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    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)