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


    DISTARCH GLYCEROL

    Treatment with epichlorhydrin under akaline conditions up to 0.3 per
    cent. tends to produce cross-linking at a rate of one glycerol diether
    linkage per 220 - glycopyranose units.

    Biological data

    Biochemical aspects

    Much evidence in the literature points to etherified starches being
    somewhat resistant to enzymic degradation.  Probably small fragments
    containing the ether linkage will remain and will not be absorbed
    readily.  Any material absorbed is likely to be excreted by the
    kidney. No direct experimental evidence exists for this particular
    hypothesis (French, 1960).  The metabolic fate of methylglucose is
    cited as collateral evidence.  Although methylglucose is absorbed by
    rats (Sols, 1956) no demethylation is believed to occur (Csaky &
    Wilson, 1956) and excretion is essentially quantitative (Csaky &
    Glenn, 1957). The in vitro digestibility by amyloglucosidase of
    distarch glycerol (0.3 per cent. epichlorhydrin) was shown to be 98.3
    per cent. of that of unmodified starch (Kruger, 1970). The caloric
    values of two starches treated at levels of 0.07 per cent. and 0.50
    per cent. epichlorhydrin were estimated in groups of 10 weanling male
    rats by comparing the weight gain obtained after feeding for 28 days a
    basal diet supplemented with 3 g of each starch against a
    dose-response curve obtained by feeding daily sucrose supplements of
    0, 1.5 g, 3 g, 4.5 g and 6 g equivalent to approximately 0, 6, 12, 18
    and 24 calories.  Distarch glycerols were only slightly lower in
    caloric value than unmodified starch, the differences not being
    significant.

    Short-term studies

    Rat

    Three groups of 10 male and 10 female rats were fed for 90 days
    unmodified starch or starch treated with 0.07 per cent. or 0.50 per
    cent. epichlorhydrin at 71 per cent. of their diet. Growth rate,
    appearance, behaviour and food intake were similar in all 3 groups.
    Haematological investigations showed no abnormalities related to the
    feeding of modified starches.  Non-protein nitrogen blood levels and
    blood sugar levels remained normal in all groups.  The weights of all
    major organs were normal and no abnormal gross or histopathological
    changes related to treatment were seen.

    Long-term studies

    None available.

    Comments

    The feeding studies with rats show that the modified starch is well
    utilized.  The available evidence for the group of modified starches
    considered suggests that caecal enlargement without associated
    histopathological changes is of little toxicological significance. 
    The short-term rat study shows no adverse effects at the high dietary
    level used.  No long-term study on this modified starch is available
    and collateral evidence from the long-term and reproduction studies
    with hydroxypropyl distarch glycerol, a more highly modified starch,
    indicates that the glycerol linkage is causing no adverse effects.

    EVALUATION

    Temporarily not limited.*

    Further work required by 1973

    Histological report to complete the 2-year rat study on hydroxypropyl
    distarch glycerol.

    Histological report to complete the reproduction study on
    hydroxypropyl distarch glycerol.

    REFERENCES

    Csáky, T. Z. & Wilson, J. E. (1956a) Biochem. Biophys. Acta., 22, 185

    Csáky, T. Z. & Glenn, J. E. (1956b) Amer. J. Physiol., 188, 159

    French, D. (1960) Unpublished report

    Kruger, L. (1970) Unpublished reports Nos 405 & 406 submitted by
    National Starch and Chemical Co.

    Oser, B. L. (1961) Unpublished report of Food and Drug Research
    Laboratories Inc., submitted by National Starch and Chemical Corp.

    Sols, A. (1956) Rev. esp. Fisiol., 12, 17


                   

    * Except for good manufacturing practice.
    

    See Also:
       Toxicological Abbreviations
       Distarch glycerol  (FAO Nutrition Meetings Report Series 46a)
       Distarch glycerol (WHO Food Additives Series 5)
       DISTARCH GLYCEROL (JECFA Evaluation)