Protective Effect of Milk on Mineral Precipitation by Na Phytate

Abstract

Sodium phytate was added to milk with and without the addition of Fe or Zn and the solubility of the endogenous Ca and added Fe or Zn was not affected. However, when these experiments were repeated with a model system containing CaC12 at the same calcium concentration as milk, the addition of Na phytate caused a significant precipitation of each of these minerals. These results suggest that milk exerts a protective effect on the phytate induced precipitation of these minerals and thus their potential bioavailability.

Mineral absorption by albino rats as affected by some types of dietary pectins with different degrees of esterification

“…The magnitude of effect of each two previous factors can not be clearly isolated. Hence, it may be concluded that the mechanism of impairing the absorption of monovalent minerals has mainly proceeded through physical action i. e. the elastic gels fo the highly esterified pectins favoured hosting the small monovalent ions between the loosely crosslinked pectin chains in accordance with the previous observations of Platt and Clydesdale [23]. During the movement of digested food from the acidic condition in the stomach to the intestine, the pH may lay within the range optimal for gel formation.…”

“…In conclusion, it is remarked in the most cases that the degree of esterification and not the amount of free carboxyl groups is more determinant of the mineral binding in accordance with Platt and Clydesdale [23]. Hence, pectins may be useful in counteracting heavy metals poisoning.…”

“…The amount of free carboxyl groups does not only determine the biochemical action of pectin through the side reaction with other functional groups but also may affect the physical properties of pectin [23], which by its turn influence the physical interactions with other food constituents. It was found that pectin with high degree of esterification forms elastic gels with only moderate crosslinking between pectin chains and will allow water and solutes to distribute interstitially, while pectins with low degree of esterification form rigid gels and may exclude the mobility of solutes [23].…”

“…It was found that pectin with high degree of esterification forms elastic gels with only moderate crosslinking between pectin chains and will allow water and solutes to distribute interstitially, while pectins with low degree of esterification form rigid gels and may exclude the mobility of solutes [23]. Hence both the physical structure of pectin and the reactivity of the free carboxyl groups will exert their respective actions on mineral absorption either through physical or chemical mechanism.…”

“…This controversy may be due to the different level and different type of pectin used in every study. However, food pectins differ in their physical structure [21,22] and the degree of esterification which determine their capability of binding minerals [23]. On the other hand, a marked decrease in heavy metals in the blood have been observed after the administration of pectin solutions and consequently pectin is regularly provided to people working under conditions liable to cause poisoning with harmful metals [24].…”