Phytic acid and phytase in cereals / by Sir Edward Mellanby.

  • Mellanby, Edward, Sir, 1884-1955.
Date:
[1944?]
Catalogue details

Licence: In copyright

Credit: Phytic acid and phytase in cereals / by Sir Edward Mellanby. Source: Wellcome Collection.

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    standing of the dough snort hours) , the yeast may add largely to the phytic acid destructioA. If, however? the .> ec. st a L.-j eu is s n;all i/3.6 per cent, of flour) and the dough rising-time long (o uoursy, me yeast fhytase may be ineffective. The phyta.se action of both flour and yeast is g±6c:tl^ increased as tne pH is lowered towards 4.5? and it is possible tuat the adoitive efiect of the ls.rger amount of yeast may be partially or wholly explained by this change in t * j.’je accompanying results obtained on baking bread with flour at two levels of phytic acid content illustrate this effect of yeast. Finally, it may be asked, what are the nutritional implications of this pnytic acid—phytase problem of cereals? in tee normal hign cereal diet, three situations are presented: (l)_when_it contains much phytic acid, as when oatmeal or maize meal is largely eaten; (2) when it cont air is much inositol and phosphoric acid produced by Hydrolysis of phytic acid by ■phytase. together with some unhydrolysed phytic acid, for exampl e / when bread made from high extraction flour is eaten; (3) when it contains but little phytic acid, or hydrolysed phytic acid, as l'fen bread 1 rom low extraction flour or when a cereal such as iice is ec ten. Since both inositol, and phosphate are essential ■ ”' ^ i ‘ ~-- 1 is clearly desirable to have good supplies 01 t/.ese in the food, that is, conditions (1) and (2) above, but only so long as (a) these substances are available to the body and (b) neither phytic acid nor its product phosphor! acid is allowed to axert its calcium-stealing influence. Both these necessary conditions can be obtained by increasing the calcium in the diet and. by maintaining a sufficiently high vitamin D intake. Man, especially the Scot, instinctively found the answer to this problem in the case of oatmeal by* taking milk freely with his porridge. That is also the raison d’etre for the present practice of adding calcium carbonate to the modern loaf and vitamin D to the margarine, although It is probable that, in both cases, the present supplements are too small for the optimum calcium-phosphorus nutrition of many people. Nutrition Building, National Institute for Medical Research, (Medical Research Council), Mill Hill, N.V.7. Aug.25. (3)