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.
MODIFIED STARCHES AND DEXTRINS
Explanation
These substances have been evaluated for acceptable daily intake
by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
Refs Nos 20 and 27) in 1969 and 1971.
Since the previous evaluations, additional data have become
available and are summarized and discussed in the following
monographs. The previously published monographs have been either
revised or expanded and are reproduced in their entirety below.
ACETYLATED DISTARCH ADIPATE
Explanation
Modification is carried out by the use of 8% acetic anhydride and
a maximum of 0.12% adipic acid, the latter acting as cross-linking
agent. The maximum number of acetyl groups introduced is 2.5%. The
number of adipic cross-links does not exceed more than 1 in about 1000
glucopyranose units, or not more than 0.09% adipyl groups introduced
in the starch.
BIOLOGICAL DATA
BIOCHEMICAL ASPECTS
In vitro studies with pancreatin have shown that only the
acetate ester bond splits easily while the adipic acid ester linkages
are not attacked. No free adipic acid could be demonstrated in the
hydrolysate (Morgareidge, 1959a). In vitro digestion with
amyloglucosidase of acetylated distarch adipate showed a digestibility
of 98.3% (Kruger, 1970). The metabolic fate of adipate-modified
starches was investigated in male rats in vivo using adipic acid
labelled at C1 and C6 with C14. The rate of appearance of 14CO2 was
compared between starch modified with 1,6 - C14 adipic acid. Starch
adipate is absorbed and/or metabolized more slowly as evidenced by the
delayed appearance of 14CO2 in the respired air. 99.3% of the C14
activity of the free adipic acid was recovered in the respired air;
5.8% appeared in the urine while none was detected in the faeces, in
the gastrointestinal tract or in the carcass. 70.5% of the C14
activity of the esterified adipic acid appeared in the respired air
and 7.2% in the urine; 24.5% was found in the faeces. No activity
appeared in the carcass (Morgareidge, 1959b). The caloric equivalent
of the modified starch was determined in groups of 10 male rats fed
for 28 days on a basal diet containing either 1.5 or 3.0 g of starch
supplements. The modified starch had been treated with 0.2% adipic
anhydride and 5.5% acetic anhydride. Native starch was used as
control. Caloric values were determined from a dose/response curve
obtained by the use of 0, 0.75 g, 1.5 g, 3.0 g and 4.5 g of sucrose
supplements equivalent to 0, 3, 6, 12 and 18 calories per day. There
was no difference in caloric value as between the modified and
unmodified starches (Oser, 1961).
TOXICOLOGICAL STUDIES
Short-term studies
Rat
A 90-day feeding study was carried out in groups of 15 male and
10 female rats at a dietary level of 50% modified or unmodified
starch. The growth rate of males was significantly lower in the test
group and the full and empty caecal weights of both sexes were
significantly greater in rats fed the treated starch. All rats
survived the test period and no differences were observed between the
groups in respect of liver and kidney weights, haematology, blood
chemistry, urinalysis, gross and histopathology. The modified starch
used had been treated with 0.12% adipic acid and 10.5% acetic
anhydride resulting in 3.1% of acetyl groups being present (Oser,
1964).
Long-term studies
None available.
Comments:
A study with 14C-labelled material in the rat showed that the
adipic acid moiety entered the metabolic pool more slowly but followed
the normal pathways for free adipic acid. No retention of label was
found in the carcass. Short-term feeding studies with rats at a high
dietary level showed no significant pathological changes. The
available evidence for modified starches as a group suggests that
caecal enlargement without associated histopathological changes is
without toxicological significance. The observed decrease in growth
rate with a high dietary level was considered to be due to nutritional
imbalance. No long-term studies are available, but the evidence from
studies with the related starch acetate and acetylated distarch
phosphate, indicate that acetylation does not yield substances
exhibiting adverse effects.
EVALUATION
Estimate of acceptable daily intake for man
Not limited.*
REFERENCES
Kruger, L. (1970) Unpublished reports Nos 405 & 406 submitted by
National Starch and Chemical Corporation
Morgareidge, K. (1959a) Unpublished report No. 78522 of Food and Drugs
Research Laboratories Inc., submitted by National Starch and
Chemical Corporation
Morgareidge, K. (1959b) Unpublished report No. 79408 of Food and Drugs
Research Laboratories Inc., submitted by National Starch and
Chemical Corporation
Oser, M. (1961) Report No. 81776 of Food and Drugs Research
Laboratories Inc., submitted by National Starch and Chemical
Corporation
Oser, B. L. (1964) Report No. 85555 of Food and Drugs Research
Laboratories Inc., submitted by National Starch and Chemical
Corporation
* See relevant paragraph in the seventeenth report, pages 10-11.
See Also:
Toxicological Abbreviations
Acetylated distarch adipate (FAO Nutrition Meetings Report Series 46a)
Acetylated distarch adipate (WHO Food Additives Series 1)
Acetylated distarch adipate (WHO Food Additives Series 17)
ACETYLATED DISTARCH ADIPATE (JECFA Evaluation)