Comparison of melatonin concentrations in raw and processed cow’s milk

Processing-dependent changes of the melatonin concentration in milk were determined using a commercial melatonin ELISA. A total of 120 milk samples, comprising ultra-high temperature processed milk (UHT), ultra-pasteurized milk with extended shelf life (ESL-HE), microfiltered milk with extended shelf life (ESL-MF), hightemperature short-time pasteurized milk (HTST), raw milk (RAW), and a commercial milk powder claiming to be melatonin-rich (night-time milk powder, NTMP) were i ncluded in the study. Raw milk and night-time milk powder had the highest melatonin concentrations, while UHT milk had the lowest. The mean melatonin concentration in raw milk was 13.6 pg/ml, but levels varied strongly between individual cows (1.3–25 pg/ml). Finally, although all processed cow milks contained statistically significant less melatonin than NTMP and raw milk they were still in the same dimension (pg/ml).