Addition of different iron salts to flour : The factor of rancidity

Flour is enriched with vitamin B1, nicotinic acid and iron by adding a master‐mix which, in addition to flour and the two vitamins, normally contains reduced iron (ferrum redactum). Master‐mixes containing different iron salts have been examined for their oxidative stability and it has been found that the length of the induction period of the master‐mix in oxygen at 100° and the time for it to develop a rancid taint when stored at room temperature vary with the salt used. The length of the induction period of a master‐mix is a useful guide to its effect on the oxidative stability of a flour to which it has been added. Enriched flours which developed rancidity taints were those containing master‐mixes with short induction periods. Other factors including chemical treatment are shown to affect the oxidative stability of a flour. In addition, vitamin B1 has been found to have pro‐oxidant and nicotinic acid to have antioxidant activity.