AOAC SPIFAN Stakeholder Panel Meeting Book (March 14, 2019)

Comment Received

Response

Specifically, taurine is not a proteinogenic amino acid and is therefore only found free. The table in the SMPR should give taurine an “a” suffix to indicate that it is “determined only as free amino acids.

While taurine is not typically thought of as being a proteinaceous amino acid, total taurine methods are already published in the literature that are sometimes stated to recover taurine from peptides (AOAC 999.12 for example).

We also note that in a hydrolysate the peak is very small compared to the other amino acids. Surely, in this case then accuracy/ specificity can be readily compromised.

As taurine is present in a lower level, it benefits from the more relaxed criteria noted in the SMPR for lower levels of amino acids.

Tryptophan did not require a separate SMPR, we just left the previous SMPR intact for tryptophan since the MLT was in progress.

If tryptophan requires a separate SMPR and method, why not taurine?

Further Supporting Evidence of Bound Taurine • Bound taurine found in kidney and urine • Studies of free amino acids and related compounds in feline tissues • Harris et al. J. Biol Chem. 1954, 211:927-939 • Bound taurine in kidneys and urine as well as psoriatic lesions • Biochmemistry and physiology of taurine and taurine derivatives • Jørgen et al. Physiological Reviews. Vol 48, No. 2, 1968 • Taurine found in simple peptides • Therapeutic applications of taurine • Birdsall, Timothy C. ND. Alternative Medicine Review. Vol 3, No 2. 1998. • Official AOAC method for total taurine in pet foods • AOAC method 999.12