Trimethylamine Responsible for Fishy Flavor in Milk from Cows on Wheat Pasture

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Abstract
A method was developed to quantify trimethylamine and methylamine by gas- liquid chromatography in steam distillates of milk. There was a decrease in milk flavor scores and a proportionate increase in concentrations of trimethylamine to 4.08 ppm and of methylamine to 57.5 ppm in milk from two cows on winter wheat pasture for 8 days. Flavor scores of 10 commercial milk samples ranged from 34.0 to 38.3, and trimethylamine and methylamine concen- trations ranged from .26 to 1.28 and 4.85 to 14.63 ppm - well below the estimated flavor thresholds in milk as determined by triangular taste tests. The flavor tl:treshold for trimethylamine was approx- imately 2 ppm, whereas methylamine was not organoleptically detectable at 80 ppm. The fo.rmer at 4 ppm decreased flavor scores from 36.6 (normal milk) to 32.0 while 40 ppm of the latter gave a score of 37.0. Adding trimethylamine elicited fishy and unclean flavors. It. therefore, is responsible for the fishy flavor characteristic of milk produced on wheat pasture.