The nutritional characteristics and health effects of fruits are similar to vegetables, mainly providing vitamin C, beta carotene, B vitamins, potassium, calcium, magnesium, dietary fiber and phytochemical components (such as flavonoids, anthocyanins, organic acids Wait). The main nutrient content of common fruits is shown in Table 4-1. Slightly different from vegetables, fruits usually contain more sugar and organic acids, so the taste is sweet or sour or both. The sweet and sour taste of fruit depends mainly on the ratio of sugar and organic acids.

The sugars in 　　 fruit are mainly sucrose, glucose and fructose, which are converted from starch after the fruit begins to ripen. Many fruits, such as apples, pears, peaches, bananas, etc., are still undergoing conversion from starch to sugar after picking, so they will be sweeter and sweeter. The sugar content of different fruits varies greatly, such as peaches, plums, apricots, cherries, grapes, bananas, lychees, longan, kiwi, etc., mainly glucose, followed by fructose, sucrose, sorbitol; figs, apples, pears , Loquat is mainly fructose, followed by glucose, sorbitol and sucrose; pineapple and mango are mainly sucrose.

　　The sour taste of fruits comes from organic acids, such as citric acid, malic acid and tartaric acid. Citric acid is abundant in fruits such as citrus, pineapple, and pear; malic acid is mainly found in fruits such as apples, bananas, cherries, and plums; tartaric acid is mainly found in grapes. Generally, the organic acid content gradually decreases during fruit ripening, and the acidity will also decrease. Organic acids can stimulate the secretion of human digestive glands, increase appetite, help food digestion, protect and promote the absorption of vitamin C, iron and other nutrients.

　　Fruit is also rich in dietary fiber (especially pectin), which can promote bowel movements and relieve constipation; it can lower blood cholesterol and prevent arteriosclerosis. Various phytochemicals in fruits, such as carotenoids, flavonoids, anthocyanins, etc., have antioxidant, anti-cancer, immune-modulating, hypolipidemic and other physiological activities. In addition to nutritional and health effects, eating fruit is still a wonderful taste enjoyment, which is one of the signs of a higher standard of living. The "Dietary Guidelines for Chinese Residents 2007" recommends that adults eat 200 to 400 grams (4 to 8 taels) of fruit per day.

　　Although fruits and vegetables have many similarities in terms of nutrients and health effects, they are two different foods with different nutritional values, as pointed out in the "Dietary Guidelines for Chinese Residents 2007", Fruits and vegetables cannot be replaced with each other.

　　Many people think that fruits are better than vegetables, so they only pay attention to fruits instead of vegetables every day. In fact, the nutritional value of most daily fruits is not as good as vegetables, especially green leafy vegetables. Apples, pears, peaches, apricots, grapes, bananas and other fruits have low vitamin C and beta-carotene content and low mineral content. Generally speaking, most vegetables (especially dark vegetables) have higher content of vitamins, minerals, dietary fiber and phytochemicals than fruits, so fruits cannot replace vegetables. On the other hand, fruits are rich in sugar, pectin, organic acids and aromatic substances. Eating fruits has a stronger sense of enjoyment, and they are often eaten raw without heating, and the nutrients are almost not destroyed, so vegetables cannot completely replace fruits.

　　Fruit color mainly comes from chlorophyll, carotenoids, anthocyanins, etc. Chlorophyll can dye plants green, carotenoids can make plants appear orange, anthocyanins are water-soluble pigments, showing purple. Anthocyanins interact with metal ions such as potassium, sodium, and iron to produce blue, and interact with acidic substances to produce red. These pigments are all phytochemicals and are good for health, and the darker the color of the fruit pulp, the greater the health value. Under the premise of diversification, it is recommended to prefer dark-colored fruits.