THE M M A I > AM I A NUT IN HAWAII 
23 
indications are that most of the roucrh-shell trees will be either elimi- 
nated or top worked. 
The methods used in this study were devised primarily to evaluate 
the macadamia as a shelled processed kernel. As finally adopted, a 
sample is carried through the process of sizing the unshelled nut to 
eliminate small sizes, shelling, and specific-gravity grading to elimi- 
nate kernels of poor quality. The resultant quality ratio gives as a 
single value the pounds of nuts as received to produce 1 pound of 
grade 1 kernel As such, the method has proved useful both in the 
experimental phases and as a commercial procedure. 
SUMMARY 
This bulletin reports investigations by the Hawaii Agricultural 
Experiment Station on development of methods for evaluating the 
macadamia nut from the standpoint, of a shelled roasted product, 
and application of these methods to tin 4 evaluation of nuts from com- 
mercial orchards throughout the Territory. 
It was found that the specific gravity of the macadamia kernel has 
a very high negative correlation with the percent oil ( — 0.985 for the 
rough-shell type and —0.979 for the smooth-shell type). The 
method thus serves as a rapid method for determining the oil content. 
Specific gravity is likew ise related to the roasting quality of maca- 
damia kernels. It has been found that kernels may be graded as to 
roasting qualities as follows: Grade 1 specific gravity less than 1, 
grade 2 — specific gravity between 1.000 and 1 .02"), and grade 3— - 
specific gravity greater than 1.025. Only grade 1 kernels are used in 
present commercial packs. 
A single value known as quality ratio was developed which desig- 
nates the pounds of unshelled nuts as received to produce 1 pound of 
grade 1 kernels. 
Individual seedling trees show great variation in nut characteris- 
tics, the large number of bearing trees furnishes ample material for 
selection as to size, percent kernel, and quality of kernel, as well as 
total yield. 
There is evidence of significant difference in kernel characteristics 
between the rough-shell and smooth-shell types of macadamia nuts. 
The latter is the better type as judged by kernel quality and adapta- 
tion to the roasted pack. 
( Commercial shipments of unshelled nuts received at the factory show- 
marked difference in quality ratio. It is believed that the purchase 
price of the nuts should be based on the quality ratio. 
LITERATI RE ( ITED 
(1) Camp, A. P. 
11930). avocado maturity studies. Fla. Agr. Expt. Sta. Rept. 1929-30: 
79-81. 
(2) Coleman, I). A., and Fellows, H. C. 
1927. oil content of flaxseed, with comparisons of tests for de- 
termining oil content. U. S. Dept. Agr. Bull. 1471, 35 pp., 
illus. 
(3) Drake, N. F. 
1930. a method for grading black w alnuts. Ainer. Nut Jour. 32 (2): 28. 
(4) Foth, G. 
1907. DIE BEST1MMUNG DES STARKE GEHALTES DER KARTOFFELN NACH DEM 
-ikzifischen gewicht. Ztschr. Spiritusindus. [Berlin] 30: 
217-218. [Abstract by J. F. B. in Jour. Soc. Chem. Indus. 26: 
705. 19071 
