FAO Nutrition Meetings
Report Series No. 40A,B,C
WHO/Food Add./67.29
TOXICOLOGICAL EVALUATION OF SOME
ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS,
STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES
The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
13-20 December, 19651 Geneva, 11-18 October, 19662
1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, 1966 No. 40;
Wld Hlth Org. techn. Rep. Ser., 1966, 339
2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, 1967, in press;
Food and Agriculture Organization of the United Nations
World Health Organization
1967
ACETIC ACID AND FATTY ACID ESTERS OF GLYCEROL
Synonyms Acetylated mono-and diglycerides; Acetic
acid esters of mono-and diglycerides;
Acetoglycerides; Acetofats
Chemical description The product consists of mixed glycerol
esters of acetic acid and fatty acids.
Structural formula
CH2 - OR
CH - OR'
CH2 - OR"
Where R, R' and R" represents the fatty
acid or acetic moiety and R or R' will
be hydrogen in the case of the mono- or
di-esters.
Definition Acetylated mono- and diglycerides
contain mono- and some di-esters of
fatty acids with glycerol which is
itself partially acetylated. The product
may contain free glycerol and free fatty
acids.
Description Acetylated monoglycerides vary in
consistency from liquids to solids and
are white to pale yellow in colour. They
may have an acetic acid odour.
Uses As emulsifier.
Biological Data
Biochemical aspects
The long-chain fatty acids in triglycerides may be replaced with
one or more acetic acid groups to produce mono- or diacetins
(acetoglycerides) which are resistant to changes in consistency, heat
damage and oxidative rancidity (Alfin-Slater et al., 1958; Ambrose &
Robbins, 1956b). Lipolytic studies in rats showed the presence of
large amounts of free fatty acids but only traces of free acetic acid
in the lipids isolated from the stomach after feeding acetoglycerides.
Ligation of the pylorus indicated a more rapid absorption or the
acetic acid moiety by the stomach wall than of glycerol and monoacetin
(Hertnig et al., 1956). Absorption of acetoolein or acetostearin,
given as 20 per cent. of the diet, was studied in groups of 10 adult
male rats. Acetooleins were better absorbed than acetostearins. Faecal
lipid estimations showed much greater absorption (i.e. lowest
excretion) in rats of unsaturated acetoglycerides (acetooleins) than
of saturated acetoglycerides (acetostearins) (Ambrose & Robbins,
1956b).
The digestibility coefficients of acetoglycerides fed as 20 per
cent. of the diet to rats varied between 94 and 99 per cent. depending
on the composition of the mixture administered (Ambrose & Robbins,
1956b). In another study, groups of 10 male weanling rats were fed
diets containing 0 or 30 per cent. of 2 different acetostearins for 20
weeks. Tissue cholesterol levels (plasma, liver, adrenal) for the 30
per cent. level were similar to those in rats on a fat-free calorie
restricted diet (Coleman et al., 1963).
Acute toxicity
Animal Route LD50 Reference
(mg/kg
body-weight)
Rat oral 4 000 Ambrose & Robbins, 1956a
No toxic symptoms were seen in rats after single doses of 4000
mg/kg body-weight of acetostearin or acetoolein. Daily i.v. injection
of 80-100 mg acetostearin into rabbits for 15 days caused no apparent
ill effects and viscera showed no pathological charges. Acetostearin
cleared completely from the blood plasma within 15-30 minutes (Ambrose
& Robbins, 1956a; Alfin-Slater et al., 1958),
Short-term studies
Rat. Groups of 10 male weanling rats received diets containing
25 per cent. of either stearin, olein, diacetostearin or diacetoolein,
and additional groups received 50 per cent. olein or diacetoolein for
8 weeks or 15 per cent. acetoolein for 12 weeks. There was no
difference between test and control groups with regard to body-weight
gain, food consumption or food efficiency, except for the groups
receiving stearins. Only in the groups receiving diacetostearin was
the coefficient of utilization markedly higher. Results of examination
of blood and urine were normal (Mattson et al,, 1956). Studies for 7
months on groups of 5 male and 10 female rats using 10 per cent.
acetostearin in the diet with additional supplements of Vitamin E
showed improved reproduction performance (as measured by litter
numbers and pups per litter in four successive ratings) compared with
controls or animals on acetostearin alone (Ambrose et al., 1958b).
Long-term studies
Rat. Six groups of 5 weanling male rats each were fed diets
containing O, 0.25, 0.5, 1, 2 and 4 per cent. acetostearin, and
another 4 groups of rats ware fed diets containing 0, 0.25, 0.5 and
1.0 per cent. acetoolein for 57 weeks. Body-weight gain, food intake
and mortality did not differ from those of the controls. Measurement
of relative weights of major organs revealed decreased testicular
weights at all levels of acetoolein and with the 0.25 and 0.5 per
cent. levels of acetostearin. Microscopic examination showed no
difference from controls except for testicular hypoplasia and
suppression of spermatogenesis of a variable degree in all test groups
(Ambrose & Robbins, 1956a).
In another experiment, 3 acetostearins and 2 acetooleins were fed
to groups of 10 male and 10 female rats each at 0, 5, 10 and 20 per
cent. of their diet. Parental generation animals on 20 per cent.
acetoglyceride were sacrificed after 57 weeks, 86 weeks and 101 weeks.
Mortality rate was not increased at any dose level up to 57 weeks, but
some increase occurred in all test groups compared with controls after
86 weeks. Body-weight gain was slightly depressed at the 20 per cent.
level. Examination of major organs showed consistently reduced
testicular weight at the 20 per cent. level of all three acetostearins
and at the 5 per cent. and 10 per cent. levels of two acetostearins.
Significant liver enlargement was also observed at the 20 per cent
level of acetostearins but liver glycogen was unaffected. Food
utilization was decreased by acetostearin more than by acetoolein
depending on dose. A variety of pathological changes ware observed
with individual acetoglycerides at varying dietary levels, but these
changes were attributed to imbalance of the test diet with respect to
Vitamin E and essential fatty acids. Fatty tissue changes reminiscent
of sclerema adiposum neonatorum (foci of foreign body reactions)
especially near the gut were seen with all acetostearins at 20 per
cent. level but none in the other groups (Ambrose et al., 1956a).
Comments
Acetoglycerides are readily hydrolysed in the gastrointestinal
tract and dealt with in the body in a manner similar to other
glycerides. The digestibility studies are only of limited value since
the inclusion of materials of this sort in an adequate quantity of
lipid fat, occurring naturally in the diet, ensures satisfactory
absorption. Dietary loads of a food additive in excess of 10 per cent.
are of little value in the assessment of safety-in-use as many
irrelevant effects may occur, such as observed with high-dose levels
of acetostearin. (E.g. testicular atrophy due to an increased
requirement for Vitamin E, and foreign body reaction in adipose tissue
due to overloading with saturated fatty acids.) Such effects are very
likely to be irrelevant considering the levels of use of these
compounds. Evaluation is based on the biochemical and metabolic
studies because the breakdown products are normal dietary
constituents.
Evaluation
Estimate of acceptable daily intake for man
See mixed tartaric and acetic and fatty acid esters of glycerol
(p. 96)
REFERENCES
Ambrose, A. M. & Robbins, D. J. (1956a) J. Amer. Pharm. Ass. Sci.
Ed., 45, 482
Ambrose, A. M. & Robbins, D. J. (1956b) J. Nutr., 58, 113
Ambrose, A. M., Robbins, D. J. & Cox, A. J. jr (1958a) Food Res.,
23, 536
Ambrose, A. M., Robbins, D. J. & De Eds, F. (1958b) Food Res., 23,
550
Alfin-Slater, R. B., Coleman, R. D., Feüge, R. 0. & Altschul, A. M.
(1958) J. Amer. Oil Chem. Soc., 35, 122
Coleman, R. D., Gayle, L. A. & Alfin-Slater, R. B. (1963) J. Amer.
Oil Chem. Soc., 40, 737
Hertnig, D. C., Ames, S. R., Embree, N. D. & Harris, P. L. (1956)
Fed. Proc., 15, 556
Mattson, F. H., Alexander, J. C., Baur, F. J. & Reller, H. H. (1956)
J. Nutr., 59, 277