# Flammulina filiformis

Flammulina filiformis, commonly called enoki mushroom, is a species of edible agaric (gilled mushroom) in the family Physalacriaceae. It is widely cultivated in East Asia, and well known for its role in Japanese and Chinese cuisine. Until recently, the species was considered to be conspecific with the European Flammulina velutipes, but DNA sequencing has shown that the two are distinct.

## Etymology

In Japanese, the mushroom is known as enoki-take or enoki-dake, both meaning "hackberry mushroom". This is because it is often found growing at the base of hackberry (enoki) trees.
In Mandarin Chinese, the mushroom is called jīnzhēngū (金針菇 "gold needle mushroom") or jīngū (金菇 "gold mushroom").
In Korean, it is called paengi beoseot (팽이버섯) which means "mushroom planted near catalpa". In Vietnamese it is known as nấm kim châm. In India it is called futu.

## Description

Basidiocarps are agaricoid and grow in clusters. Individual fruit bodies are up to 50 millimetres (2 inches) tall, the cap convex at first, becoming flat when expanded, up to 45 mm (1+3⁄4 in) across. The cap surface is smooth, viscid when damp, ochraceous yellow to yellow-brown. The lamellae (gills) are cream to yellowish white. The stipe (stem) is smooth, pale yellow at the apex, yellow-brown to dark brown towards the base, and lacking a ring. The spore print is white, the spores (under a microscope) smooth, inamyloid, ellipsoid to cylindrical, c. 5 to 7 by 3 to 3.5μm.
There is a significant difference in appearance between wild and cultivated basidiocarps. Cultivated enokitake are not exposed to light, resulting in white or pallid fruit bodies with long stipes and small caps.

## Taxonomy

Flammulina filiformis was originally described from China in 2015 as a variety of F. velutipes, based on internal transcribed spacer sequences. Further molecular research using a combination of different sequences has shown that F. filiformis and F. velutipes are distinct and should be recognized as separate species.

## Distribution and habitat

The fungus is found on dead wood of Betula platyphylla, Broussonetia papyrifera, Dipentodon sinicus, Neolitsea sp., Salix spp, and other broad-leaved trees. It grows naturally in China, Korea, and Japan.

## Nutritional profile

Enoki mushrooms are 88% water, 8% carbohydrates, 3% protein, and contain negligible fat (table). In a 100-gram reference serving, enoki mushrooms provide 153 kilojoules (37 kilocalories) of food energy and are an excellent source (20% or more of the Daily Value) of the B vitamins, thiamine, niacin, and pantothenic acid, while supplying moderate amounts of riboflavin, folate, and phosphorus (table).

### Potential health benefits

The nutritional value of F. filiformis has long been recognised, which makes them an object of interest in current research. F. filiformis is a rich source for carbohydrates, proteins and unsaturated fatty acids as well as several noteworthy micronutrients and dietary fiber.
While its nutritional value and culinary applications are well established, recent studies have begun exploring its potential medicinal properties in greater depth. Several bioactive molecules from various chemical classes have been isolated from F. filiformis extracts, showing promising potential for future applications as nutraceuticals or dietary supplements. Moreover, bioactive polysaccharides derived from F. filiformis have demonstrated to exhibit a broad spectrum of bioactivities, including anticancer, immunomodulatory, and anti-neurodegenerative effects. However, the precise mechanisms underlying these actions remain unclear and warrant further investigation in future research.
In conclusion, F. filiformis holds significant promise as both a functional food and a nutraceutical, and may serve as an interesting source of bioactive compounds for therapeutic and pharmaceutical purposes.

## Uses

F. filiformis has been cultivated in China since 800 AD. Commercial production in China was estimated at 1.57 million tonnes per annum in 2010, with Japan producing an additional 140,000 tonnes per annum. The fungus can be cultivated on a range of simple, lignocellulosic substrates including sawdust, wheat straw, and paddy straw. Enokitake are typically grown in the dark, producing pallid fruitbodies having long and narrow stipes with undeveloped caps. Exposure to light results in more normal, short-stiped, colored fruitbodies.

### As food

The mushroom is widely eaten in East Asia. Cultivated F. filiformis is sold both fresh and canned. The fungus has a crisp texture and can be refrigerated for approximately one week. It is a common ingredient for soups, especially in East Asian cuisine, but can be used for salads and other dishes.
* In Korean jjigae (stew)
* In Korean bokkeum (stir-fry)
* In Japanese sukiyaki
* Grilled

### Improved storaging

F. filiformis extract can be added to whipped cream. It was observed that this measure helps to slow down the development of ice crystals, which would maintain the quality of whipped cream longer while storing it in a frozen state.

### Nutritionally improved meat products

F. filiformis are an object of interest in current research for their potential to enhance food products and animal feed by using the stem waste.
Studies indicate that the addition of F. filiformis stem waste powder to meat products can improve nutritional quality by increasing dietary fiber and ash content. This ingredient also enhances tenderness, inhibits lipid and protein oxidation, and extends shelf life, without negatively impacting the texture or flavor of the meat products.

### Feed additive for livestock

Natural feed additives become more important in livestock farming. Following this trend, F. filiformis was checked for livestock health and production efficiency improving properties. There are studies showing that the use of Enoki mushroom residue as a feed additive offers several benefits for livestock. It enhances antioxidant enzyme activity, and improves animal digestibility, hormone levels, and immunity.
The addition of mushroom residue in the livestock diet can reduce the feed cost and feed conversion ratio and enhance the meat quality, providing consumers with healthier and higher-quality meat products.

## Cultivation and harvest

The common way to cultivate F. filiformis is in a large-scale factory style. By using modern possibilities to mechanize processes, over 300'000 tons a year of F. filiformis can be harvested that way.

### Indoor cultivation

F. filiformis thrive in a warm, moist environment during the incubation phase, with substrate temperatures ranging from 18 to 25°C (64 to 77°F). F. filiformis need significantly cooler conditions to trigger fruiting. Pinning is triggered at temperatures ranging between 7 to 10°C (45 to 50°F), and the optimal temperature range for fruiting is 10 to 16°C (50 to 61°F). As with most fungi, F. filiformis also demand elevated humidity levels—95 to 100% during pinning and 85 to 95% during fruiting.
The ideal size to harvest enoki mushrooms is generally recommended to be about 2-4 inches in length. At that time, the cap of F. filiformis should still be tightly closed and the stem should be long and sturdy. If people grow enoki mushrooms at home, they can use a sharp knife or scissors to snip off the mushroom cluster at the base of the stem where it meets the growing medium. It's important to remove both the mushrooms and any remaining mycelium (the white, thread-like structures) from the growing medium during harvest. This helps prevent decaying, which could negatively impact future mushroom growth.

### Post-harvest handling

F. filiformis have thin, delicate stems that need to be handled with care to prevent damage. The following steps are for reference. First, gently brush off any dirt or substrate with a soft brush or a damp cloth. After cleaning, separate the mushroom clusters into individual stems for easier cooking and presentation.

### Storage

F. filiformis should be kept at temperatures between 7-10°C (44.6-50°F) for optimal freshness. For brief storage (fewer than 7 days), a temperature interval of 1-2°C (34-36°F) with 90-98% relative humidity is advised.

### Proneness to Listeria

F. filiformis have the potential to be contaminated with listeria monocytogenes, which is why disease control centers recommend cooking the mushroom upon consumption.
Singapore Food Agency advise people to do the following to ensure food security when consuming F. filiformis:
* Enoki mushrooms should never be eaten raw
* Instead, make sure to cook the mushrooms properly before eating them
* If there are cooking directions at hand, make sure to follow them
* Enoki mushrooms should be stored at cold temperatures to ensure a slower growth of microbes. This should be done even if the packaging is not opened yet
* Uncooked enoki mushroom should be stored separately to avoid cross-contamination