WORLD HEALTH ORGANIZATION
WHO Food Additives Series 1972, No. 1
TOXICOLOGICAL EVALUATION OF SOME
ENZYMES, MODIFIED STARCHES AND
CERTAIN OTHER SUBSTANCES
The evaluations contained in this publication were prepared by the
Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
16-24 June 19711
World Health Organization
Geneva
1972
1 Fifteenth Report of the Joint FAO/WHO Expert Committee on Food
Additives, Wld Hlth Org. techn. Rep. Ser., 1972, No. 488; FAO
Nutrition Meetings Report Series, 1972, No. 50.
The monographs contained in the present volume are also issued by the
Food and Agriculture Organization of the United Nations, Rome, as FAO
Nutrition Meetings Report Series, No. 50A
(c) FAO and WHO 1972
ACETYLATED DISTARCH ADIPATE
Modification is carried out by the use of 8 per cent. acetic anhydride
and a maximum of 0.12 per cent. adipic acid, the latter acting as
cross-linking agent. The maximum number of acetyl groups introduced
is 2.5 per cent. The number of adipic cross-links does not exceed
more than 1 in about 1000 glucopyranose units, or not more than 0.09
per cent. adipyl groups introduced in the starch.
Biological data
Biological 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 per cent. (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 per cent. of the C14 activity of the free adipic
acid was recovered in the respired air; 5.8 per cent. appeared in the
urine while none was detected in the faeces, in the gastro-intestinal
tract or in the carcass. 70.5 per cent. of the C14 activity of the
esterified adipic acid appeared in the respired air and 7.2 per cent.
in the urine; 24.5 per cent. 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 per cent.
adipic anhydride and 5.5 per cent. 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).
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 per cent. 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 per cent. adipic acid and 10.5 per
cent. acetic anhydride resulting in 3.1 per cent. of acetyl groups
being present (Oser, 1964).
Long-term studies
None available.
Comments
A study with C14-labelled material showed that the reacted adipic
acid entered the metabolic pool more slowly but followed the normal
pathways for 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 the group of modified starches considered suggests that caecal
enlargement without associated histopathological changes is of little
toxicological significance. The observed decrease in growth rate at
the dietary level used appears to be related to the use of an
extremely high level. No longterm studies are available but the
collateral evidence from starch acetate and acetylated distarch
phosphate indicates that acetylation causes no adverse effects.
EVALUATION
Temporarily not limited.*
Further tests required by 1973
Histological report to complete the long-term and reproduction studies
in the rat on starch acetate.
Histological report to complete the reproduction study in the rat on
acetylated distarch phosphate.
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
* Except for good manufacturing practice.
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 Also:
Toxicological Abbreviations
Acetylated distarch adipate (FAO Nutrition Meetings Report Series 46a)
Acetylated distarch adipate (WHO Food Additives Series 5)
Acetylated distarch adipate (WHO Food Additives Series 17)
ACETYLATED DISTARCH ADIPATE (JECFA Evaluation)