Risk warning about ginkgo nut

Ginkgo trees have beautiful shapes, with leaves that are green in spring and summer and golden in autumn. They are widely planted as garden trees and roadside trees. Every October, ginkgo fruits are ripe. Some consumers buy them, and some pick up the fallen fruits to eat. However, improper consumption can easily lead to risks. How should consumers eat them safely? Here are the risk warnings.

What are Ginkgo Nuts?

Ginkgo nuts, commonly referred to as gingko nuts, refer to the seeds of the fruit of the ginkgo tree, also known as ginkgo nuts, which are both food and Chinese medicinal materials. Ginkgo nuts are oval or spherical, with a yellow outer skin when mature. They fall off the tree naturally as the autumn wind blows. Ginkgo fruit consists of a fleshy exocarp, a hard mesoprena (shell), a thin endocarp (coating), endosperm (kernel flakes) and embryo (as shown below). Peeling off the exocarp will give you the hard ginkgo seeds, commonly known as ginkgo nuts. The dried ginkgo shell is silvery white. After removing this hard shell, you will get the ginkgo kernel wrapped in a silver or light brown coating. The ginkgo kernel is cut open from the middle, and the core inside is the embryo of the ginkgo nut. The remaining part is called the endosperm, which is the main edible part of the ginkgo nut. The fresh ginkgo kernel is green like jade, and is light yellow or light green when cooked. It has a slightly bitter taste and is soft and delicious when eaten hot.

Dried ginkgo kernels contain about 60%-70% starch, 13% protein and 3% fat, as well as trace nutrients such as sterols, vitamins, riboflavin, trace elements and inorganic salts. In addition, ginkgo contains ginkgolide and ginkgo flavonoids, the unique active ingredients of ginkgo, and proper consumption is beneficial to improving cardiovascular and cerebrovascular functions.

(Photo source: Chinese Society of Food Science and Technology)

Improper consumption poses risks

Ginkgo nuts have edible value. In addition to the above ingredients, they also contain toxic ingredients such as ginkgolic acid, ginkgolactone, hydrocyanic acid and allergenic proteins. Improper or excessive consumption may cause toxic side effects. The embryo of ginkgo nuts contains most of the hydrocyanic acid, ginkgolactone and a small amount of ginkgolactone in the ginkgo kernel, and is the part with the highest content of toxic ingredients in the ginkgo kernel. Ginkgo toxins and allergenic proteins are mainly found in the edible endosperm. Ginkgo toxins are the main toxic substances that cause acute ginkgo poisoning. Ginkgo poisoning often occurs within 3-4 hours after consumption. Symptoms include fever, vomiting, abdominal pain, diarrhea, convulsions, and difficulty breathing. In severe cases, death may occur due to respiratory failure. A few people show sensory disorders and lower limb paralysis. After eating ginkgo nuts, if poisoning symptoms appear, induce vomiting immediately and seek medical attention in time.

How to eat ginkgo nuts scientifically?

First, remove the toxic parts. For shelled ginkgo nuts purchased from the market, peel off the hard shell first, boil them in water for 10 minutes to remove the membrane, and remove the embryo before cooking. If you pick up ginkgo nuts, wear gloves when peeling off the outer skin because the fleshy outer skin of the ginkgo nut contains a high content of ginkgolic acid, which will corrode the skin. You can also put the ginkgo nut in water to rot the outer skin to make it easier to remove the ginkgo nut.

Secondly, remember that ginkgo nuts cannot be eaten raw. However, high-temperature cooking methods can remove most of the toxic components in ginkgo nuts, reduce allergenicity, and ensure food safety. Different cooking methods require full preparation and heating to eliminate or reduce the toxicity of ginkgo nuts.

1. Steaming

Put the pot in boiling water and steam over high heat for more than ten minutes.

2. Boil/stew

Put the ginkgo nuts in a pot after the water boils and boil for 10 minutes. Stew them with meat for a long time (such as 1 or 2 hours) without affecting the taste of the ginkgo nuts.

3. Stir-fry

Before cooking, you need to boil the water first, and then stir-fry it with other side dishes.

4. Microwave

Put a small amount of ginkgo nuts into an envelope (preferably a kraft paper bag) and put it in the microwave. Generally, heat it until the shell breaks and then eat it. However, it is not recommended to use microwaves to heat and cook ginkgo nuts in shells to avoid danger due to improper operation.

Furthermore, the amount of consumption should be controlled. Do not consume too much cooked ginkgo nuts. It is recommended that adults take 10-20 pieces, children should not take more than 5 pieces, and infants and young children should not eat them.

Ginkgo can be cooked in a variety of ways, such as braised pork with ginkgo, chicken stewed with ginkgo, sweet soup with white fungus and ginkgo, etc. It can also be made into porridge, or fried directly as a snack. Ginkgo nuts are rich in amylopectin, so they should be eaten hot after frying. They have a soft and glutinous taste, and become hard after cooling.

Expert Writer

Zhang Lei, researcher at the National Food Safety Risk Assessment Center

Yang Xiaoming Professor of College of Food and Bioengineering, Jiangsu University

Huang Jian, Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention