1'78 BIOCHEMICALLY IMPORTANT MINERAL ELEMENTS 



versus nonmetals in favor of the metals. The oxides, peroxides, hy- 

 droxides, carbonates, or nitrates of sodium, potassium, calcium, or 

 magnesium are suitable for this purpose. The peroxides or nitrates are 

 especially useful because they are also strong chemical oxidizing agents 

 and help to complete the ashing in a shorter time or at a lower tem- 

 perature. 



Once the ash has been obtained it is usually taken up in an acid solu- 

 tion such as nitric, the insoluble silica filtered off, and the solution tested 

 for metallic and nonmetallic ions by the usual methods of qualitative 

 analysis. 



Occurrence 



The amount of inorganic material contained in foodstuffs varies with 

 the material, and in the case of plants with the type of soil, fertilizer, 

 etc. Approximately 4.4 per cent of the total weight of the body consists 

 of inorganic compounds. The bones contain from 22 to 82 per cent, 

 whereas the muscles and the body fluids contain about 1 per cent. Plant 

 material varies in ash content from 1 to 10 per cent. More is contained 

 in the stems and leafy portions of the plants than in the seeds. 



Although the concentration of any element in a given food material 

 may vary markedly, depending upon the conditions under which it is 

 produced, the table given below and the tables in the Appendix afford 

 a fairly accurate estimate of the relative concentrations of these elements 

 in various foodstuffs. In Table &-1 note the low calcium content of 

 cereals in comparison with the large demands for this element in the 

 animal body. Observe that the milling process results in a concentra- 

 tion of the mineral elements in the bran and, hence, a depletion of the 

 same in the flour. 



Table 8-1 



Mineral composition of some typical foodstuffs 



(Fresh basis) 



percentage of: Ca Mg K Na P CI S Fe 



Wheat, whole 0.055 0.163 0.409 0.106 0.342 0.088 0.175 0.006 



Wheat, flour, white .021 .021 .137 .053 .096 .079 .155 .0012 



Wheat, bran 065 .420 1.25 .007 1.43 .042 .245 .014 



Corn meal 016 .084 .213 .039 .152 .146 .111 .0011 



Cabbage 054 .016 .217 .038 .031 .034 .074 .00066 



Turnips .042 .019 .193 .104 .032 .054 .048 .00061 



Cow's milk 123 .019 .129 .047 .088 .114 .031 .00024 



Animal body (Ox). 1.24 .030 .117 .089 .682 



More extensive tables are given in the Appendix. The table on trace 

 elements (p. 443) shows the small amounts contained in foodstuffs. Of 

 these elements iodine is the least abundant. It should be noted that 



