6. AOACSPIFANMethods-2018Awards

238

520 F eng et al .: J ournal of AOAC I nternational V ol . 100, N o . 2, 2017

Conclusions and Recommendations The SDS-CGE method is capable of accurately determining the ratio of whey to casein in infant formulas manufactured using different whey ingredients. Because whey and casein proteins, as groups, have distinct migration times, the measurements will not miss individual proteins. As a consequence, absolute quantification of individual or total proteins is not necessary. It was recommended that the method be further validated by conducting a multilaboratory study. This would generate valuable method performance data, including RSD R , further enhancing the potential of this method for use in a routine QC environment. Table 10. Comparison of the area percentage of whey protein between the times after compounding and after spray-drying during the processing of formula trial samples Area CF Whey Casein Whey/casein Before processing 306543 257994 1.19 1.11 After processing 337097 314112 1.07 Table 9. Measured results of whey protein as the area percentage of caseins for different batches of SMP samples from different suppliers by SDS-CGE and the calculated area CF of whey proteins to caseins Whey as percentage of casein (mass) Literature (4, 5) 26.9 Whey as percentage of casein (area) Lot No. n a Avg. SD EY06 3 20.02 0.58 CY25 2 20.62 0.35 DY06 2 20.25 0.17 DY19 4 20.58 0.30 DY21 5 20.44 0.81 DY29 b 24 21.32 1.00 M023 2 18.84 0.09 M075 2 22.26 1.02 M208 2 21.40 1.16 MSK 1 22.27 SMP DN1 1 21.53 SMP DN2 1 21.34 SMP DN3 1 19.79  Avg. c 20.81  SD d 0.99  CV, % 4.78  CF 1.29  Process impact e 1.11  Final CF 1.4 a n = Number of measurement. b  Four different batches of capillaries with two different sets of reagent kits on 12 different days. c  Avg. = Average. d  SD = Standard deviation. e  Obtained by evaluating processed and finished infant formula product (Table 10).

Table 11. Measured whey protein content in 43 different infant formulas made by both local and international manufacturers

Measured whey, %

Manufacturer whey claim, % a

Avg. 59.9 70.7 56.4 41.8 64.7 59.6 59.7 65.9 63.2 71.2 62.9 57.3 64.4 63.2 63.7 20.2 69.0 62.2 65.5 70.6 61.5 62.4 67.5 70.2 65.0 67.3 62.9 59.3 64.9 62.4 64.4 64.0 60.5 70.0 42.1 57.4 58.9 66.4 62.7 60.0 60.7 22.6 22.5

SD

% of claim

Product

n

1

60 70

12 18 12 18 12

0.50 0.34 0.80 0.47 0.30 0.23 0.66 0.41 0.34 0.84 1.15 0.09 0.10 0.27 1.26 0.92 1.03 1.69 1.03 1.51 1.43

100 101

2 b

3 4

60–65 (62.5)

90

40 65 60 60 65 65 70 60 60 60 60 60 70 65 65 70 61 70 70 70 60 60 60 62 60 61 60 60 70 60 60 64 60 60 60 21 21

104

5 c

99 99 99

6 7 8 9

4 4 4 3 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2

101

97

10 b 11 d

102 105

12 13 14 15 16 17 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

95

107 105 106

N/L e

99 96

18 c

101 101 101

89

Pass f

>60 (65)

100

93

112 105

99

105 104 106 107 100 100

N/L

96 98

104 105 100 101 108 107

L1 g L2 g

2.43 1.71

a  Numbers in parentheses represent value considered. b  CGMP-reduced sweet whey formula. c  α-Lac-enriched formula. d  LF-enriched formula.

e  N/L = Not labeled. f  Conform to claim. g  The claim of 21.2% comes from the value for SMP, not a real claim.