Title
In vitro availability of iron and zinc: Effects of the type, concentration and fractions of digestion products of the protein
Author
Centraal Instituut voor Voedingsonderzoek TNO
Pérez-Llamas, F.
Diepenmaat-Wolters, M.G.E.
Zamora, S.
Publication year
1996
Abstract
An in vitro dialysis method was employed to determine the effect on the Fe and Zn absorption of the type (beef, pork and soyabean) and the amount (10 and 30 g/kg) of protein present. In addition, the effects of low- and high-molecular-weight (LMW and HMW respectively) digestion products were investigated. After in vitro digestion and dialysis a lower percentage of N, Fe and Zn was found in the LMW fractions from beef, pork and soyabean proteins when the protein level was increased from 10 to 30 g/kg; the higher level of protein being associated with a lower percentage of hydrolysed protein. The highest percentage levels of intrinsic Fe were always found in the HMW fractions, independent of the type and the level of proteins studied, while in the case of Zn, both HMW and LMW fractions gave similar values. An interaction was found between inorganic Zn and non-haem-Fe. The addition of inorganic Zn (10 ug/ml) caused a significant decrease in the in vitro availability of Fe from soyabean protein, while it did not affect the dialysability of intrinsic Fe from beef and pork proteins. Our results showed that the type and the level of the protein had a positive effect on the dialysability of extrinsic Fe. We postulate that the effect of a protein on the absorption of extrinsic Fe could be accounted for by free amino acids and/or small peptides released during the digestion process and also by the undigested or partially-digested HMW fractions of hydrolysed proteins which could play a fundamental role in the availability of this essential element.
Subject
In vitro availability
Protein digestion
Protein
Protein derivative
Absorption
Bioavailability
Nutritional value
Animals
Biological Availability
Dialysis
Dietary Proteins
Digestion
Intestinal Absorption
Iron
Soybeans
Swine
Zinc
Glycine max
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TNO identifier
233534
ISSN
0007-1145
Source
British Journal of Nutrition, 76 (76), 727-741
Document type
article