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
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
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 68-81 per
cent. of that of native starch (Turner, 1961; Kruger, 1970). The
digestibility of starch acetate (containing 1.98 per cent. acetyl
groups by pancreatin and porcine mucosal enzymes was found to be 90
per cent. of that of the unmodified starch (Leegwater, 1971). Caloric
value was determined in groups of 10 male rats fed for 4 weeks a diet
supplemented with graded doses of 0, 1.5 g, 3.0 g, 4.5 g and 6.0 g
dextrose (equivalent to 0, 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).
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, 2, 2.56 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
In another experiment potato starch acetate (acetylated to 1.36 per
cent.) was fed for 13 weeks to groups of 10 male and 10 female rats at
levels of 5, 15 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 caeca were seen at the 15 per cent. and 45 per
cent. dietary levels. No histopathological changes due to starch
acetate were seen (Feron et al., 1967).
In a further experiment starch acetate (acetylated to 1.98 per cent.)
was fed to groups of 10 male and 10 female rats for 8 weeks at dietary
levels of 25 per cent. and 50 per cent. No effects were noted on
growth and body-weight. Water content of faeces and faecal
production, as measured by dry matter content, showed no consistent
effects but there was a tendency towards increased faecal dry matter
at the 50 per cent. dietary level in both sexes. No diarrhoea was
observed at any dietary level. Caecal weight and caecal enlargement
occurred in a dose-related manner in all treatment groups. However,
histological examination revealed no abnormality of the caeca examined
(de Groot & Spanjers, 1970).
Twelve volunteers consumed on each of 4 consecutive days 60 g starch
acetate with 1.98 per cent. acetyl content. No effect was noted on
frequency and amount of faeces, faecal water or lactic acid content.
No other adverse effects were noticed (Pieters et al., 1971).
Groups of 30 male and 30 female weanling rats were fed on diets
containing 0, 5, 10 and 30 per cent. of starch acetate (acetylated to
1.98 per cent.) for 2 years. No significant differences were observed
with respect to behaviour, general health and mortality. Growth and
food consumption were essentially similar to those of the controls.
Production of faeces during weeks 11 and 12 showed no dose-related
differences among the various groups. Haematology, serum chemistry
and serum enzymes as well as urinalysis showed no effects related to
the administration of the test material. Among organ weights only the
caecal weight of male rats showed a dose-related increase at 10 per
cent. and higher levels and the caecal weight of female rats was
increased at the 30 per cent. level compared with controls. No other
significant changes were noted which could be ascribed to the test
substance. The histological examination is still incomplete (Til et
A three generation study was performed using 5 males and 10 females
for the P generation and 10 males and 20 females of the F1b and
F2b to produce successive generations by mating at week 12 and 20
after weaning. The F3b generation was kept for 3 weeks after
weaning and then sacrificed for histopathological study. The P,
F1b and F2b parents were used for determination of
implantation sites. The test material, fed at 10 per cent. of the
diet consisted of starch modified with 5 per cent. acetic anhydride
(degree of substitutions 0.079). No adverse effects were noted
regarding health, behaviour, mortality, body-weights, fertility,
litter size, resorption quotient, weaning weight of pups or mortality
of young. Caecal weights were increased. Gross pathology of the
F3b generation revealed that kidney weights in females differed
in a statistically significant way from controls but histopathology
is still underway (Til et al., 1971b).
Groups of 10 male and 10 female rats were given 25 per cent. and 50
per cent. of starch acetate (acetylated to 1.98 per cent.) in a low
residue diet for 7 days. Thereafter 4 per cent. cellulose was added
for a further 3 days. Body-weights were slightly reduced in both
sexes at the 50 per cent. level after 7 days. Faecal dry matter was
increased in all test groups but not in a dose-related manner. Slight
diarrhoea occurred only at the 50 per cent. level in both sexes and
this was unaffected by the feeding of additional cellulose in the
diet. No loss of hair was noted (de Groot & Spanjers, 1970).
The feeding studies with rats did not show any deleterious effects.
The available evidence for the group of modified starches considered
suggests that caecal enlargement without associated histopathological
changes is of little toxicological significance. Several short-term
studies, a two-year study and a reproduction study in rats are now
available for evaluation.
Temporarily not limited.*
Further work required by 1973
Histological report to complete the two-year rat study.
Histological report to complete the reproduction study.
de Groot, A. P. & Spanjers, M. Th. (1970) Report No. R 3096 by
Centraal Instituut voor Voedingsonderzoek
Feron, V. J., Til, H. P. & de Groot, A. P. (1961) Report No. R 2329 by
Centraal Instituut voor Voedingsonderzoek
* Except for good manufacturing practice.
Kruger, L. (1970) Unpublished reports Nos 405 & 406 submitted by
National Starch and Chemical Corp.
Leegwater, D. C. (1971) Unpublished report No. R 3431 by Centraal
Instituut voor Voedingsonderzoek
Oser, M. (1961) Unpublished report No. 79868 b and c by Food and Drug
Research Laboratories Inc., submitted by National Starch and Chemical
Pieters, J. J. L., van Staveren, W. A. & Brinkhuis, B. G. A. M. (1971)
Unpublished report No. R 3433 by Centraal Instituut voor
Til, H. P., Spanjers, M. Th., van der Meulen, H. C. & de Groot, A. P.
(1971a) Report No. R 3363 by Centraal Instituut voor Voedingsonderzoek
Til, H. P., Spanjers, M. Th., & de Groot, A. P. (1971b) Report No. R
3403 of Centraal Instituut voor Voedingsonderzoek
Turner, A. W. (1961) Unpublished report of Avebe. Submitted by Assoc.
Amidonneries de Mais