The cracking quality of the nuts from the trees in this study was tested on a random sample of nuts from each crop that was collected and brought back to Norris. The nuts of each sample were weighed and the average nut weight computed. The nuts were then cracked in a hand-cracking machine, and kernels that could be extracted with the fingers were removed and weighed.[13] From this weight was computed the first-crack marketable kernel percentage. The nuts that still contained kernels were recracked and the remaining kernel removed. All kernels, including crumbs, were then weighed in order to compute the total kernel weight and kernel percentage. Finally, all of the quarters extracted were counted, and the average number of quarters was computed. Kernels recovered at first crack and the average number of quarters extracted indicate the relative ease of extraction of kernels.
Cracking quality of walnuts for individual sample trees averaged by crop years are presented in Table 1. Nuts of all crops collected from four trees, 57, 58, 60, and 139, were shriveled or abnormal, and afforded no test of nut quality during the six-year period. Thus, nut quality data, based on 440 nut crop samples, are complete for 128 of the 132 sample trees. From this study, the average common black walnut in the Tennessee Valley has a nut weight of 17 grams, a kernel weight of 3.3 grams, a total kernel content of 20 per cent, a marketable kernel recovery at first crack of 17 per cent, and a quarter recovery of unbroken quarters averaging 1.8.
[Footnote 13: The kernels were extracted over a 6-mesh wire screen. In commercial cracking, kernel pieces passing through this type of screen are not marketable as kernels.]
Table I—Yield of Nuts and Kernels, and Cracking Quality of Nuts from 132 Sample Trees of Common Black Walnut in the Tennessee Valley
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Tree
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Diameter
at 4-1/2 ______________________________________________________
Sample ft.
number av. yr. 1940 1941 1942 1943 1944 1945 Av. yr.
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inches pounds pounds pounds pounds pounds pounds pounds 1 20.4 27 16 2 95 5 3 25 2 14.9 43 43 26 45 42 23 38 3 9.3 22 12 8 22 6 29 17 5 11.2 54 0 61 0 33 7 26 6 13.6 28 1 72 0 16 1 20 8 13.2 50 28 23 41 76 45 44
9 13.2 36 50 40 28 33 7 32 10 22.9 29 25 0 0 6 15 12 11 6.1 2 4 12 2 4 1 4 12 17.4 110 18 128 40 100 49 74 13 14.5 98 5 83 50 46 128 68 14 12.2 1 0 12 3 2 98 19
15 11.6 38 46 44 106 0 63 50 16 15.7 130 0 106 25 135 33 72 17 12.0 1 66 4 100 2 61 39 18 7.8 20 0 40 21 33 4 20 25 8.6 13 0 82 0 0 0 16 26 20.7 0 36 46 90 0 67 46