AOAC SPSFAM PAC ERP

II. Review of the Method Only 1. Does the applicability of the method support the applicability of the SMPR? If not, please explain what is missing.

This method does not support the applicability of the SMPR because:

1. The method is precise button accurate. The method severely underestimates the amount of PAC in cranberries because the A2 dimer is an inappropriate standard because the stoichiometry of reaction of the A2 dimer is significantly different than the mixture of oligomers of higher degree of polymerization that are present in cranberries. 2. The tile of the method is misleading because the DMAC reagent reacts with all proanthocyanidins not just a type PACs. Feliciano et al (2012) showed that although the kinetics of reaction of A2 and B2 dimers were different, there was essentially no difference between the two standards when the absorbance at Tmax was used to estimate PAC concentration and, both standards severely underestimate PAC content. This method does not meet the SMPR because it does not quantify total proanthocyanidin content as the sum of all extractable oligomers and polymers present in cranberries because the method uses an inappropriate standard.

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. 4. Does the method, as written, contain all appropriate precautions and warnings related to the method's reagents, components, instrumentation, or method steps that may be hazardous? If no, please suggest wording or option(s). III. Review of Supporting Information 1. Are the definitions specified in the SMPR used and applied appropriately in the supporting documentation (manuscripts, method studies, etc...)? If not, please explain the differences and if the method is impacted by the difference.

The method does not use the definitions in the SMPR because the SMPR clearly states extractable oligomers greater than DP2. However the authors make no attempt to distinguish between the A2 dimer and the oligomers of higher of higher DP. Most of the proanthocyanidins in cranberries have a DP higher than 2 and also contain more than one A type interflavan bond.

Perhaps some concern regarding H2SO4.

III. Review of Information in Support of the Method

The references are inadequate because the authors ignore the publication of Feliciano et al (2012). This publication clearly shows the problem of using PAC dimers as standards for the DMAC assay. This overbite is a serious concern with the the authors intent for this method and needs to be addressed in the the discussion of the review board. The problem of standards and its interaction with degree of polyerizatio of PAC is well know and needs to be address in any method that we adopt.