Shiitake mushrooms are a popular edible mushroom used frequently in Asian cuisine. They are highly nutritious and provide many health benefits. However, while the caps of shiitake mushrooms are edible and delicious, the stems are tough and woody and typically discarded. There are a few key reasons why shiitake mushroom stems are not usually eaten.
The Texture is Too Tough
The main reason shiitake mushroom stems are not eaten is that they have an extremely tough, woody texture that is unpalatable when raw or cooked. The caps of the mushrooms have a tender, slightly chewy texture when cooked that is perfect for soups, stir fries, etc. But the stems are fibrous and stringy even after thorough cooking. Some describe the texture like eating a piece of wood or cork. This makes the stems unenjoyable to eat for most people.
Unpleasant Flavor
In addition to the undesirable texture, shiitake mushroom stems have a very mild, woody flavor. While the caps have a rich, earthy, meaty umami flavor, the stems lack robust flavor. When cooked, they tend to be bland with a hint of bitterness. The unpleasant texture combined with very little flavor payoff makes the stems unappetizing to consume.
High Concentration of Undesirable Compounds
Research has found the stems of shiitake mushrooms contain higher amounts of certain compounds that may cause digestive upset if consumed in excess. The stems contain high concentrations of chitin, a type of fiber humans cannot digest. Chitin can potentially cause gastrointestinal irritation, diarrhea, bloating, and cramping if large amounts are eaten. The stems also contain eritadenine, which can interfere with vitamin B6 absorption. Consuming the mushroom caps provides health benefits without the same risks of consuming high amounts of these compounds found in the stems.
Nutritional Value Lower in Stems
The caps of shiitake mushrooms are packed with nutrition, while the stems contain lower, less beneficial nutrient levels. The caps are rich sources of B vitamins like riboflavin, niacin, and folate. They also provide essential minerals like selenium, potassium, and zinc. Research shows the stems contain lower, less optimal amounts of many key nutrients compared to the caps.
How Shiitake Mushrooms Grow
To understand why the stem is less desirable, it helps to know how shiitake mushrooms grow. Shiitake mushroom spores germinate and form miles of underground root-like strands called mycelium. The stem acts like the root structure, anchoring the mushroom in place and absorbing nutrients from the mycelium network to feed the developing cap. As a root-like structure, the stem transports nutrients but does not store many itself, which explains its woodier texture and lesser nutritional value.
Preparation Methods to Improve Texture
While most of the stem is generally discarded, there are preparation methods that can help make the texture more palatable:
- Cutting the stems into very thin slices across the grain – This cuts through the tough fiber strands to make a more tender, delicate texture.
- Fermenting the stems – Fermenting helps break down the indigestible components like chitin, improving texture.
- Dehydrating the stems – Drying them out makes them crunchier with less fibrousness.
- Powdering/grinding the stems – Grinding them into a powder incorporates them into dishes without the unpleasant chewiness.
These preparation methods can make the texture less stringy. However, the flavors and nutritional profile will still differ greatly from the caps.
How to Separate the Stems
When preparing shiitake mushrooms, it’s important to know how to properly remove the stems. Here is a simple method:
- Start by gently grasping the cap in one hand and the stem in the other hand.
- Slowly twist the stem while providing counter pressure on the cap. The stem should detach cleanly where it meets the bottom of the cap.
- Trim off any darker portions of the stem where it was attached using a paring knife. Discard the stems.
- If any darker stem residue remains on the mushroom caps, gently scrape it off with the knife.
- The caps are now ready to use in cooking recipes.
With a simple twist and pull motion, the undesirable stem can be easily removed from the nutritious cap.
Popular Uses for the Stems
While the stems are not eaten directly in large quantities, they can be used in some unique ways to provide flavour and nutrition:
- Add to stocks and broths – Simmering the stems makes a flavourful mushroom broth.
- Blend into sauces and gravies – The chopped stems lend an umami flavor when blended into pan sauces.
- Powder as an addition to rubs and spice blends – Dehydrated, ground stems provide a savory flavor boost.
- Use to make infused vinegars, oils, and spirits – Steep stems in vinegar, oils or alcohols to extract flavor.
- Include in mushroom compost – The stems can be broken down in garden compost piles.
While not suitable to eat whole in large amounts, the stems can be a useful ingredient when used creatively in small quantities.
Nutritional Comparison of Caps and Stems
Here is a nutritional comparison between 100 grams of raw shiitake mushroom caps vs. stems:
| Nutrient | Caps (100g) | Stems (100g) |
|---|---|---|
| Calories | 34 | 28 |
| Protein | 2.24g | 1.72g |
| Fat | 0.49g | 0.21g |
| Carbs | 6.97g | 6.15g |
| Fiber | 1.9g | 2.4g |
| Riboflavin | 0.537mg | 0.074mg |
| Niacin | 4.789mg | 1.333mg |
| Folate | 17μg | 5μg |
| Vitamin B5 | 1.387mg | 0.606mg |
| Vitamin B6 | 0.115mg | 0.028mg |
| Potassium | 446mg | 220mg |
| Selenium | 5.7μg | 2.1μg |
As the data shows, shiitake mushroom caps are higher in protein, fat, vitamins, and minerals than the stems. The stems do contain a slightly higher amount of fiber, but overall are not as nutrient dense as the caps.
Health Benefits of Shiitake Mushroom Caps
Consuming shiitake mushroom caps offers many excellent health benefits, while the stems provide negligible health value:
- Contain antioxidants – The caps are a great source of selenium, vitamin C, and antioxidative phenolic compounds.
- Support immune function – Compounds in the caps boost immunity by protecting cells from damage and inhibiting viral growth.
- Promote heart health – The caps contain compounds that help lower cholesterol, blood pressure and risk of cardiovascular disease.
- May have anti-cancer effects – Extracts from the caps exhibit antitumor, anti-proliferative properties against certain cancer cells.
- Provide anti-inflammatory benefits – The caps are rich in anti-inflammatory polysaccharides that help reduce inflammation.
Research overwhelmingly shows that the caps, rather than the stems, are responsible for shiitake mushrooms’ health-promoting effects.
Possible Concerns with Eating the Stems
While not necessarily harmful in small amounts, there are some potential concerns with over-consuming shiitake mushroom stems:
- May cause digestive issues due to high fiber content, particularly the fiber chitin which humans cannot digest.
- Contains a higher concentration of the amino acid eritadenine than the caps. In large amounts, eritadenine can interfere with vitamin B6 metabolism.
- Lower in key micronutrients than the caps, providing less nutritional benefit.
- Can have a tough, fibrous texture that is unpleasant to eat in abundance.
For these reasons, it is recommended to remove and discard the stems during preparation and focus consumption on the nutritious caps.
Shiitake Mushroom Stem Tea
While not suitable for eating whole, shiitake mushroom stems can be used to make a beneficial medicinal tea. Here is a simple stovetop recipe:
Ingredients:
- 5-10 shiitake mushroom stems
- 4 cups water
- 1 teaspoon fresh grated ginger
- 1 cinnamon stick
- 1 teaspoon honey or lemon (optional)
Instructions:
- Clean mushrooms stems by wiping with a damp cloth or quickly rinsing.
- Chop the stems into 1-2 inch pieces.
- In a small pot, combine water, ginger, cinnamon stick and chopped mushroom stems.
- Bring the liquid to a gentle simmer over medium-high heat. Then reduce heat and let simmer for 15-20 minutes.
- Strain out and discard the mushroom stems pieces through a fine mesh strainer or cheesecloth.
- Stir in honey or lemon to taste. Drink tea warm.
Sipping this simple shiitake stem tea is an easy way to gain nutritional and anti-inflammatory benefits from the stems rather than eating them directly.
Conclusion
In conclusion, shiitake mushroom stems are not eaten and are generally removed before cooking the mushroom caps because:
- The stems have an undesirable tough, woody, fibrous texture.
- The stems lack flavor and taste mildly bitter.
- The stems contain higher amounts of difficult to digest fiber and eritadenine.
- The caps are more nutrient dense, containing higher amounts of beneficial vitamins, minerals and compounds.
- Research shows the caps provide health benefits, while the stems have negligible benefits.
- Consuming high quantities of the stems may cause digestive issues.
Shiitake mushroom stems can be used to add flavor to broths or make tea. But the caps should be the part of the mushroom consumed for optimal nutrition, enjoyment and health effects.
