Table 1 Overview of the results.

From: Interlaboratory validation of an optimized protocol for measuring α-amylase activity by the INFOGEST international research network

 

α-amylase M

α-amylase S

Pancreatin

Human saliva

20 °C

37 °C

20 °C

37 °C

20 °C

37 °C

20 °C

37 °C

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Activity

(Mean ± SD)

CV

(%)

Panel A – Amylase activities1 as reported by each participating lab

 Lab A

116.5

 ± 

8.5

7.3

487.3

 ± 

48.4

9.9

7.9

 ± 

0.2

2.2

28.0

 ± 

4.3

15.4

68.1

 ± 

7.6

11.1

240.1

 ± 

23.8

9.9

184.9

 ± 

15.4

8.3

828.4

 ± 

97.5

11.8

 Lab B

107.3

 ± 

12.7

11.8

340.6

 ± 

11.5

3.4

5.5

 ± 

0.3

5.3

17.7

 ± 

0.5

3.0

57.3

 ± 

1.5

2.6

169.8

 ± 

7.6

4.5

271.8

 ± 

12.7

4.7

702.9

 ± 

72.8

10.4

 Lab C

122.7

 ± 

6.7

5.5

409.0

 ± 

51.7

12.6

7.9

 ± 

0.9

10.8

22.7

 ± 

1.9

8.3

58.8

 ± 

6.4

10.8

210.3

 ± 

23.4

11.1

299.5

 ± 

29.4

9.8

851.1

 ± 

141.1

16.6

 Lab D

67.3

 ± 

15.5

22.9

289.4

 ± 

10.6

3.7

5.4

 ± 

0.5

8.8

17.6

 ± 

0.9

5.2

56.5

 ± 

8.6

15.2

158.8

 ± 

12.5

7.8

212.0

 ± 

26.7

12.6

669.7

 ± 

89.0

13.3

 Lab E

105.8

 ± 

15.9

15.0

376.7

 ± 

57.3

15.2

6.3

 ± 

1.0

15.3

16.6

 ± 

2.9

17.4

53.7

 ± 

6.2

11.5

174.5

 ± 

23.4

13.4

298.2

 ± 

33.6

11.3

914.4

 ± 

133.1

14.6

 Lab F

–

395.6

 ± 

44.7

11.3

–

25.1

 ± 

2.4

9.5

–

190.1

 ± 

2.9

1.5

–

809.8

 ± 

59.5

7.3

 Lab G

–

366.6

 ± 

14.7

4.0

–

23.2

 ± 

1.2

5.3

–

210.1

 ± 

4.7

2.25

–

1082.6

 ± 

109.9

10.2

 Lab H

–

439.9

 ± 

41.0

9.3

–

26.1

 ± 

1.5

5.8

–

225.0

 ± 

9.0

3.99

–

895.4

 ± 

95.2

10.6

 Lab I

–

363.0

 ± 

25.2

7.0

–

15.1

 ± 

0.2

1.0

–

220.3

 ± 

27.0

12.3

–

1109.0

 ± 

201.6

18.2

 Lab J

–

392.0

 ± 

39.1

10.0

–

20.7

 ± 

1.5

7.4

–

200.0

 ± 

4.0

2

–

798.7

 ± 

54.6

6.8

 Lab K

–

328.3

 ± 

39.5

12.0

–

26.1

 ± 

1.3

5.0

-

195.7

 ± 

10.7

5.5

–

728.1

 ± 

18.8

2.6

 Lab L

–

479.5

 ± 

61.4

12.8

–

29.2

 ± 

2.6

8.9

–

282.8

 ± 

12.4

4.4

–

970.1

 ± 

170.1

17.5

 Lab M

–

31.5

 ± 

0.52

1.72

–

45.2

 ± 

4.42

9.72

–

352.3

 ± 

45.32

12.92

–

1046.7

 ± 

61.8

5.9

Activity (Mean ± SD)

103.7X ± 21.4

389.0B ± 58.9

6.6Z ± 1.2

22.3D ± 4.8

58.9Y ± 5.5

206.5C ± 33.8

253.3W ± 52.1

877.4A ± 142.7

Activity in IU3 (Mean ± SD)

 

377.3 ± 57.1

 

21.6 ± 4.7

 

200.3 ± 32.8

 

851.1 ± 138.4

Panel B – Assay repeatability and reproducibility

 Repeatability (CVr, %)

14.0

10.0

9.6

8.9

11.0

7.7

9.7

12.5

 Reproducibility (CVR, %)

20.6

15.1

18.8

21.3

9.3

16.4

20.6

16.3

Panel C – Relationship between activities measured at 37 °C vs. 20 °C

 Ratio of activity at 37 °C vs. 20 °C (Mean ± SD)4

3.7 ± 0.5

3.1 ± 0.4

3.2 ± 0.3

3.2 ± 0.7

Global average5 of the activity ratios between 37 °C and 20 °C = 3.3 ± 0.3 (95% CI: 2.9 to 3.7)

  1. 1Amylase activity unit definitions: assay at 20 °C—one unit liberates 1.0 mg of maltose from starch in 3 min at pH 6.9 and 20 °C; assay at 37 °C—one unit liberates 1.0 mg of maltose from starch in 3 min at pH 6.9 and 37 °C.2Excluded from calculation of activity mean and SD, CVr, CVR and from the statistical analysis. 3Conversion of mean α-amylase activities obtained using the newly optimized protocol (at 37 °C) into International Units (IU) by multiplying activity values based on Bernfeld’s original definition by the conversion factor 0.97. 4Average of the ratios of activity at 37 °C vs. 20 °C reported by laboratories A to E for each test product. 5Average of the ratios of activity at 37 °C vs. 20 °C of all test products as reported by laboratories A to E.
  2. A–DWithin a row, denote statistically significant differences between the products tested at 37 °C (p < 0.0001). W-Z Within a row, denote statistically significant differences between the products tested at 20 °C (p < 0.0001).
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