Expert Review Panel for Kombucha Tea

-- The method states that blank cuvettes can either be filled with air or water, but did not present data supporting the validity of both.

3. Is there information demonstrating that the method system suitability tests and controls as specified in the SMPR worked appropriately and as expected? If no, please specify. * Yes

4. Based on the supporting information, is the method written clearly and concisely? If no, please specify the needed revisions. * The method was written clearly and concisely.

5. Based on the supporting information, what are the pros/strengths of the method? * The method is highly selective for ethanol, as an enzymatic method . It is an inexpensive and rapid method. The repeatability and recovery data were very strong.

6. Based on the supporting information, what are the cons/weaknesses of the method? * Indirect, enzymatic methods can be prone to interferences, although if there were any in this study, they were not obvious from the data.

The range of analyte concentrations did not bracket the analytical range in the SMPR

The method of preparing the sample and monitoring the reaction may have lacked sufficient clarity.

No SRM or CRM were used in the study

Only two manufacturers, from UK, and 4 products were represented in the set of kombucha matrices

No ruggedness data was presented. Changing reaction times might have been a good data set to see, considering the lack of clarity on reaction time in the method.

Storage conditions for kombucha samples were not noted.

7. Any general comments about the method? * This is a good application of an enzymatic method, and I praise the authors for the work and use of existing instrumentation that is relatively inexpensive and does not require a high level of analyst expertise to run it.