A Detailed Guide to Making Walnut Oil and Walnut Powder

  (1) Raw material preparation: walnut kernels.

  (2) Process flow: walnut kernels → low-temperature oil extraction → walnut cake → crushing → flaking → walnut flakes → extraction tank → desolventizing → low-temperature phase → ultrafine grinding → walnut protein powder.

  (3) Key operating points

  Pre-pressing: use a hydraulic oil press for pressing, controlling the pressure at 4~10 megapascals; the pressure should be raised gradually and frequently, and must not be raised too high at once, otherwise the oil is likely to spray out in a slurry form or the oil flow channels between the oil-bearing material become blocked and contract, and the oil yield will instead decrease.

  Crushing: after pressing, the walnut kernels have already had their structure changed by the external force; processing them further with a crusher to break them into small pieces facilitates flaking.

  Flaking: the rolled walnut flakes should have a certain toughness and low powder content, making them suitable for extraction.

  Low-temperature solvent extraction: the extractor should be of the tank-group type, with a material-to-solvent ratio of 1 : 1. The resulting walnut oil should be light yellow, with residual solvent in the oil below 50 mg/kg; the meal is white, and the vitamins, bioactive enzymes and so on in the crude oil and the phase are basically not destroyed.

Pictured: walnut powder

  The above describes the common processing forms of walnuts. In addition, walnuts have a long history of use in dishes and snacks in China, mostly traditional home-style preparations made simply by the urban and rural people in walnut-producing areas, such as: crispy fried walnuts, eight-treasure stuffed walnuts, curried walnuts, snow-coated walnuts, walnut soup, walnut paste, pork stewed with walnuts, or used as dumpling filling, pancake filling, and so on. Of course, some have also entered the menus of restaurants and hotels, such as: the famous dish diced chicken with walnut kernels at Beijing Hotel, Shanghai-style walnut chicken and walnut tofu, Jilin-style tomato walnut chicken rolls, Shaanxi-style braised button mushrooms with walnuts, and so on. There are also dishes introduced from abroad, such as: Iranian walnut meatballs, walnut fish in Western cuisine, and so on. Whether used as a main ingredient or an auxiliary ingredient, walnuts are highly favored by everyone for their unique flavor and rich nutritional value.