The effect of iodine fortification on – the antioxidant activity of carrots and cauliflower

Introduction. In many countries worldwide, food fortification programs with iodine are carried out to mini­mise the risk of a deficiency of this element in the diet. However, preliminary studies have shown correlations between antioxidant activity and iodine content.
Aim. The aim of this study was to examine the use of cauliflower and carrots as matrices for potassium iodide (KI) and potassium iodate (KIO3) at different concentrations. It was hypothesised that iodine compounds and their concentrations affect the antioxidant activity of fortified cauliflower and carrots.
Material and methods. The study tested variable iodine concentrations: 0.023; 0.23; 0.77; 1.30; 2.30 and 3.0 mg KIO3 or KI/100 g. These iodine concentrations were applied to two varieties of carrot and two varie­ties of cauliflower. After the fortification process and 60, 120, 180, 240, and 320 days of storage, the iodine content was determined. Additionally, after 320 days of storage, the antioxidant activity of all vegetable sam­ples was analysed (based on two free radicals scavenging indices, the DPPH scavenging capacity (DPPH•) and the ABTS scavenging capability (ABTS•+)).
Results. Covariance between the iodine compound (KI/KIO3) and the ABTS•+ and DPPH• test results of forti­fied carrots and cauliflower was noted. For the samples of dried carrots and cauliflower with iodine concen­trations from 0.23 to 3.0 mg kg−1 of KI or 0.23 to 1.30 mg kg−1 of KIO3, the free-radical scavenging capacity indices were similar to those for samples not fortified with iodine. However, for the samples of both carrots and cauliflower with KIO3 at 2.30 to 3.0 mg kg−1, the capacity to terminate ABTS•+ and DPPH• was lower than in samples without iodine. This was especially true after storage.
Conclusions. Cauliflower and carrots can be good iodine matrices. However, to maximise free radical scav­enging indices, iodine should be fortified at concentrations of up to 2.30 mg kg−1.