The natural and high-quality black fungus slices are thin and dark in color. There are light white hairs on the back of the ear, and there are vein-like lines on the ear surface, called "ear tendons". The pieces of dried goods are complete, dry and loose, with few impurities, light to the touch, and no salty, sweet or astringent taste. Real fungus has strong water absorption (5 grams of dry fungus can absorb 50 ml of water). After absorbing water, the flesh is tough and elastic, and the volume can increase more than 10 times.

Some black workshops generally produce "artificial fungus" through the following two methods.

1. Soak the white-backed fungus, yellow-backed fungus or ground fungus in brine, brown sugar, magnesium sulfate, ink and other solutions, and then dry it in the sun until it becomes black, shiny and shiny. Big and thick "black fungus". After eating this "fungus", poisoning phenomena such as vomiting and diarrhea are likely to occur.

2. Use brown sugar, water, refined powder, and seaweed gum to make a clay-like black porridge, then use a small spoon to scoop a little black porridge and pour it on the glass slice soaked in calcium chloride water, and then Another piece of glass and the extruded ear-shaped slice are soaked in calcium chloride water and finally dried in the sun. There is no harm in eating this "artificial fungus", but it is obviously not comparable to the nutritional value of natural fungus.

The fungus processed by the first method has a dull color on the surface of the ear, with "fine white frost" hanging on the back of the ear. The pieces are stuck and curled into clumps, and they feel heavy and hard to the touch. Put it in your mouth and taste it carefully. The taste is unusual: the salty one is salt, the sweet one is brown sugar or honey, the astringent one is magnesium sulfate or copper sulfate, and the bitter one is probably salt brine. In addition, its water absorption is relatively poor, and its volume can only increase 3 to 5 times after absorbing water.

The fully artificial fungus made by the second method is colored with brown sugar, so it tastes sweet, while natural fungus has no sweetness. The seaweed glue used in the fully artificial fungus is a natural food additive and has very little water absorption, so its volume growth after soaking in water is also very limited. In addition, soak the fungus in a small amount of water, and then add soda water to the water. The water soaked in the "artificial fungus" will become turbid.