AOAC Final Action Methods in 2018

F. Calculations (a)  Separately sum peaks in three regions: two at each end of the eGram (lower MW and higher MW whey proteins) and one in the middle. The middle region corresponds to casein proteins ( A cn ), and the two others are summed together to obtain whey proteins ( A w ). (b)  Whey protein content is calculated using the following equations: Figure 2016.15D. eGram of typical infant formula. LowMWWhey

High MWWhey

Casein

Note : Peaks in the eGrams may shift backwards gradually from the beginning of the run to the end of the run. The IS peak is used to correct migration times for all the peaks in the eGram. References: (1) A1973A Application Information of Protein Characterization , Beckman Coulter, Fullerton, CA, USA

(2) A5190AD Application Guide of PA 800 plus Pharmaceutical Analysis System , Beckman Coulter, Fullerton, CA, USA J. AOAC Int . 100 , 510(2017) DOI: 10.5740/jaoacint.16-0344 (First Action) J. AOAC Int . 101 , 1566(2018) DOI: 10.5740/jaoacint.18-0057 (Final Action) AOAC SMPR 2012.002 J. AOAC Int . 96 , 501(2013) DOI: 10.5740/jaoac.int.SMPR2012.002

A A A w,c w,c

(1)

u 100

Whey protein%=

cn

A w,c = A w × 1.4

(2)

where A w = total integrated areas of whey components; A w,c = corrected integrated area of whey components; A cn = integrated area of casein components; and 1.4 = CF to account for the difference between the mass-to-area ratio of whey and  casein proteins.

Posted: February 2018, October 2018

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