Mechanical peeling method is mainly carried out by walnut peeling cleaner. At present, peeling machines commonly used in the market are mainly divided into scraping type, cutting type, extrusion type and impact type according to the stress situation. Among the four peelers, scraper is the first choice, because it has strong adaptability, but low efficiency, and the contradiction between the net rate of walnuts and the total crushing rate is more prominent.

2, frozen peeling method

This method is to freeze walnut green peel at low temperature, and then melt and peel it. The specific operation process is as follows: removing pests and diseases and fruits with no commercial value, and then freezing at low temperature in the cold storage at -5℃ to -20℃. When the green husk is completely frozen, the temperature rises above 0℃, and then the green husk is removed manually or mechanically. However, in practical application, this method is often combined with composting, that is, the heated fruit is piled indoors or outdoors for 8- 12 hours and let it fall off naturally.

3, heap retting peeling method

This method is simple in operation, low in equipment requirements and widely used. Specifically, after harvesting, the walnuts are piled into a pile of 50cm, and a covering of about 10cm is laid on it for 4-6 days. When the green husk is shelled or cracked to about 50%, knock them off with a wooden stick or other methods. However, attention should be paid to the composting time to prevent the bacteria and molds produced by long-term composting of walnuts from invading the interior of walnuts, polluting the walnuts, leading to the decline of the commercial properties of walnuts and reducing the economic benefits of growers.