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    FAO Nutrition Meetings
    Report Series No. 40A,B,C
    WHO/Food Add./67.29




    TOXICOLOGICAL EVALUATION OF SOME
    ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS,
    STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES





    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
    13-20 December, 19651 Geneva, 11-18 October, 19662




                   

    1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; 
    Wld Hlth Org. techn. Rep. Ser., 1966, 339

    2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1967, in press; 


    Food and Agriculture Organization of the United Nations
    World Health Organization
    1967


    PROPYLENE GLYCOL ESTERS OF FATTY ACIDS

    Chemical description         Mixtures of propylene glycol mono- and
                                 di-esters of fatty acids of food fats.

    Structural formula

                                 CH3-CH-OR
                                     '
                                     CH2-OR

                                 Where R or R' represents the fatty acid
                                 moiety and R or R' is hydrogen in the
                                 mono-esters.

    Definition                   Propylene glycol esters of fatty acids
                                 are mixtures of the esters of these
                                 fatty acids with propylene glycol.
                                 They are mainly the mono-esters with
                                 some di-esters and the commercial
                                 products will contain mono- and
                                 diglycerides when fats are used for
                                 transesterification with propylene
                                 glycol.

    Description                  Propylene glycol esters are white to
                                 yellowish white beads, or flakes having
                                 a bland odour and taste.

    Uses                         As emulsifier.
                                 The content of propylene glycol in the
                                 commercial products must be indicated on
                                 the label.

    Biological Data

    Biochemical aspects

         Pancreatic lipase hydrolysed 70 per cent. of propylene glycol
    monostearate in vitro at 40 in 15 hours (Balls & Matlack, 1938).
    Similarly, steapsin hydrolysed 70 per cent. of propylene glycol
    distearate (PGDS) in vitro at 30 in 18 hours (Long et al., 1958).
    The absorption, metabolism and hydrolysis of PGDS was studied in rats
    using isotopically labelled compounds, and found to be similar to
    those of the glyceryl stearate esters (Long at al., 1958a; 1958b).

    Acute toxicity

         No data are available.

    Short-term studies

         Rat. Six 21-day old rats were fed for 40 days a diet containing
    60 per cent. propylene glycol ester. The animals showed no adverse
    effect on body-weight gain. On histological examination of the kidneys
    no lesions were observed (Lepkovsky et al., 1935).

    Long-term studies

         No data are available.

    Comments

         There is evidence that the propylene glycol esters of fatty acids
    are hydrolyzed to propylene and fatty acids. Evaluation is based
    on the content of propylene glycol, for which an acceptable daily
    intake has been established (FAO/WHO, 1964).

    Evaluation

    Estimate of acceptable daily intakes for man

                                       mg/kg body-weight1

       Unconditional acceptance             0-20
       Conditional acceptance               20-60

    REFERENCES

    Balls, A. J. & Matlack, M. B. (1938) Biochem. J., 123, 679

    FAO/WHO (1964) FAO Nutrition Meetings Report Series No. 35; 
    Wld Hlth Org. tech. Rep. Ser ., 281

    Lepkovsky, S., Ouer, R.A. & Evans, H.M. (1935) Biochem. J., 108,
    431

    Long, C. L., Zeitlin, B. R. & Thiesen, R. jr (1958a) Arch.
    Biochem.,77, 440

    Long, C. L., Domingues, F.J., Studer, V., Lowry, J. R., Zeitlin, B.R.,
    Baldwin, R. R. & Thiesen, R. jr (1958b) Arch. Biochem., 77, 428

                   

    1 Calculated as propylene glycol; see the Seventh Report of the Joint
    FAO/WHO Expert Committee on Food Additives (FAO/WHO, 1964).
    


    See Also:
       Toxicological Abbreviations
       Propylene glycol esters of fatty acids (WHO Food Additives Series 5)
       PROPYLENE GLYCOL ESTERS OF FATTY ACIDS (JECFA Evaluation)