INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY

    WORLD HEALTH ORGANIZATION



    TOXICOLOGICAL EVALUATION OF SOME
    FOOD COLOURS, EMULSIFIERS, STABILIZERS,
    ANTI-CAKING AGENTS AND CERTAIN
    OTHER SUBSTANCES



    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.


    AMYLOSE AND AMYLOPECTIN

    Biological Data

    Normal native starches consist of a mixture of 15-30 per cent. amylose
    and 70-85 per cent. amylopectin. Amylose structurally is a linear
    polymer of anhydroglucose units, of molecular weight approximately
    between 40 000 and 340 000, the chains containing 250 to 2000
    anhydroglucose units. Amylopectin is considered to be composed of
    anhydroglucose chains with many branch points; the molecular weight
    may reach as high as 80 000 000.

    One hundred per cent. amylopectin or "waxy" starches are commercially
    available having been extracted from special mutants of the parent
    plant e.g. waxy corn or waxy rice. Starches with a very high amylose
    content have also been produced, but on a limited scale for special
    application. The granules of native starches are extracted from the
    plant source by purely physical means, washed and dried. Even in this
    way a certain small amount of modification takes place so that the raw
    starch is strictly speaking not the same as it existed in the plant.
    The changes which have taken place are, however, only of academic
    interest. From the nutritional point of view it is important to
    realize that the human gastro-intestinal tract digests very
    efficiently raw cereal and root starches such as wheat, maize, rice
    and cassava but is not able to digest easily raw potato, arrowroot and
    canna starches (Booher et al., 1951).

    Digestibility of starches may be assessed by studying the action of
    pancreatin or other sources of amylase (Leach & Schoch, 1961)
    (Sandstedt et al., 1962) or of taka-diastase (Kihara & Kawase, 1949)
    in vitro on the raw granular starch, or by feeding the raw starch to
    animals such as rats and chicks. But from the standpoint of use in the
    human diet it is the gelatinized (cooked) form that requires
    evaluation. From the work of Sandstedt et al. (1962) and Borchers
    (1962) it is clear that both in vitro studies and animal feeding
    establish the resistant character of some high amylose corn starches
    to amylolytic attack.

    Nevertheless it does not appear likely that in practice high amylose
    corn starches in gelatinized form will present any problem of
    digestibility to man, who has no difficulty with gelatinized potato
    starch. The digestibility of raw granular potato starch in vitro was
    15.98 per cent. under conditions where corn starch yielded a value of
    65.64 per cent. (Kihara & Kawase, 1949). In the studies by Sandstedt
    et al. (1962) the susceptibility of potato starch in vitro to
    pancreatic digestion was far lower than that of the most resistant
    high-amylose corn starch. Although in vivo digestibility invariably
    exceeds the in vitro value, it is unlikely that potato starch would
    prove more digestible than high-amylose corn starch, either raw or
    gelatinized.

    Comments

    These native starches should be regarded as food rather than food
    additives.

    EVALUATION

    Not limited except for good manufacturing practice.

    REFERENCES

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

    Borchers, R. (1962) Cereal Chem., 39, 145

    Kihara, Y. & Kawase, Z. (1949) Rept. Food Res. Inst. (Japan), 2,
    25

    Leach, H. W. & Schoch, T. J. (1961) Cereal Chem., 38, 34

    Sandstedt, R. M. et al. (1962) Cereal Chem., 39, 123
    

    See Also:
       Toxicological Abbreviations
       Amylose and amylopectin (WHO Food Additives Series 5)
       AMYLOSE AND AMYLOPECTIN (JECFA Evaluation)