Changes in the free amino and other nitrogen compounds in stored beef muscle

Changes in the levels of 21 amino compounds, ammonium‐N and urea‐N. during the storage of fresh beef at various temperatures have been investigated. The meats were also subjected to bacteriological analysis. Glutathione and glutamine were found to decrease in the meats during storage, while most other amino‐acids, notably glutamic acid and tryptophan, increased. The increase in glutamic acid appeared to be related to the microbial numbers in the meats. On the other hand, the increase in tryptophan seemed directly related to the time and temperature of storage. There was an initial increase in urea‐N followed by a gradual disappearance of this compound from the stored meats. Ammonium‐N did not rise significantly until the stage of incipient spoilage had been reached.