The first thing is to weigh. To grasp the general principle of "roly-poly", grapefruits that are small in appearance and heavy in weight contain more water. Generally, grapefruits that weigh about 3 kilograms in the palm of your hand are good. You can also select high-quality grapefruit based on appearance, specific gravity, feel, etc. If the grapefruit skin is fine and clean, the oil cells on the surface are translucent, and the color is light yellow or orange, it means the grapefruit is highly mature and juicy and sweet. The thickness of the grapefruit peel determines the sweetness and moisture of the grapefruit. For grapefruits of the same size, choose heavier ones. Secondly, you should feel the smoothness of the grapefruit peel with your hands. If it is not easy to press when pressing hard, it means the capsule is tight and of good quality. If the grapefruit is large in size and light in weight, the grapefruit will have thick skin and little meat, and will not taste good. In addition, grapefruit has a wide tip and a flat bottom. It is better to choose a grapefruit with a short neck and a flat bottom. You can also squeeze it with your hands. If it is not easy to press, it means the flesh is firm and the meat is sweet and tender. The standard type of grapefruit is a pointed top and a wide bottom. Among them, it is better to choose grapefruits with an oblate shape and a short neck (a flat bottom is better). This is because grapefruits with long necks have less flesh and appear to have more skin. Nutritional analysis 1. Pomelo contains potassium, a natural trace element necessary for patients with hypertension, and contains almost no sodium. Therefore, it is the best therapeutic fruit for patients with cardiovascular and cerebrovascular diseases and kidney diseases; 2. Pomelo contains a large amount of vitamin C. It can reduce cholesterol in the blood; 3. The pectin in grapefruit can not only reduce the level of low-density lipoprotein, but also reduce the damage to the arterial wall; 4. Pomelo also has the effect of strengthening the body, which helps the body absorb calcium and calcium more easily. Iron and the natural folic acid contained in it can prevent anemia symptoms and promote fetal development for pregnant women; 6. Fresh grapefruit meat contains chromium, a component similar to insulin, which can lower blood sugar. It can be consumed by the general population. 1. People suffering from stomach problems, indigestion, chronic bronchitis, cough, phlegm and asthma, especially patients with heart, brain and kidney disease; 2. People with spleen deficiency and loose stools should eat with caution. Therapeutic effects: Pulp: sweet and sour, cold in nature, non-toxic, has the effects of strengthening the spleen, relieving cough, and relieving hangover; Pomelo peel: bitter and sweet, warm in nature, has the effects of reducing phlegm, relieving cough, regulating qi, and relieving pain; Indications: Cough and asthma, Qi stagnation, chest tightness, abdominal cold pain, stagnation of food, hernia, etc. The taste of freshly picked grapefruit is not the best, so it is best to keep it indoors for a few days. Generally, after two weeks, when the water in the grapefruit gradually evaporates, the taste will become sweeter and sweeter.