1. Cereals: seeds of Gramineae plants, mainly including wheat, rice, corn, sorghum and millet. Cereals play an important role in the diet of China people. It provides 73% energy and 65% protein in daily diet, and is also the main source of inorganic salts and B vitamins. The protein content of cereals generally varies between 7- 16%, and lysine is the most lacking amino acid composition. The main form of cereal carbohydrate is starch, and its content can reach more than 70%. B vitamins contained in cereals are the main sources of vitamin B 1 and nicotinic acid in diet.
2. Beans
Include soybeans and other miscellaneous beans. Soybean contains 36-40% protein and 15-30% fat. Soybean protein is the best source of plant protein and contains more lysine, which can supplement grain protein and improve its nutritional value. The content of essential fatty acid linoleic acid in soybean oil is as high as 50%, which is a high-quality edible oil. In addition, soybean also contains more calcium and thiamine, and riboflavin is also higher in plant foods.
Soybeans include soybeans, black beans and mung beans. Soybean is rich in high-quality protein, unsaturated fatty acids, calcium and B vitamins, which is the main source of high-quality protein in people's diet. The protein content of soybean is 35%-40%. Except methionine, the composition and proportion of other essential amino acids are similar to those of animal protein, and they are rich in lysine lacking in cereal protein, which is a natural ideal supplementary food for cereal protein. Soybean is rich in calcium, phosphorus, iron and B vitamins, higher than cereals, and contains a certain amount of carrots, vitamins and vitamin E. In addition, soybean also contains many healthy ingredients, such as soybean saponins, isoflavones, phytosterols, soybean oligosaccharides and so on.
3. Vegetables and fruits: It is an important part of people's diet and contains various nutrients needed by the human body. Its main characteristics are: high water content, low protein and fat content, but rich in vitamin C, carotene, inorganic salts and dietary fiber, which is the main source of these nutrients in people's diet. Vegetables are divided into dark color and light color, and the nutritional value of dark color is generally better than that of light color vegetables. Citrus is the most nutritious fruit, and the vitamin C content of many wild fruits such as Rosa roxburghii, Hippophae rhamnoides, Kiwi and Jujube is 20- 100 times higher than that of citrus and other fruits. In addition, vegetables and fruits also contain various organic acids, aromatic substances, pigments and other ingredients. Although these substances are not nutrients, they are of great significance to stimulate appetite, help digestion and enrich diet.
Vegetables are rich in water and low in energy, which are important sources of micronutrients, dietary fiber and natural antioxidants. Generally, the water content of fresh vegetables is 80% ~ 95%, and most of them are above 90%. Vegetables contain cellulose, hemicellulose, pectin, starch, sugar and so on, and most of them have low energy. Vegetables are also good sources of carrots, vitamins, vitamin B2, vitamin C, folic acid, calcium, phosphorus, potassium and iron.
Vegetables can be divided into dark vegetables and light vegetables, and the nutritional value of dark vegetables is generally better than light vegetables. Dark vegetables refer to dark green, red, orange and purplish red vegetables, which are rich in carotene, especially β-carotene, and are the main source of vitamin A. Dark vegetables also contain a variety of pigments, such as chlorophyll, lycopene, anthocyanins and other aromatic substances, which give vegetables special color, fragrance and taste and promote appetite.
4. Nutritional characteristics of fruits
Most fresh fruits contain 85% ~ 90% water, which is an important source of vitamins, minerals and dietary fiber in the diet. Red and yellow fruits, such as mango, papaya, hawthorn, apricot and so on. Carotene I and carotene content are high; Jujube, citrus and berries, such as kiwi fruit, blackcurrant and strawberry, have higher vitamin C content. Banana, longan and jujube have higher potassium content. Mature fruits generally contain more nutrients than immature fruits.