collected from the wild is a risky business as it is quite easy to confuse edible and poisonous types. However enthusiastic you are about foraging, it is vital that any you intend to eat have been correctly identified by a reliable, experienced person – a poisonous one can kill you.

How are mushrooms grown?

The cultivated mushrooms we eat are nearly all grown in Britain and Ireland. They are cultivated in indoor environments that mimic the natural stages of mushroom growth. Many types of mushroom can be grown this way, not only the familiar white- and brown-capped types such as button and chestnut, but types that are often thought of as wild, such as oyster mushrooms and shitake. First a growing medium, or compost, is prepared, typically a mixture of straw, gypsum (a mineral used to make plaster) and poultry litter. Poultry litter is a euphemism for bedding cleaned up from the floor of indoor poultry production units. It consists of straw, poultry droppings (manure), feathers and possibly uneaten feed. Compost for growing organic mushrooms is mainly made from organic straw, but sometimes sawdust or woodchips are used. It can also contain manure from organic, but not intensively farmed, livestock.

Once mixed, the compost is allowed to decompose naturally for a time, then it is pasteurized to kill off any potentially dangerous bacteria or moulds. This method produces the crumbly dark compost that you see clinging to the base of mushroom stems.

The compost is then inoculated with mushroom spores (mycelia) and put in bags, or spread out on trays, blocks and shelves, in hot, humid, dark sheds. This encourages the spores to multiply throughout the compost. When the spores have thoroughly colonized the compost, it is covered with a layer of ‘casing’, usually peat mixed with sugar beet lime, and the temperature is reduced to encourage the mushrooms to fruit. The mushrooms come through in flushes, and are harvested by hand in low light. Some types of mushroom can also be grown on inoculated logs.

Wild mushroom spores spread underground in woods, then, given the right weather conditions, they ‘fruit’ or produce edible mushrooms in among vegetation and decaying leaf mould. Wild mushrooms are harvested by foragers, usually for cooking at home, although some semi-professional foragers supply them to shops and restaurants.

Are mushrooms a green choice?

Commercial mushroom growing, both conventional and organic, is a major user of peat and this is helping to drive the depletion of peat bogs in Britain and Ireland. Peat bogs, which take centuries to form, provide a very special and rare habitat for plants and animals. They also act as very effective ‘carbon sinks’, storing carbon dioxide below ground. When peat is drained and dug up, this escapes into the atmosphere and speeds up global warming. Some mushroom growers are trying to reduce their dependency on peat and looking at greener alternatives, such as fine waste from coal mines and quarries.

Mushroom-growing sheds and buildings are very energy-intensive because they need to be heated to high temperatures for much of the year. This makes them high users of non-renewable fossil fuels. This is to some extent offset by the fact that most of the mushrooms we eat are cultivated in the UK and Ireland, so no energy is involved in transporting them from abroad. Some producers are trying out alternative types of fuel that may be more environmentally friendly, such as old mushroom compost.

COMPETITION IN THE WOODS

With all our dark, mossy woods, Britain and Ireland make ideal territory for mushroom foragers, so it is perhaps surprising that wild mushrooms have not featured greatly in our traditional food repertoire. Instead, we have been largely indifferent to the natural bounty of fungi on our doorsteps, unlike people in continental Europe where wild fungi are widely valued as a free food source and figure prominently in many popular recipes.

Until recently, most of our wild mushrooms went unpicked, so any keen foragers and mushroom enthusiasts scouring the woods for species such as chanterelles and boletus (ceps, porcini) had expanses of woodland more or less to themselves. Much of what they harvested was exported to Europe, or sold to upmarket restaurants, and there was little home consumption. All that has changed with the arrival of migrants from eastern Europe, notably Poland, whose love for fungi in all forms does not allow them to leave nature’s bounty rotting untouched. Nowadays, by all accounts, our woods are on the picker’s map. Set out into the woods now with your mushroom knife and basket and chances are you’ll have company.

Where and when should I buy mushrooms?

Fresh mushrooms cultivated in the UK and Ireland are available year round. The best season for picking the most popular wild mushrooms species is late summer and autumn. Dried porcini – the most aromatic type of dried mushroom – are widely available in delicatessens and supermarkets. Asian supermarkets stock the best selection of dried oriental mushroom varieties.

Will mushrooms break the bank?

Cultivated mushrooms are blissfully cheap. Mushroom soup and mushroom risotto are some of the most inexpensive dishes you can make. Mushrooms on toast, fried with a little garlic and tossed with parsley, can make a surprisingly substantial main course. Mushrooms can also be used in quantity to spin out more expensive ingredients. For instance, you can considerably reduce the amount of meat in a recipe for beef stroganoff, and up the amount of mushrooms, without spoiling the dish.

Dried mushrooms, especially porcini, have a particularly intense flavour and aroma that can be used to perfume a dish. You get an astonishing amount of flavour from a very small pack. Water left over from soaking wild mushrooms should never be thrown away, but added to the dish to intensify its taste.

Fresh wild mushrooms are either free or extremely expensive, depending on whether you have picked them yourself.