Background: The objective of this study was to evaluate whether addition of milk to green, black and decaffeinated black teas alters their antimutagenic activity.
Materials and methods: Two model mutagens were used, the direct-acting N'-methyl-N'-nitro-nitrosoguanidine (MNNG) and the indirect-acting 2-amino-3-methylimidazo-[4,5-flquinoline (IQ), and their mutagenic activity was determined in the Ames test, in the presence of tea and milk/tea mixtures. Solids from the milk/tea mixtures were removed by centrifugation and the supernatant analysed by HPLC for individual catechins and gallic acid in green tea, and thearubigins, theaflavins and flavonol glycosides in black teas.
Results: Addition of skimmed milk to all the teas failed to influence their antimutagenic activity towards the two mutagens. Addition of milk to green tea resulted primarily in loss of (-)-epigallocatechin gallate whereas in the black teas it primarily reduced theaflavins levels.
Conclusion: The antimutagenic activity of green and black teas is not modulated by the presence of skimmed milk, even at high concentrations.