The fifth grade explanatory text is 200 words

Apple, also known as Taopo, is a kind of drupe, which consists of several seeds wrapped in juicy pulp and belongs to pear. Commercial apples are native to West Asia or Eastern Europe, and there are about 7,500 varieties in the world. They are sweet, sour and nutritious, and are one of the fruits suitable for all ages.

nutritive value

The water content of fresh apples is 85%.

Apples are rich in carbohydrates, vitamins and trace elements. Especially the content of vitamin A and carotene is higher.

Effects on disease and health

It is rich in water-soluble dietary fiber-pectin. Pectin has the functions of protecting intestinal wall, activating beneficial bacteria in intestinal tract, regulating gastrointestinal function, absorbing water, eliminating constipation, stabilizing blood sugar, beautifying skin, adsorbing bile and cholesterol, and can effectively prevent hyperlipidemia, hypertension and hyperglycemia, clean intestinal tract and prevent colorectal cancer.

Malic acid and citric acid in apple sour taste can improve gastric juice secretion and promote digestion.

Malic acid can also stabilize blood sugar and prevent diabetes, so diabetics should eat sour apples.

Apples are rich in potassium, which can prevent and treat hypertension. China people's salt intake is seriously excessive, which leads to the retention of sodium and water in the body and promotes hypertension. Potassium can increase the excretion of sodium from the kidney and reduce the content of sodium in cells, thus lowering blood pressure. Potassium can also dilate blood vessels, and together with pectin can prevent metabolic syndrome.

Apples can also prevent cancer and lead poisoning.

Apple juice has a strong effect on killing infectious viruses. People who eat more apples are much less likely to catch a cold than those who don't eat or eat less apples. Therefore, some scientists and doctors call apples "all-round healthy fruits" or "general practitioners". Now the air pollution is more serious. Eating more apples can improve the respiratory system and lung function, and protect the lungs from pollution and smoke.

Apple has a natural and pleasant aroma, which has obvious effect of eliminating depression.

Traditional Chinese medicine believes that apples are flat in nature and have the effects of nourishing the heart and moistening the lungs, promoting fluid production and detoxifying, benefiting qi and regulating the stomach, sobering up and calming the liver.

Diet should be avoided.

Apples should not be eaten with seafood. Apples contain tannic acid. Eating with seafood not only reduces the nutritional value of seafood protein, but also tends to have symptoms such as abdominal pain, nausea and vomiting. Similarly, other fruits with more tannins, such as strawberries, bayberries, persimmons, pomegranates, lemons, grapes and sour pomelo, should not be eaten with seafood.

Apples are rich in nutrition. Chewing slowly when eating apples is not only conducive to digestion, but also conducive to reducing human diseases.

Expectant mothers eat an apple every day, which can reduce the reaction during pregnancy.

Purchase, preservation and eating methods

There are many kinds of apples, with different appearance and pulp characteristics, and their applicability in seasons and various uses is also very different.

Fresh apples should be solid, crisp and beautiful in color; Mature apples have certain fragrance, compact texture and easy storage; Immature apples have bad color and no fragrance, and may shrink after storage; Overripe apples droop easily when pressed lightly on the surface. Apple will have internal damage and collision scars after being frozen for a period of time. Irregular brown or brown spots will not seriously affect the eating quality of apples.

Apples that grow without bagging are unsightly in appearance, but have high sugar content. From early spring to summer, apples in this period are all stored apples, so the taste is not very fresh.

The skin of fresh apples is sticky, and you can see a layer of frost. This is not because of waxing, but a layer of natural waxy substance, which can protect apples. Besides, some apples taste as sweet as honey. This is because a special kind of sugar will be formed in fruit after being fully irradiated by sunlight. This kind of sugar has high osmotic pressure and can absorb water from surrounding tissues, so it tastes like honey.

Apples can be kept fresh for 7 ~ 10 days in the shade, and can be kept fresh for longer if they are put into plastic bags and put in the refrigerator. If you have extra apples, you can make them into candied fruit or jam and keep them in the refrigerator.

If immature kiwifruit or pear is put into a plastic bag with apples, the ethylene released by apples can make other fruits mature and make kiwifruit and pear soft. But if apples are put together with other mature fruits and vegetables, they will accelerate the decay, so they should be avoided.

Precautions for eating

After apple is cut or peeled, it can be soaked in light salt water or sprinkled with lemon juice to prevent discoloration.

Vitamins, pectin and other effective ingredients in apples are mostly contained in and near the peel, so apples should be washed and eaten, and try not to peel them. Apple with no pesticide and low pesticide is preferred.

Related recipes and food collocation

Hot toffee apple

Peel the apple and cut it into pieces; Heat a proper amount of oil in a wok, pour in white sugar, simmer until the sugar is thin, then add diced apples, turn them repeatedly until the sugar is hanging, and then take them out of the wok and serve.

The dish has the effects of appetizing, harmonizing stomach and prolonging life, and is suitable for people with poor appetite.

For the public.

Most people can eat it.

Apples, apples, temperate fruit trees. Cross-pollination environment requires ① temperature: the annual average temperature is 8 ~ 14℃. The ten-day average temperature in Leng Yue is not lower than-14℃; There is a defoliation dormancy period of more than 50 days, and the daily average temperature around 7℃ is greater than 10 days; The average monthly temperature in summer is lower than 27 ~ 28℃. ② Rainfall: When the growing season is dry and hot, the water demand is large. The annual rainfall of 500 ~ 800 mm basically meets the needs. Rainy flowering will affect pollination and fruit setting. ③ Illumination: the annual sunshine is less than 1500 hours, which is not conducive to the coloring of red varieties. In areas with high altitude and low accumulated temperature, strong sunshine can supplement part of the heat and contribute to the fruit development of mid-late maturity varieties. ④ Soil: When the pH value is lower than 4 ~ 4.5 or higher than 7.5 ~ 8, it is easy to cause physiological diseases of apples. When the total salt content is below 0. 13%, it can grow normally. Sandy loam is the most suitable soil.

Description of nutritional imbalance symptoms in apples

Apple leaves are yellow and red in spring when nitrogen is scarce, and thin and yellow in summer. In severe cases, the leaves are early and the leaves are small. Excessive nitrogen will cause the dark green leaves of apple leaves to become bigger and wrinkled.

The young leaves of phosphorus-deficient apples are small dark green, the adult leaves are dark purple and the bronze color is dim. The petiole and new shoots on the back of the leaves are purple with brown spots, and the leaves are at an acute angle with the new shoots.

The tips of the leaves in the middle and lower parts of the new shoots of potassium-deficient apples turn green, the leaf edges are yellow or dark purple, they shrink and curl, then they are necrotic and scorched, and expand to the top. Seriously, the whole leaves are reddish brown and brown, and the dead leaves have not fallen for a long time. Potassium-deficient fruits are poor in color and taste when they are young and ripe, so they are not resistant to storage.

Apple fruit is also bitter pox because of calcium deficiency. Before harvesting, the surface of diseased fruit sinks before the top of fruit, and the pulp becomes soft, dry and bitter, which leads to the increase of diseases during storage. Calcium deficiency can also cause water heart disease, the translucent waterlogging of pulp expands radially, and the diseased tissue is soft and smelly; During storage, the diseased spots developed continuously, and finally the intercellular space of pulp was filled with juice until it rotted.

Light green spots or grayish green spots appear between veins of magnesium-deficient leaves of apples, which spread to the leaf margin and quickly turn yellow-brown to dark brown, and then the necrotic leaves between veins and leaf margins fall off. The top is a rosette with thin and pale leaves; In severe cases, the fruit can not mature normally, and the fruit is small, with poor color and flavor.

Apple leaves turn green and yellow due to sulfur deficiency. In severe cases, the shoots wither, and the fruit is small and deformed, with light color, thick skin and little juice.

Apples are prone to iron deficiency. The chlorosis and yellowing of new shoot leaves is called yellow mosaic disease, and the degree of chlorosis is aggravated in turn. Summer and autumn shoots are more common than spring shoots, and the diseased leaves are mostly in clear reticular mosaic, which is called yellow mosaic. If it is severely yellow and white, the leaf edge can also be burned, dried up and fall off early, forming dead branches or bald branches. It has repeatedly led to the decline of the whole factory.

Apple suffers from lobular disease peculiar to zinc deficiency. The new shoots are abnormal and extremely short, and a large number of twigs sprout from axillary buds, and the mottled leaves at the tip are small and hard. In the late stage of severe zinc deficiency, leaves fell off and new shoots died.

The new shoots of boron-deficient apples are damaged or even withered, with thin and weak lateral branches, thick leaves and many fallen leaves, short and brittle petioles, and twisted veins like lobular disease. The symptom of boron deficiency in apple fruit is that there are brown spots on the surface of young fruit, which dries up after cork, and the skin is uneven and cracked, which is called fruit shrinkage disease. The diseased fruit falls off or dries up before maturity and hangs on the tree. The fruit with mild symptoms is brown cork or sponge cavity, and the pulp of the affected part is bitter.

Apple's lack of copper leads to branch blight or summer shoot blight. The tender leaves turn green to white and brown, and the tender branches bend. In severe cases, leaves fall off and branches die. Bark is a colloidal blister-like brown or reddish-brown rash, which gradually spreads to form a series of overlapping longitudinal grooves, and yellow or red gum flows out in rainy season; Some peels also shed jelly to form irregular brown spots; Small fruits crack and fall off easily.

The leaves of manganese-deficient apples are light green and mottled, developing from the leaf margin to the midvein. In severe cases, the pulse turns brown and necrotic, and the leaves are all yellow. The symptoms of some fruit trees are not limited to the new shoots and young leaves, but also can appear on the middle and upper old leaves. Apple has excessive manganese, green leaves, necrotic trunk endothelium and rough epidermis.

Brief introduction of apple computer

Apple Computer Company was founded by Steve Jobs? Wozniak and Ron Wayne were founded in April 1976. 1In the spring of 975, Apple I was designed by Wozon. At that time, Byte's computer store bought 50 Apple I's, and the price was 666.66 dollars. 1976, Woz completed the design of Apple.

1977 Apple was officially registered as a company and launched a new Apple logo that is still in use today. At the same time, Apple also got its first investment-92,000 dollars from Mike Markkula.

1978, when Apple was preparing to go public, Xerox pre-purchased1000000 dollars of Apple stock, and allowed Apple engineers to study the graphical interface of PARC operating system, which had long been regarded as garbage by Xerox. But Apple's engineers turned decay into magic and brought the graphical interface into a brand-new time and space.

Apple ⅱ has many firsts in the history of microcomputer: it has a plastic shell for the first time; Bring your own power supply equipment for the first time without a fan; Intel Dynamic Memory; This is the first installation; For the first time, the motherboard is equipped with 48K capacity; Playing color games for the first time; Set the built-in speaker interface for the first time; Install the game control key for the first time; For the first time, it has high-resolution graphics function; CPU and motherboard * * * enjoy RAM for the first time ................................................................................................................................................................. 1979, Woz won the Hope Award. This award is specially set up for young computer scientists who have made outstanding contributions. Her name is Grace, a famous female computer scientist and one of the earliest programmers in the world. m？ I hope (1906- 1992) will be named after him. Generally, only one person will be awarded every year from 197 1.

Apple Computer Company described the company's performance as follows: Apple Computer Company launched the personal computer revolution in the 1970s through Apple II, and the introduction of Macintosh completely transformed personal computers in the 1980s. Through its creative hardware, software and Internet technologies and equipment, Apple is committed to bringing the best computer experience to students, educators, creative experts and ordinary consumers all over the world.