WHO Food Additives Series 1972, No. 1


    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




    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


    Biological data

    Whatever oxidizing agent is used only minor modifications of the
    starch molecule are achieved in normal manufacturing practice.  These
    are equivalent to the introduction of 1 per cent. w/w of carboxyl
    (-COOH) or 0.5 per cent. w/w of keto (-CO) groups or, 3.6 carboxyl and
    2.9 carbonyl groups per 100 glucopyranose units.  No chlorine is
    introduced into the molecule and the final products usually contain
    only residues of sodium chloride, sodium sulfate and sulfur dioxide.

    Biochemical aspects

    Early comparative experiments pointed to inhibition of amylolysis
    (Tremolières et al., 1959).   In vitro digestibility by pancreatin
    or saliva was used to compare slightly and highly oxidized corn starch
    with unmodified corn starch and a reference starch.  Maltose
    production after a fixed interval of enzyme action was taken as a
    measure of digestibility.  The oxidized starch was 10-15 per cent.
    less digestible by pancreatin than unmodified starch but there was no
    obvious difference as regards salivary digestion (Shuman, C. C. &
    Mertz, E. T., 1959).  The digestibility of oxidized wheat starch
    (conditions not stated) was examined in rats by matched-feeding
    techniques using the modified starch as the sole source of
    carbohydrate at a level of 63.7 per cent. (dry basis) of the diet. 
    The degree of assimilation by and the general effects on groups of 6
    rats over a feeding period of 28 days were assessed from consideration
    of body-weight changes, faecal residues, digestibility coefficients
    for starch and post-mortem appearance of the animals and their
    gastrointestinal tracts.  The digestibility coefficients were
    calculated from the starch content of ingested food and residues found
    in faeces and post-mortem gastrointestinal contents.  Body-weight gain
    and digestibility coefficients were practically indistinguishable from
    those obtained for wheat starch or corn starch.  Nothing abnormal was
    noted on post-mortem examination (Booher et al., 1959).

    Other studies, in 3 groups of 3 rats each, used corn starch oxidized
    with 3.9 per cent., 4.5 per cent., or 5.5 per cent., hypochlorite
    calculated as chlorine.  This corresponds to the introduction of 0.57
    per cent., (2.04 COOH groups per 100 glucopyranose units), 0.8 per
    cent., (2.86 COOH groups per 100 glucopyranose units) and 0.9 per
    cent. (3.57 COOH groups per 100 glucopyranose units) carboxyl groups.
    To 5 g basal diet were added 1, 2 or 4 g modified or control starch
    and this diet was fed to rats for 10 days.  Comparison of
    digestibilities showed an apparent decrease with increasing oxidation
    but no effect on caloric values.  No tissue damage was associated with
    the diarrhoea and caecal enlargements observed in groups receiving 2 g
    or 4 g starch in their feed.  Liver, kidney, heart and spleen weights
    were normal.  Diarrhoea and caecal enlargement are known to occur in
    rats fed starches of poor digestibility or other carbohydrates (White,

    The digestibility of oxidized starches at levels of 2.5 per cent., 6
    per cent. and 43.2 per cent. calculated as chlorine, equivalent to a
    carboxyl content of 0.32 per cent. (1.15 COOH per 100 glucopyranose
    units), 0.9 per cent, (3.81 COOH per 100 glucopyranose units) or 1.46
    per cent. (5.23 COOH per 100 glucopyranose units), was studied in
    groups of 6 male and 6 female rats.  The animals were kept for 7 days
    on 5 g basal diet and then given either 1 g or 2 g starch supplements
    for 21 days.  Poor weight gain with diarrhoea were noted only with the
    highly oxidized material at both dietary levels.  One rat from each of
    the high dietary level groups was examined.  Marked caecal dilatation
    was seen only in animals fed the heavily oxidized starch.  It is to be
    noted that this very highly oxidized starch is a commercially
    unacceptable product (Whistler & Belfort, 1961).

    Short-term studies


    Starch treated at a level of 0.375 per cent. chlorine was fed to
    weanling albino rats at 70 per cent. of their diet for 10 weeks with
    corn starch as control.  Feeding was either unrestricted or by
    paired-feeding technique.  No toxic effects were noted.  No details of
    this work, carried out in 1944-5, were available (Garton Sons & Co.
    Ltd., 1967).

    Long-term studies

    None supplied.


    The digestibility of hypochlorite-oxidized starch has been
    investigated  in vivo and found to be similar to that of unmodified
    starch.  The longest of the short-term studies reported extended only
    over 10 weeks and was carried out with an inadequately defined sample.
    Studies with highly oxidized starches (1.4 per cent. or more carboxyl
    groups) are not applicable because these products are not commercially
    acceptable.  Provided the chemical change is limited to the
    introduction of no more than 1 carboxyl group per 25 anhydro-glucose
    units, the biological effects of the modified starch do not appear to
    be deleterious.


    Temporarily not limited.*

    Further work required by 1973

    Ninety-day studies in 2 species.


    * Except for good manufacturing practice.


    Booher, L. E., Behan, I., & McMeans, E. (1951) J. Nutr., 45, 75

    Garton Sons & Co. Ltd. (1967) Unpublished report

    Shuman, A. C. & Mertz, E. T. (1959) Unpublished report No. 4 of Shuman
    Chemical Lab. Inc. to Corn Industries Research Foundation

    Tremolières, J., Bernier, J. J. and Lowy, R. (1959) Nutritio et Dieta,
    1, 100

    Whistler, R. L., and Belfort, A. M. (1961) Science, 133, 1599

    White, T. A. (1963) Cereal Science Today, 8, 48


    See Also:
       Toxicological Abbreviations
       Oxidized starches  (FAO Nutrition Meetings Report Series 46a)
       Oxidized starches (WHO Food Additives Series 5)
       Oxidized starches (WHO Food Additives Series 6)