Walnut tree is an important woody oil-bearing fruit tree with high economic value, and its fruit is a food with high nutritional value.

The quality of walnuts and nuts is concerned by producers, operators, consumers and foreign trade departments. The quality of different nuts has different prices. According to the quality requirements, it can be divided into excellent products, first-class products and second-class products. Each grade requires that the nuts are fully mature, the shell surface is clean, the suture line is tight, there is no dew, moth, oil, mildew, odor and impurities, and the water content of nuts is ≤8%.