Toxicological evaluation of some food
additives including anticaking agents,
antimicrobials, antioxidants, emulsifiers
and thickening agents
WHO FOOD ADDITIVES SERIES NO. 5
The evaluations contained in this publication
were prepared by the Joint FAO/WHO Expert
Committee on Food Additives which met in Geneva,
25 June - 4 July 19731
World Health Organization
1 Seventeenth Report of the Joint FAO/WHO Expert Committee on
Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 539;
FAO Nutrition Meetings Report Series, 1974, No. 53.
These starches contain phosphoric ester groups, mainly attached
to C-6 and to a lesser extent to C-2 and C-3 and of the glucopyranose
units (Gramera et al., 1966). They are made by the use of alkali
orthophosphates, phosphoric acid, or alkali tripolyphosphate.
In vitro enzymatic hydrolysis of monostarch phosphate by wheat
alpha-amylase was compared with unmodified wheat starch. No difference
was noted in the rate of production of reducing substances. The
metabolic behaviour of the phosphate radical in starch phosphate was
studied in vivo by comparing the distribution of p32 after oral
administration of labelled starch phosphate to rats, with that from
either labelled orthophosphate or pyrophosphate. The percentage
activity excreted in urine and faeces over 48 hours as well as the
percentage activity retained in liver, kidney, blood plasma and bone
showed no significant difference for the three types of phosphate
examined. The phosphate moiety of starch phosphate probably behaves
metabolically like any other ionic phosphate (Laboratories of
International Minerals & Chemical Co., 1955).
An adequate metabolic study has shown that the modification does
not affect the digestibility of this starch. Whatever the manner of
attachment of the phosphate groups may be, their metabolic disposition
after digestion follows the same pathways as free orthophosphate or
pyrophosphate. This material is not to be regarded as toxicologically
different from native starch of the same botanical origin provided the
phosphate content is limited.
Estimate of acceptable daily intake for man
* See relevant paragraph in the seventeenth report, pages 10-11.
Gramera, R. E., Heerema, J. & Parrish, F. W. (1966) Cereal Chem., 43,
Laboratories of International Minerals and Chemical Corporation (1955)
Unpublished report to American Maize Products Co.