AOAC SPIFAN WPC ERP-Final Action Review (Nov. 2017)

2016.15 (Nov. 2017) - WPC-31 MLT-Final Action Review

FOR ERP USE ONLY DO NOT DISTRIBUTE

formulas, identify the β-casein peak according to the SMP eGram and set the casein integration start time just before this peak. For all samples, set the end time at the valley between the end of the κ-casein peak and the Ig H and BSA peak (about 7.0 minutes after the 10 kDa internal standard). j) If using 32 Karat software from Beckman, the data processing steps are described in the Appendix. F. Calculations a) Separately sum peaks in three regions: two at each end of the eGram (lower molecular weight and higher molecular weight 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) Calculation of whey protein content: The whey protein content is calculated using the following equations: Whey protein % = A w,c A w,c + A cn ×100 (1) 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 1.4 = correction factor to account for the difference between the mass-to- area ratio of whey and casein proteins Note: the peaks in the egrams may shift backwards gradually from the beginning of the run to the end of the run. The internal standard peak is used to correct the migration times for all the peaks in the egram.

Figure 2016.15A: Buffer tray configuration (for Beckman instrument)