AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 METHOD

FOR ERP USE ONLY DO NOT DISTRIBUTE

Infant formula powder FOS/GOS based e

10 (2)

0.0308

3.60

11.7

1.7

Infant formula powder milk based e

12 (0)

0.264

5.26

14.6

3.0

a Number of laboratories considered in the evaluation (number of laboratories with data removed as outliers). 13 b Results are reported in g/100 g of product as consumed (reconstituted or RTF). 14 c Reconstitution rate: 10 g product + 90 g water. 15 d RTF = Ready-to-feed. 16 e Reconstitution rate: 25 g product + 200 g water. 17 f HorRat is not necessary applicable to methods with indefinite analytes like polymers [12] such as fructans. 18 A. Principle 19

20

Samples are reconstituted in water (if required) and further diluted until the concentration of

21

fructan in solution is such that after hydrolysis the fructose and glucose concentrations will be

22

within the range covered by the standard curve. The diluted sample is treated with a mixture of

23

sucrase and α-glucanases to hydrolyse sucrose and α -glucooligosaccharides to their constituent

24

monosaccharides. The sample is passed through a solid phase extraction (SPE) column packed

25

with graphitized carbon. Salts and monosaccharides pass through and are washed away, while

26

the fructans are retained. Fructans are released from the column using an acetonitrile solution.

27

The released fructans are hydrolysed with a fructanase mixture, and the released glucose and

28

fructose are analysed by high performance anion-exchange chromatography with pulsed

29

amperometric detection (HPAEC-PAD). The fructan content is calculated by summing the glucose

30

and 0.9 × the fructose contents measured. In some matrices, a blank correction may be necessary

31

and can be applied.

B.

Apparatus and Materials

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(a) Analytical balance. —Readability of 0.1 mg.

33

(b) pH-meter. —Readability of 0.1 pH.

34

2