Expert Review Panel for Kombucha Tea

AOAC SPDS ERP REVIEW: MAIN FORM

Submission Date

2017-09-12 15:56:34

Name

SNEH BHANDARI

E-mail

SNEH.BHANDARI@MXNS.COM

Organization

Merieux NutriSciences

Title of Method

Enzymatic method for measurement of Ethanol in Kombucha

AOAC Candidate Method Number (e.g. ALN-01)

KOM-06

Applicable SMPR

2016.001

Summary:

Enzymatic method for measurement of ethanol in Kombucha. The method is based on Megazyme’s Ethanol-assay kit (K-ETOH).

The quantification of ethanol requires two enzyme reactions; in the first reaction catalysed by alcohol dehydrogenase (ADH), ethanol is oxidised to acetaldehyde by nicotinamide-adenine dinucleotide (NAD+) (1) Ethanol + NAD+ ADH ------------  acetaldehyde + NADH + H+ However, since the equilibrium of reaction (1) lies in favour of ethanol and NAD+, a further reaction is required to “trap” the products. This is achieved by the quantitative oxidation of acetaldehyde to acetic acid in the presence of aldehyde dehydrogenase (Al-DH) and NAD+. (2) Acetaldehyde + NAD+ + H2O Al-DH-----------------  acetic acid + NADH + H+ The amount of NADH formed in this reaction pathway is stoichiometric with twice the amount of ethanol. It is the NADH which is measured by the increase in absorbance at 340 nm.

1. Does the applicability of the method support the applicability of the SMPR? If not, please explain what is missing. 2. Does the analytical technique(s) used in the method meet the SMPR? If not, please specify how it differs from what is stated in the SMPR. 3. Are the definitions specified in the SMPR used and applied appropriately in the method? If no, please indicate how the terms are used.

Yes

Yes

Yes