Reaction kinetics of the heat-induced formation of N6-methyladenosine in milk

Abstract Ribonucleosides are milk constituents in the micromolar range that show a species-specific pattern. The levels of modified ribonucleosides such as 1-methyladenosine (m1 Ado) vary only slightly throughout lactation. The amount of 1-methyladenosine in raw bulk milk was 0.40 μmol litre−1. N6-methyladenosine (m6 Ado), which is not present in thermally untreated milk, is formed by Dimroth-rearrangement from 1-methyladenosine as a function of heating time and temperature. The rearrangement was found to be first order in the temperature range 115–150°C with holding times of 2–128 s. The z-value was determined to be 30.5°C which corresponds to a Q10-value of 2.13. The data found for the formation of 1-methyladenosine agree very closely with those found for some other thermally induced chemical reactions in milk (HMF, lactulose, thiamine loss).