INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
TOXICOLOGICAL EVALUATION OF SOME
FOOD COLOURS, EMULSIFIERS, STABILIZERS,
ANTI-CAKING AGENTS AND CERTAIN
FAO Nutrition Meetings Report Series
No. 46A WHO/FOOD ADD/70.36
The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
27 May - 4 June 19691
Food and Agriculture Organization of the United Nations
World Health Organization
1 Thirteenth report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, in press;
Wld Hlth Org. techn. Rep. Ser., in press.
Esterification is achieved by using either acetic anhydride (up to 8
per cent.) or vinyl acetate (up to 7.5 per cent.). A maximum of 2.5
per cent. acetyl groups is introduced corresponding to a maximum
degree of substitution of 0.1.
The digestibility of acetylated starches was measured by the
biochemical oxygen demand of incubated samples. As the acetyl contents
increased so the BOD values decreased and, in parallel, the
digestibility. Starch acetates containing 2.5 per cent. acetyl groups
are only 93.7 per cent. as digestible as native starch (Turner, 1961).
Digestibility by fungal amyloglucosidase was shown to be 80.5 per
cent. of that of native starch (Turner, 1961). Caloric values were
determined in groups of 10 male rats fed 4 weeks on a diet
supplemented with graded doses of 0, 1.5 g, 3.0 g, 4.5 g and 6.0 g
dextrose (equivalent to O, 6, 12, 18 and 24 calories). The dose
response curve was used to estimate the caloric value of supplements
of 3 g and 4.5 g of acetylated (1.8 per cent. acetyl) or native
starch. No significant difference was found between the starch samples
with regard to caloric value (Oser, 1961).
Rat. Groups of 10 male rats were fed for 28 days diets containing 60
per cent. of various starch acetates (the degree of acetylation varied
from 0, 1.24 per cent., 2 per cent., 2.56 per cent. to 3.25 per
cent.). Weight gain was reduced in groups receiving starch acetates
with more than 2 per cent. acetylation but feed efficiency remained
unaffected. Diarrhoea occurred at 2 per cent. and higher degrees of
acetylation and there was noticeable caecal enlargement at the same
levels. No tissue damage or inflammation were noted in association
with the diarrhoea (Turner, 1961). In another experiment potato starch
acetates (acetylated to 1.36 per cent.) was fed for 13 weeks to groups
of 10 male and 10 female rats at levels of 5 per cent., 15 per cent.
and 45 per cent. of the diet. The 5 per cent. level was fed for only 4
weeks. No animal died. Growth rates and haematological findings were
not significantly affected. The relative weights of liver, kidney,
adrenal, pituitary and thyroid showed some significant differences
compared with controls, being generally lower except for male
thyroids. Male caecal weights were higher than controls and distended
caecal were seen at the 15 per cent. and 45 per cent. dietary levels.
No other histopathological changes due to starch acetate were seen
(Feron et al., 1967).
Commercial acetylation processes introduce considerable modifications
in the starch molecule. An increasing degree of acetylation reduces
in vitro enzymatic digestibility and leads to diarrhoea and caecal
enlargement when the product is fed at high dietary levels. The
short-term study in rats was inadequately designed. However, a
no-effect level for the study can be derived. In view of the
comparatively large modification in the starch molecule it would be
desirable to carry out life-span studies in one species and metabolic
studies in man.
Level causing no toxicological effects in the rat
Five per cent. (= 50 000 ppm) in the diet equivalent to 2500 mg/kg
Estimate of acceptable daily intake for man
Temporary acceptance mg/kg body weight
Further work required by June 1972
Adequate 90-day studies in 2 species (one a non-rodent mammal).
Feron, V.J., Til, H. P. and de Groot, A. P., (1967) Report No. R2329
by Centraal Instituut voor voedingsondrzoek (TNO)
Oser, M., (1961), Unpublished report No. 79868b & c by Food and Drug
Research Laboratories Inc., 20 April 1961. Submitted by National
Starch and Chem. Corp.
Turner, A. W., (1961) Unpublished report to Avebe, 17 October 1961.
Submitted by Assoc. Amidonneries de Mais.