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
Geneva
1974
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.
DISTARCH GLYCEROL
Explanation
Treatment with epichlorhydrin under alkaline conditions up to 0.3%
tends to produce cross-linking at a rate of one glycerol diether
linkage per 220 - glycopyranose units.
BIOLOGICAL DATA
BIOCHEMICAL ASPECTS
Much evidence in the literature points to etherified starches
being somewhat resistant to enzymic degradation. Probably small
fragments containing the ether linkage will remain and will not be
absorbed readily. Any material absorbed is likely to be excreted by
the kidney. Ne direct experimental evidence exists for this particular
hypothesis (French, 1960). The metabolic fate of methyl-glucose is
cited as collateral evidence. Although methylglucose is absorbed by
rats (Sols, 1956) no demethylation is believed to occur (Csáky &
Wilson, 1956) and excretion is essentially quantitative (Csáky &
Glenn, 1957). The in vitro digestibility by amyloglucosidase of
distarch glycerol (0.3% epichlorhydrin) was shown to be 98.3% of that
of unmodified starch (Kruger, 1970). The caloric values of two
starches treated at levels of 0.07% and 0.50% epichlorhydrin were
estimated in groups of 10 weanling male rats by comparing the weight
gain obtained after feeding for 28 days a basal diet supplemented with
3 g of each starch against a dose-response curve obtained by feeding
daily sucrose supplements of 0, 1.5 g, 3 g, 4.5 g and 6 g equivalent
to approximately 0, 6, 12, 18 and 24 calories. Distarch glycerols were
only slightly lower in caloric value than unmodified starch, the
differences not being significant (Oser, 1961).
TOXICOLOGICAL STUDIES
Short-term studies
Rat
Three groups of 10 male and 10 female rats were fed for 90 days
unmodified starch or starch treated with 0.07% or 0.50% epichlorhydrin
at 71% of their diet. Growth rate, appearance, behaviour and food
intake were similar in all three groups. Haematological investigations
showed no abnormalities related to the feeding of modified starches.
Non-protein nitrogen blood levels and blood sugar levels remained
normal in all groups. The weights of all major organs were normal and
no abnormal gross or histopathological changes related to treatment
were seen (Oser, 1961).
Long-term studies
None available.
Comments:
The feeding studies with rats show that the modified starch is
well utilized. The available evidence for the group of modified
starches considered indicate that caecal enlargement without
associated histopathological changes is without toxicological
significance. The short-term rat study shows no adverse effects at the
high dietary level used. No long-term study on this modified starch is
available and collateral evidence from the long-term and reproduction
studies with hydroxypropyl distarch glycerol, a more highly modified
starch, indicates that the glycerol linkage is causing no adverse
effects.
EVALUATION
Estimate of acceptable daily intake for man
Not limited.*
REFERENCES
Csáky, T. Z. & Glenn, J. E. (1957) Amer. J. Physiol., 188. 159
Csáky, T. Z. & Wilson, J. E. (1956) Biochim. Biophys. Acta., 22, 185
French, D. (1960) Unpublished report
Kruger, L. (1970) Unpublished reports Nos 405 & 406 submitted by
National Starch and Chemical Corporation
Oser, B. L. (1961) Unpublished report of Food and Drug Research
Laboratories Inc., submitted by National Starch and Chemical
Corporation
Sols, A. (1956) Rev. esp. Fisiol., 12, 17
* See relevant paragraph in the seventeenth report, pages 10-11