As one of the famous nuts, walnut is rich in high protein. However, not all walnuts are full of shell kernel, walnuts before the official market sale, also need to be sorted and screened. And there are some standards about the classification of different grade of walnut.
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Criteria for walnut grading
In fact, the classification of all nut products is generally based on size, weight, shape, color and other aspects. Although different countries have slightly different classification standards for nuts, they are similar in many aspects.
Common walnut grading terms and definitions
- Superior Walnut: Walnut cultivated by adopting superior varieties and through asexual reproduction.
- Solid walnut: Walnut cultivated by seed reproduction.
- Three-path means: The arithmetic mean of the longitudinal, transverse, and lateral diameters of a walnut, usually measured in mm.
- Yield: The percentage of the weight of walnut kernels in the total weight of walnuts in the shell.
- Rate of broken fruit: Percentage of the total number of walnuts measured by the number of broken shells.
- Black spot rate: The percentage of the number of walnuts with black spots caused by residual epidermis and pests on the walnut shell.
Standard for super grade of walnut
The walnut of the high quality grade is uniform in size and shape, with a natural yellow-white shell. The walnut kernel is full, the color is yellow-white, and the astringent taste is light.
The kernel rate was ≥53%, the damaged fruit rate was ≤0.1, and the black spot fruit rate was 0.
How to grade walnut treatment
Since the first requirement of high-quality walnuts is uniform size, walnut-size screening is the first step in walnut grading.
For walnut grading, can be completed through the nut grading machine processing. Grading machine is mainly through the size of different screen hole diameter to complete the grading of walnut, the machine can be set according to the actual requirements of screening grading customers to different levels, generally 3-5 level.
A brief introduction of walnut grader
Walnut grading machines widely used in the nut processing industry. In addition to walnut, but also can handle cashew, hazelnut, and other nuts.
The inside of the machine is in the shape of a drum. After the machine starts, then the drum will start to rotate at a constant speed. The materials that need to be graded will be poured from one end. And the materials will pass through the small and large sieve holes through the rotation of the drum, thus achieving the grading effect of materials.