Phytic acid flour

Overall, the large number of significant differences among the fractions of all three bean types, reveals that the various minerals studied were not equally distributed among the fractions, except for sodium, but rather that partitioning occurred. Consistent with the ash values obtained, the protein flour fractions of the three bean types contained larger amounts of Fe, Mg, P, Z, and K whereas the starch II fractions contained smaller amounts of these minerals and Ca and Cu than the other flour fractions. Phytic acid content ranged from 8.7-30.2 mg/g for navy flours, from 4.3-23.7 mg/g for pinto flours. Total phosphorus content correlated well with both phytic acid content and protein content. Phytic acid content was... 

Ravindran (1991) estimated the protein content of ragi to be 9.8%, that of calcium, oxalate, and phytic acid to be 0.24%, 0.44 mg%, and 0.48%, respectively. Hadimani and Malleshi (1993) compared the protein, lipid, ash, calcium, phosphorus, and dietary fiber contents of seven native and milled millets. The protein content of ragi milled flour decreased by 61%... 

When adding animal protein in the form of milk, egg and cheese to the whole flour meal, the zinc absorption was increased. (Table II). It seems like the binding of zinc to phytic acid and fibercomponents is overcome if enough animal protein is served together with the whole flour bread. 

In animal experiments it has been shown that a high calcium content in combination with the phytic acid in whole flour bread will decrease the zinc absorption (10), When adding milk and milk products to the whole flour bread in Dr. Sandstr0ms experiments the same positive effect was seen from the protein despite of the higher calcium content (Table III). 

It is possible that the protein competes with the binding to phytic acid or fiber comnonents in whole flour bread rather than facilitating zinc absorption. 

By increasing the fermentation period when making the dough for the bread, the decreased zinc absorption in whole flour bread can be overcome. The phytic acid is in this way broken down, and the zinc better available absorption. 

An increase in consumption of whole grain flour products is the nutritional aim in Norway. The high content of dietary fiber or factors associated with it, however, present in bran and whole grain flour, may interfere with the bioavailability of iron as indicated by several authors (2,3,4). Phosphate and especially phytic acid present in unrefined cereal products have frequently been said to be potent inhibitors of iron absorption (5,6). 

Phytic Acid. Recent reviews (67,68,69) summarized the literature covering the relationship between phytic acid and mineral bioavailability in soy protein products. The formation of phytate-proteln-mineral complexes (particularly zinc chelates in flours, concentrates, and Isolates prepared from mature soybeans) may be responsible for reduced mineral availability. However, the iron in Fe-labeled mature soybeans is more available to iron-deficient rats than the iron in green-immature soybeans, even though mature soybeans contain three times more phytic acid (70). The factor(s) responsible for this difference in bioavallablllty has not been identified. 

The addition of phytic acid to white flour markedly reduced the absorption of these minerals in short-term studies. With prolonged ingestion, the body can adapt to a high phytate intake apparently as a result of the action of enzymes which release the phosphate from soluble phytates. Phytases may be derived from the food, the digestive secretions or the intestinal bacteria. 

Controversy has been raging for many years as to whether, from the nutritional point of view, white or brown bread is better. Brown bread made from high extraction flour contains more protein, calcium, iron, B vitamins and fibre than white bread but its nutrients tend to be less well digested and absorbed. The case for white bread is based on its more attractive appearance, finer texture, better baking and keeping qualities and also its lower content of fibre and phytic acid which are responsible for the poorer utilization of nutrients. In Britain, where bread is only one of many articles of diet, nutritional differences between wholemeal and fortified white flours are of little practical significance. However, such differences could become important if bread ever became the single staple food. 

Should the Government ensure that the flour should be as nutritious as possible For instance, should ascorbic acid and zinc be added as well as a variety of other nutrients Bread has been used as a vehicle for nutrients not removed from it iodised salt in goitrous areas of the Netherlands since 1943 and Australia since 1953 sodium chloride to combat prostration in the Armed Forces from sweating in very hot conditions calcium, partly to offset the phytic acid in flours of higher extraction and partly as a supplement. There is no objection to these practices anyone who objects to, for instance, the calcium can use wholemeal flour to which no nutrients are artificially added. But to strive to make flour as nutritious as possible would be unreasonable. 

Many iron-fortified products have been tested for the compatibility of the fortificant with the food vehicle and for the bioavailability of the fortified iron, but few efficacy or effectiveness trials have been done. Iron-fortified fish sauce, sugar, infant formula, and infant cereal have been shown to improve iron status. In contrast, attempts to fortify cereal flours with iron have met with little success because they contain high levels of phytic acid and the characteristics of these foods require the use of poorly bioavailable iron compounds. 

Several dietary constituents decrease the bioavailability of calcium in food. Increasing fiber intake by, for example, replacing white flour by whole wheat flour in a typical Western diet has long been associated with negative calcium balance even when calcium intakes meet recommended levels. Likewise, the fiber in fruits and vegetables can cause negative calcium balance. In cereals, phytic acid is the main constituent of fiber that binds calcium, making it unavailable for absorption. The... 

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