Natural sour food is mainly fruit, and these fresh sour tastes are brought by the unique organic acids in fruits. The most abundant acids in fruits are citric acid and malic acid. Citric acid is mainly distributed in citrus fruits, strawberries, pineapples and pomegranate. Malic acid is mainly distributed in stone fruits such as apples, and fruits such as cherries, apricots and peaches contain citric acid and malic acid. These organic acids play an important role in regulating body fluid balance. Vitamin C also has a slight sour taste, which is more stable in acidic environment, so many fruits rich in vitamin C have a sour taste. Sweetness in sweets is provided by various types of sugar. These relatively simple carbohydrates are the cleanest and most direct source of energy. Some amino acids also have sweet taste, such as glycine, alanine, serine, lysine, methionine, hydroxyproline and so on. These amino acids are an important part of protein synthesis and play an important role in human growth and development. The taste of bitter food is mostly produced by plant compounds in food, mostly polyphenols. Recent studies have found that these substances are strong antioxidants, which have the effects of inhibiting coronary heart disease and atherosclerosis, scavenging free radicals, anticancer and anti-inflammatory. Spicy taste in spicy food is generally provided by capsaicin or volatile sulfide. Studies have shown that capsaicin has excellent analgesic effect, and can also improve metabolism, burn fat and lose weight. The spicy taste in garlic, onion and other foods is produced by volatile sulfides. These sulfides have strong bactericidal and anti-inflammatory effects, and can play a health care role in preventing influenza and promoting metabolism.