108 



THE PEANUT— THE UNPREDICTABLE LEGUME 



conclusions about the differences in mineral composition, because there 

 are practically no comparative analyses of different types of plants when 

 grown under controlled or known conditions. 



Seed 



The mineral composition of mature seed of peanuts is relatively con- 

 stant for a given variety. The nitrogen (protein) content of seed of the 

 Spanish type is reported (79) to be higher than that of the Virginia pea- 

 nut. However, while the data ( 5, 30, 33, 43, 91 ) of nitrogen content as 

 well as that of other elements indicate varietal differences, it is not known 

 whether such differences are significant. Data of mineral composition of 

 seed as compiled from several sources (26, 33, 43, 48, 83) are given in 

 tables 4 and 5. 



Table 5.- 



-Range in Percentage of Inorganic Constituents in the Peanut 

 Kernel, After Hoffpauir et al. (33, 43) 



Potassium . 

 Calcium. . . 

 Magnesium 

 Phosphorus 

 Sulfur 



.68-. 89 

 .02-. 08 

 .09-. 34 

 .25-. 66 

 .19-. 24 



Zinc 



Manganese. . 



Iron 



Copper 



Boron 



Molybdenum 



.0017-. 08 

 .0008-. OS 

 .0018-. 10 

 .0007-. 03 

 .0026-. OS 

 .0008-. 003 



Hoffpauir and Guthrie (43) report that 87 percent of the nitrogen 

 of the peanut seed is present as arachin and conarachin. Their data indi- 

 cate that the amino acids usually considered essential for animal growth 

 are present in the seed. 



The average percent oil content of seed of control treatments from 

 results of Middleton et al. (54) are as follows: 48.5, 49.1, 50.1 and 51.8 

 for Virginia Bunch, North Carolina Bunch, Spanish 2B, and White 

 Spanish, respectively. Others (30, 43, 91) have reported results indicat- 

 ing some varietal differences in oil content. Several workers (30, 54, 62, 

 74) have shown that the oil content of mature seed is much higher than 

 that of shrivels and immature seed. Those data suggest that an accurate 

 description of seed samples should be included when oil analyses are 

 reported. 



The composition of oil from Spanish seed (33, 43) is given in table 6. 



Peanut oil is nondrying, edible, and has a specific gravity of 0.917- 

 0.920, refractive index of 1.467-1.470, saponification number of 186- 

 194, and iodine number of 85-100 (33, 43, 93). 



There is little change in the firee fatty acid content or iodine number 



