Grifola frondosa, whether dried or fresh, is loved by people. Its taste is fragrant, the meat is crisp and tender, it is as delicious as shredded chicken and as crisp as magnolia. There are many ways to eat, such as frying, burning, rinsing and stewing. Can make soup, stuffing and cold current; Cold dishes are crisp and tender, fried and delicious; Roast stew has the characteristics of "instant use, crisp after long cooking", and the soup has a particularly good flavor, which is a rare delicacy at the banquet. Fresh Grifola frondosa is tender, crisp, smooth and refreshing, suitable for cooking and soup making. Dried Grifola frondosa has a strong fragrance and is regarded as a delicacy and feast treasure; The canned Grifola frondosa is delicious. Grifola frondosa is characterized by high protein, low fat, complete essential amino acids (cereals generally lack 1 ~ 2 kinds of essential amino acids) and rich in various vitamins. Japanese people like to rinse hot pot with fresh Grifola frondosa. Dried products still have a unique flavor after soaking, so Grifola frondosa is a good gift in Japan, ranking third after mushrooms and Flammulina velutipes in sales.
Grifola frondosa, like other edible fungi, not only tastes delicious, but also has certain health care functions. Chinese medicine believes that Grifola frondosa is sweet and cool, non-toxic, and has the effects of invigorating spleen and qi, clearing away heat and relieving summer heat. In addition, it can lower blood pressure, enhance the body's disease resistance and accelerate wound healing. Grifola frondosa is rich in lysine and arginine, which can promote children's intellectual development, especially suitable for pregnant women and lactating women. It can promote the intellectual development of the fetus and make the baby smart and strong. Therefore, it is called "Lizi Mushroom". Grifola frondosa contains a high proportion of polysaccharides, which can improve human immunity. Therefore, Grifola frondosa is a kind of "green" health food with the same origin of medicine and food, which can enhance people's physique if eaten regularly.
Protein and amino acids
1. protein. To evaluate the nutritional value of food, generally we mainly evaluate its protein, that is, the nutritional value depends on the protein content and quality of food.
Protein content is usually determined by micro kjeldahl method, and then the protein content of the sample is obtained by multiplying the nitrogen content by the protein conversion coefficient of 6.25. The cells of mushroom fungi also contain non-protein nitrogen-containing substances such as chitin, so the measured value is higher than the real protein content, or the data recorded in various literatures are different. In order to solve this problem, Fitzpatrick suggested using N×4.38 as the conversion formula, which can accurately express the actual content of fungal protein.
Among the 10 rare edible fungi listed in the table 1- 1, the protein content of Grifola frondosa is 3 1.5%, second only to the most famous rare species in China (39.3%), and higher than that of Morchella (31.4). This shows that Grifola frondosa is a veritable high-protein mushroom variety.
Table 1- 1 Nutritional components of Grifola frondosa and other edible fungi (dry weight,%)
Comparatively speaking, the protein content of dried Grifola frondosa is 2-4 times higher than that of cereals, such as rice is 7.3%, wheat is 12.7%, and the protein content of dried Grifola frondosa is as high as 3 1.5%. Although the protein content of soybean is as high as 39. 1%, its protein utilization rate is only 43%, while the protein utilization rate of Grifola frondosa is as high as 80%, mainly because the essential amino acid content in soybean is only 0.46%. If soybean and Grifola frondosa are eaten together, the protein utilization rate of soybean can be increased to 79% ~ 80%.
The protein content of fresh Grifola frondosa is much higher than that of spinach, potatoes and tomatoes, even higher than that of milk, compared with vegetables, meat, eggs and milk (Table 1-2). Although not as good as meat and eggs, the fat content and calories of Grifola frondosa are much lower. Therefore, nutritionists have a high evaluation of the nutritional value of Grifola frondosa, calling it "plant meat" with high protein, low fat and low calorie.
Table 1-2 Comparison of nutritional components between fresh Grifola frondosa and other foods (%)
Note: ① Heat is fresh product 100g.
② A person weighing 65kg needs 6552 kj/ day for basal metabolism.
2. Amino acids. Amino acid is the basic unit of protein, which has two configurations: L-type and D-type. The amino acids in natural protein are all L-shaped. Of the total amino acids, 1/3 is a free amino acid, and the remaining 2/3 is bound in protein.
There are more than 20 kinds of amino acids in natural protein. Amino acids can be divided into essential amino acids and non-essential amino acids according to whether the human body can synthesize them. Essential amino acids are essential for human growth and development, but they cannot be synthesized or transformed by themselves and must be supplied through food. There are 8 kinds of essential amino acids, including lysine, leucine, isoleucine, valine, threonine, phenylalanine, methionine and tryptophan. On the contrary, nonessential amino acids refer to those that can be synthesized or transformed by the human body itself.
Grifola frondosa contains 18 amino acids, including 8 essential amino acids (table 1-4). The amino acid content of Grifola frondosa is also higher than other foods, especially the tryptophan content of essential amino acid is higher than that of lean pork and eggs. It can be seen that Grifola frondosa contains comprehensive and balanced nutrition and belongs to the top grade of edible fungi. It is particularly worth mentioning that lysine and leucine, which are rarely contained in cereals, and tryptophan, which is rarely contained in beans, are also relatively high in Grifola frondosa. Therefore, Grifola frondosa and other foods can complement each other in nutrition, so that the intake ratio of amino acids is closer to the pattern needed by the human body, thus improving the nutritional potency of food. It should be pointed out that the amino acid content of artificially cultivated Grifola frondosa is higher than that of wild Grifola frondosa, which may be due to the fact that the nutrition of artificially cultivated materials is higher than that of natural substrates.
Table 1-4 Comparison of amino acid content of Grifola frondosa and other foods per 100g (g)
Table 1-4 Comparison of amino acid content of Grifola frondosa and other foods per 100g (g) (continued)-1
Note: ① Those marked with * in the table are essential amino acids, accounting for about 40% of the total.
② Grifola frondosa is recognized by the Quality Inspection Center of the Ministry of Agriculture; Others are quoted from the food ingredient list.
Vitamins and minerals
1. vitamins. Vitamins do not provide heat energy for the body and do not participate in the composition of tissues, so the demand for vitamins is very small, but vitamins are important substances necessary to maintain the normal life activities of organisms, and their main function is to participate in the metabolism of organisms as coenzymes. The human body can only synthesize a few vitamins, and most vitamins need to be supplied through food. Grifola frondosa is rich in vitamins, such as vitamin B 1 (thiamine), vitamin B2 (riboflavin), vitamin C (ascorbic acid) and vitamin VE (table 1-5).
Table 1-5 Vitamin content per100g of dried Grifola frondosa and other edible fungi (mg)
(1) Vitamin E. The proportion of vitamin E in Grifola frondosa fruiting body is very high, ranking second among 1 358 foods listed in the food composition table, second only to linseed oil (389.9 mg/ 100 g). Vitamin E can eliminate toxic peroxides in human body, prevent lipid peroxidation of cell membrane, inhibit the formation of chloasma and liver cell aging in middle-aged and elderly people, and has the function of delaying the aging of the body. Middle-aged and elderly people, especially menopausal women, have good anti-aging and beauty effects. In particular, vitamin E is beneficial to human germ cells. When vitamin E is deficient, human reproductive function will decline.
(2) Vitamin B 1 is also called thiamine. Its main function is to protect the nervous system, promote individual development and participate in the catabolism of sugar in the form of coenzyme. Mild deficiency of vitamin B 1 can cause fatigue, depression, impatience, loss of appetite, growth retardation and so on. If vitamin B 1 is deficient for a long time, it may lead to emaciation, edema, decreased heart function and beriberi. A recent new study shows that eating foods rich in vitamin B 1 or taking vitamin B 1 tablets can reduce the risk of heart disease. The content of vitamin B 1 in Grifola frondosa is relatively high, reaching 1.47 mg/g dry weight. An adult eating 50 grams of fresh Grifola frondosa is enough to supply vitamins for one day and prevent beriberi.
(3) Vitamin C, also known as ascorbic acid, is the first vitamin found in citrus. Vitamin c is of great significance to human health. Can prevent scurvy. Promote human metabolism and wound healing; Improve the immunity of the body; Regulate the metabolism of fat, lipid and cholesterol; Improve teeth and bones; Strengthen the capillary wall and improve blood vessels; At the same time, vitamin C also has the function of detoxification. When toxic substances, such as lead, arsenic and benzene, enter the body, vitamin C will combine with them to form anti-bad blood cells, which will be excreted with urine. In addition, vitamin C can prevent the formation of nitrite in the body. The carcinogen ammonium nitrite is produced by the combination of nitrite and amine. Without nitrite, ammonium nitrite cannot be formed, which has a good effect on cancer prevention. Lack of vitamin C can lead to scurvy, mainly manifested as swelling and loosening of teeth, capillary bleeding and other symptoms. American nutritionists Barra and Katz also found that people's IQ is indirectly related to the content of vitamin C in blood. The blood vessels that transport nutrients in human brain cells will be blocked and thinned due to the lack of vitamin C, which will lead to the decline of brain function. Grifola frondosa is rich in vitamin C. Every gram of dried Grifola frondosa contains vitamin C 100 mg.
2. minerals. The chemical substances remaining in the ash after the burning of Grifola frondosa fruiting body tissue include potassium, phosphorus, sulfur, sodium, calcium, magnesium and trace elements such as copper, iron, manganese, molybdenum and cadmium. Minerals can make bone structure have certain strength and hardness, activate enzyme system, control body fluid balance and adjust acid-base balance, and also have special effects on muscle and nerve stress. Mineral deficiency can cause a series of diseases of human body, such as potassium deficiency can cause rapid heartbeat, arrhythmia, muscle weakness, diarrhea, abdominal distension, etc. Calcium deficiency can cause osteomalacia and osteoporosis, and the elderly are prone to dementia, while calcium deficiency in children will seriously affect growth and development. Phosphorus deficiency can lead to weakness, loss of appetite, muscle weakness, bone pain and so on. Iron deficiency can cause iron deficiency anemia and so on.
Both wild Grifola frondosa and cultivated Grifola frondosa contain many minerals beneficial to human body, such as potassium, phosphorus, sulfur, magnesium, calcium, iron, sodium, zinc, copper, manganese, boron, chromium and selenium (table 1-6).
Table 1-6 Mineral content in dry wild Grifola frondosa and cultivated Grifola frondosa per100g (mg)
Organic chromium in Grifola frondosa can cooperate with insulin to maintain normal glucose tolerance, which has effects on liver cirrhosis and diabetes.
Trace element selenium (Se) is a chemical element between metal and nonmetal, and its content in some sulfide minerals in nature is only 1%, so it is a rare element.
In 18 17, Swedish chemist Breezing discovered selenium in the residue of sulfuric acid production, and it was not until 1957 that selenium was found to be a protective factor against nutritional liver necrosis. 1973 The United Nations Health Organization declared that "selenium is an essential trace element in animal life". Then, China medical household selenium has made remarkable achievements in the prevention and treatment of endemic diseases such as Keshan disease and Kaschin-Beck disease, and won the highest honor award of the World Trace Element Research Center-Schwartz Award with 1984. Later, after a lot of research, scientists in China proved that selenium has preventive and therapeutic effects on cancer, cardiovascular and cerebrovascular diseases, liver and kidney diseases, diabetes, hemolytic anemia, asthma, arthritis, cataracts and children's developmental retardation. Selenium can antagonize, detoxify and excrete toxic substances such as cadmium, mercury, arsenic and lead in human body. In the international research on the relationship between selenium and human health, China has always been in a leading position. In June of 1988+00, the Nutrition Society of China listed selenium as one of the 15 nutrients necessary for human life, and stipulated that the daily intake of selenium per person was 12-month-old baby 15 microgram,13-year-old and 4-6-year-old children 20 microgram.
There are more than 40 countries and regions in the world lacking selenium, and the situation of selenium deficiency in China is serious. 1980 312,278 forage and soil samples were collected and measured in 1094 counties (about half of the country) in 30 provinces, municipalities and autonomous regions (excluding Taiwan Province Province), and a serious shortage was found. There are 474 counties in selenium-deficient areas with selenium content of 0.03 ~ 0.05 mg/kg, accounting for 43% of the total; There are 207 counties with selenium content of 0.06 ~ 0.09 mg/kg, accounting for19% of the total; Only 102 counties are normal (≥0. 10 mg/kg), accounting for 9% of the total. It can be seen that 72% of counties in China are deficient in selenium (of which13 counties are seriously deficient in selenium), which will inevitably lead to the production of a large number of low-selenium grains and vegetables, forming a low-selenium food chain, resulting in a low proportion of selenium in food sources for people and livestock, which will affect people's and livestock's health. Selenium must be supplemented in these areas, otherwise local people are prone to selenium deficiency diseases, such as hair loss and hemolytic anemia. Therefore, it is necessary to study and develop the social significance of selenium-enriched food.
In recent years, studies at home and abroad have found that many edible fungi, such as Grifola frondosa, Lentinus edodes, Pleurotus ostreatus and Grifola frondosa, have selenium-enriched ability. The selenium content of naturally cultured Grifola frondosa is only 0.0 1 mg/kg dry product, but it can be artificially increased by using the selenium-enriched ability of Grifola frondosa mycelium. The experiment of Liang Ying et al. (2000) showed that selenium application in the culture medium could increase the selenium content of Lentinus edodes by 129.8 1 mg/kg dry product, which was more than 300 times higher than that of the control (0.42 mg). The absorption rate of organic selenium contained in edible fungi is as high as 97.5%, which is an excellent selenium supplement food. For example, the selenium content of Grifola frondosa cultivated with selenium can reach 1mg per kilogram of dried product. According to the minimum requirement standard of selenium for people over 7 years old in China 1 998, the selenium content of 1 kg dry product (1 1,000 micrograms) can be consumed by 1 person for 20 days, and 50 grams per day can meet the national regulations.