FAO Nutrition Meetings Report Series 
    No. 46A WHO/FOOD ADD/70.36

    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
    27 May - 4 June 19691

    Food and Agriculture Organization of the United Nations

    World Health Organization

    1 Thirteenth report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, in press;
    Wld Hlth Org. techn.  Rep. Ser., in press.


    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. Some depolymerization
    takes place by rupture of the bonds between glucose units. No chlorine
    in introduced into the molecule and the final products usually contain
    only residues of sodium chloride, sodium sulfate and sulfur dioxide.

    Oxidation with hypochlorite

    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 lightly 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 pancreatic than unmodified starch but there was no obvious
    difference as regards salivary digestion (Shuman, A. 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 at al., 1951).

    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, 1963).

    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 6.4
    (?) per cent. (5.23 COOH per IOD 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 all dietary levels. One rat from each of
    the high dietary level groups Showed marked caecal dilation only in
    animals fed the heavily oxidized starch (Whistler & Belfort, 1961).

    Acute toxicity

    None supplied

    Short-term studies

    Rat. 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.


    Hypochlorite-oxidized starch has been investigated by digestibility
    studies in vitro and in vivo. One Short-term study over 10 weeks
    was reported only in outline and referred to one particular commercial
    sample. Assimilation difficulties and delayed in vitro enzymic
    degradation occur only at high levels of oxidation together with
    diarrhoea and caecal dilatation. Hypochlorite oxidation affects the
    physical properties of the starch; provided the chemical change is
    limited to the introduction of no more than 1 carboxyl group per 28
    anhydroglucose units and a carbonyl content which is negligible, the
    biological effects of the modified starch do not appear to be
    deleterious. Despite the paucity of animal data and lack of any
    information in man it would be unwarranted to exclude the use of
    oxidized starches (containing no more than 1 carboxyl group per 28
    anhydroglucose units) as food additive pending the provision of
    metabolic studies preferably in man.


    Temporarily not limited except for good manufacturing practice.

    Further work required by June 1972

    Metabolic studies in several species.


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

    Garton Sons & Co. Ltd., (1967) Submission to U.K. authorities

    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 (WHO Food Additives Series 1)
       Oxidized starches (WHO Food Additives Series 5)
       Oxidized starches (WHO Food Additives Series 6)