FAO Nutrition Meetings
Report Series No. 40A,B,C
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
Synonym Stearyl palmityl tartrate
Chemical description Di-stearyl/palmityl tartrate
Empirical formula C40H78O6 to C38H74O6
Structural formula HO-CH-COOR
Where R = (CH2)17-CH3 or up to 50 per
Molecular weight 654 to 626
Definition The material shall be the product of the
esterification of tartaric acid with
commercial stearyl alcohol, which
consists essentially of stearyl and
It shall consist mainly of di-ester,
with minor amounts of mono-ester and of
unchanged starting materials, the total
ester content being not less than 90 per
cent. by weight.
Description Stearyl tartrate occurs as a
cream-coloured unctuous substance.
Use As a dough strengthening agent.
Stearyl tartrate is made from stearyl alcohol and tartaric acid.
The only impurities present in any significant amount are unreacted
stearyl alcohol and tartaric acid. Both of these substances occur
naturally in the diet and they have no toxicological significance at
the level of use of stearyl tartrate. Commercial stearyl alcohol
contains 50 per cent. cetyl alcohol which is handled similarly to
stearyl alcohol in the body. The use of deuterium-labelled cetyl and
stearyl alcohol has shown that they are largely converted into the
corresponding palmitic and stearic acids which mix with fatty acid
pool and enter normal metabolism. The actual proportion of cetyl and
stearyl alcohol is not expected to make any difference in their
biological effect (Den Stetten & Schoenheimer, 1940; Schoenheimer &
Hilgetag, 1934). The ester linkage between the primary alcohol and
tartaric acid is split by liver esterases but not by pancreatic
lipase. 14C-labelled stearyl tartrate was poorly absorbed in rats
when fed as a suspension in water, or mixed with food; about 90 per
cent. or more was recovered from the stools. When labelled stearyl
tartrate was administered as a 1 per cent. solution in olive oil,
50-80 per cent. was absorbed in 7 out of 10 rats; the other 3 rats
showed poor absorption. Study of the metabolism of labelled stearyl
tartrate, administered as an oily solution was carried out in rats
using a closed system for the recovery of 14CO2. It was shown that
carbon dioxide was released from stearyl tartrate at a rate equivalent
to the elimination of 13.5 mg of stearyl tartrate/kg body-weight/24 h.
Continued administration of stearyl tartrate over a period of 10 days
did not cause any reduction in its rate of metabolism. There was no
preferential accumulation of labelled stearyl tartrate in any organs
or in adipose tissue over the period of these experiments. The rate of
elimination demonstrated exceeded the rate of absorption, so that
cumulation would not be expected to occur (Frazer et al., 1954a;
The absorption of olive oil containing 1 per cent. of stearyl
tartrate over a period of 3 hours in the rat was compared with the
absorption of olive oil alone in groups of 10 rats. The average
absorption in the two groups was 83 per cent. and 86 per cent.
respectively after administration of 1.0 ml of oil intragastrically.
The gross and microscopic appearances of the small intestine were
normal in all animals (Frazer et al., 1954b).
Single doses of up to 5000 mg/kg orally and up to 2000 mg/kg.i.m.
of stearyl tartrate in aqueous or oily vehicle were administered to
groups of mice, rats, guinea-pigs, rabbits and dogs. Over the dosage
range studied, no abnormalities were detected that could be attributed
to the administration of stearyl tartrate (Frazer et al., 1954b).
Rat. Groups of 50 male weanling rats were fed diets containing
0, 2.5 and 5 per cent. of stearyl tartrate. Appearance, behaviour and
rate of weight gain in the three groups showed no significant
difference during the rapid growth period. At 15 months no significant
differences were found in hepatic and renal function between control
and treated groups. Gross and histopathological examinations of the
main organs on autopsy revealed no abnormalities attributable to
stearyl tartrate (Ahmad, 1953; Frazer et al., 1954b).
Man. Bread was fed to 15 human volunteers for a period of 4
years. Ten received bread containing 0.075 per cent. of stearyl
tartrate and 5 received untreated bread. No difference was observed
between the groups with regard to general health, appetite,
body-weight, haemoglobin, blood counts and urinary constituents
(Frazer et al., 1954b).
Mouse. Four groups of male and female mice were fed diets
containing either 57 per cent. of untreated bread, or 57 per cent. of
bread treated with 3.2 per cent. of stearyl tartrate, or diets
containing 3.2 per cent. of glyceryl monostearate or 3.2 per cent. of
stearyl tartrate plus 3.2 per cent. of glyceryl monostearate. Nine
generations of mice were studied. At the start of the experiment one
of the stearyl tartrate groups developed an infection and the group
had to be restocked; however a further 9 generations were produced on
this diet without any difficulties. No significant difference was
observed between the groups, in regard to reproduction, lactation,
weight gain of the young, general health, appearance and survival
(Frazer et al., 1954b).
Rat. Four groups of 10 male and 10 female rats were fed diets
containing 57 per cent. of bread either untreated or treated with 3.2
per cent. of stearyl tartrate, 3.2 per cent. of glyceryl monostearate
or 3.2 per cent. of stearyl tartrate plus 3.2 per cent. of glyceryl
monostearate. These diets were fed for the life span. The appearance,
behaviour, rate of weight gain, and general health of these animals
was kept under close observation. At the end of the period the
survivors were killed and autopsied. The main organs were examined
microscopically. There were no apparent differences in tumour
incidence, nor other pathological changes (Frazer et al., 1954b).
Four groups of male and female rats were fed the diets described
above. Four generations of rats were studied. No significant
difference was observed between the different groups in regard to
reproduction, lactation, rate of weight gain of young, general
appearance and survival (Frazer et al., 1954b).
Groups of 10 male and 40 female rats were fed a control diet and
diets containing bread treated with 1 or 5 per cent. stearyl tartrate.
The second and third generations of animals on these diets were
followed for their life span. At 36 weeks, there was no significant
difference in body-weight gain. Hepatic function, reproduction and
lactation, and morbidity or mortality showed no significant difference
between the three groups. When killed at the end of two years no
statistically significant difference was found between the control and
the test groups with regard to pathological findings or tumour
incidence (Frazer et al., 1954 b).
Stearyl tartrate has been extensively studied in animals.
Metabolic studies in the rat revealed that it is poorly absorbed under
ordinary circumstance, but that if it is absorbed it can be
metabolized and does not accumulate in the tissues. There exists
little doubt concerning the safety and freedom from carcinogenic
hazard of stearyl tartrate.
Acceptable level of treatment
Bread: 0-500 mg/kg flour.
Ahmad, N. U. (1953) Toxicological studies of fatty acid esters and
related compounds, Ph.D. thesis, University of Birmingham, summary
submitted to WHO
Frazer, A. C. (1955) Voeding 16, 535
Frazer, A. C., Pover, W. F. R. & Simmons, H. G. (1954a) Proc. Second
Radio-isotope Conference, I, 298, Butterworth, London
Frazer, A. C., Ahmad, N. U., Hickman, J. R., Sharratt, M., Pover, W.
W. F. R. & Sammons, H. G. (1954b) Unpublished report submitted to WHO