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Title:   Author  item
                                            Lee, Jungminitem
                                            DURST, ROBERT - OREGON STATE UNIVERSITYitem
                                            WROLSTAD, RONALD - OREGON STATE UNIVERSITY
  Submitted to: Journal of Association of Official Analytical Chemists International
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 5/17/2005
                                    Publication  Date: 9/1/2005
                                    Citation: Lee, J., Durst, R., Wrolstad, R. 2005. Determination of total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method: collaborative study. Journal of Association of Official Analytical Chemists International.  88(5):1269-1278.Interpretive Summary: A quick and simple method to determine the amount of total anthocyanin pigment present in a given sample was tested, which was based on the Association of Analytical Communities (AOAC) official methods of analysis validation program. Based on the results obtained, the study director recommends the method to be adopted Official First Action.
                                Technical Abstract: There is no approved AOAC method for determining total anthocyanin pigments, at present. This collaborative study was conducted to determine the total monomeric anthocyanin concentration by the pH differential method. The pH differential method is a rapid and simple spectrophotometric method based on the anthocyanin structural transformation that occurs with a change in pH (colored at pH 1.0 and colorless at pH 4.5). Eleven study collaborators representing commercial laboratories, academic institutions, and government laboratories participated. Seven Youden pair materials representing fruit juices, beverages, natural colorants, and wines were tested. The repeatability relative standard deviation (RSDr) varied from 1.06 to 4.16%. The reproducibility relative standard deviation (RSDR) ranged from 2.69 to 10.12%. The Horrat values were less than or equal to 1.33 for all materials. The Study Director recommends that the method be adopted Official First Actio


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