Effects of food processing and fruit juices on in‐vitro estimated iron availability from cereals, vegetables and fruits

Selected processed foods were digested in vitro under simulated physiological conditions. The proportion of iron diffusing across a semi‐permeable membrane was used as an index of bioavailability. Certain food processing procedures appeared to greatly enhance the proportion of diffusible iron. Many of the foods that were canned, dried, pickled, fermented, refined, or which contained certain additives, displayed enhanced iron diffusibility compared with unprocessed foods. Iron diffusibility from wheat flour was found to be enhanced by the addition of fruit juices. The constituent organic acids in the fruit juices, namely citric, ascorbic and malic, were found to be potentially responsible for this enhancement. These three compounds are also important examples of a sequestrant, an antioxidant, and an acidulant. These and similar compounds are added to many processed foods in order to improve their quality and preservation. All such additives have the potential to influence the chemical form, and probably the bioavailability, of food iron.