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    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)