A comparison of ABTS and DPPH methods for assessing the total antioxidant capacity of human milk.

INTRODUCTION The Total Antioxidant Capacity (TAC) of human milk reflects the concentration and the activity of many components which prevent oxidative degradation of fats and proteins. This study compares the effectiveness of ABTS and DPPH tests with regard to the recovery, precision and sensitivity (detection and quantification limit) of (TAC) values in human milk. MATERIAL AND METHODS TAC values were determined in twenty five samples of human milk obtained from healthy mothers, residents of Gdańsk, on the 14th day postpartum. RESULTS The average TAC of human milk determined by ABTS assay was 19.61 ±3.311 mg TE (Trolox Equivalents)/100 cm3, the average values obtained by the DPPH assay reached 9.95 ±4.36 mg TE/100 cm3. For each milk sample the TAC determined by the ABTS test was significantly higher than the values pro- duced by the DPPH test. The above findings can be attributed to the presence of substances whose spectra overlap with DPPH• spectra. ABTS test was characterised by a higher sensitivity and repeatability of the determination of TAC in human milk compared to the DPPH test. CONCLUSIONS Comparing the calculated values for the validation parameters of both methods and taking into account the solubility of DPPH only in polar matrices, slower reaction of selected antioxidants with DPPH radical, and the presence in human milk constituents absorbing electromagnetic radiation in the absorption of DPPH be assumed that the ABTS test is more appropriate method of determining of TAC in breast milk.