andaddthesameamountofacetatebuffer.pHofsolutionshouldbe4.5
±
0.05. If necessary, adjustwith0.05MKOHor 0.05MHCl.
Add sufficient amount of amyloglucosidase, taking into account
amount of starch and maltodextrins present, and enzyme
concentration (e.g., for amyloglucosidase with activity of
51Units/mg,use1mgenzymefor50mgstarch,since1Unit liberates
1mg glucose from starch). If amount of starch andmaltodextrins is
unknown, consider unknownpart of test portionas100% starch. For
paste-like products use 35 mg amyloglucosidase (with activity of
51Units/mg); for other products and starchy products use 10mg.
Incubatemixture30min inwaterbathat60
°±
2°Cwithconstant,
mild agitation. Start timing 30 min from the moment reaction
mixture reaches 60°C. Ensure that during agitation no foam forms
and no air bubbles are brought into suspension. Let cool to room
temperature and weigh (net weight is M
4
). Weigh ca 10 g first
hydrolyzate and set aside for analysis (assayA
1
).
(
2
)
Second hydrolyzation
.—To the remaining part of the first
hydrolyzate(netweightisM
5
),addsufficientamountofinulinasesolution,
taking intoaccount amount of fructanpresent in test portionandenzyme
concentration(e.g.,forFructozymeSP230
®
withactivityof1.8Units/mg,
use 56mg enzyme for 100mg fructan, since 1Unit hydrolyzes 1mg
fructan; guide value 150 mg Fructozyme). If amount of fructans is
unknown, consider unknownpart of test portionas100% fructan.
Incubate again 30min inwater bath at 60
° ±
2°Cwith constant,
mild agitation. Start timing 30 min from the moment reaction
mixture reaches 60°C. Ensure that during agitation no foam forms
and no air bubbles are brought into suspension. Let cool to room
temperature andweigh (net weight isM
6
; assayA
2
)
G. DeterminationofMono- andDisaccharides
(
a
)
Preparation of extract and hydrolyzates for HPAEC–PAD
analysis
.—Dilute homogenizedmixture from
E
, and first and second
hydrolyzates from
F
, so that glucose, fructose, and sucrosecontents are
withinconcentrationrangeofsugarsworkingstandardsolutions,andadd
glucoheptose internal standard solution as follows:
(
1
)Dilute2.0gglucoheptose internalstandardsolution,
C
(
q
),and
amount of homogenized mixture (M
7
), within range of glucose
standard solution, to 100 gwithH
2
O (assayA
0
).
(
2
)Dilute2.0gglucoheptose internalstandardsolution,
C
(
q
),and
amount of first hydrolyzate (M
8
),within range of fructose standard
solution, to 100 gwithH
2
O (assayA
1
).
(
3
)Dilute2.0gglucoheptose internalstandardsolution,
C
(
q
),and
amount of second hydrolyzate (M
9
), within range of sucrose
standard solution, to 100 gwithH
2
O (assayA
2
).
ã
2013AOAC INTERNATIONAL
Figure 997.08. Flow diagramof extraction and
hydrolysis for determinationof fructans in foodsby ion
exchangechromatography.
Table 997.08D. Guide values for dilutions for HPAEC-PAD fructan analysis for amountsof A
0
, A
1
, andA
2
tobediluted to100gwith
H
2
O
Product
gM
1
gA
0
(M
7
)
gA
1
(M
8
)
gA
2
(M
3
)
Low-fat spread (8% inulin)
12.5
5
10
1
Cheese or cheese spread (5% inulin)
20
10
0.5
1 and 5
Chocolate (10% inulin)
10
1 and 10
4
1
Chocolate paste (10% inulin)
10
0.2 and 10
2
0.5
Bakery products (5% oligofructan)
5/250
0.5 and 25
4
2
Dry ice-mix
a
(15% oligofructan)
7
0.5 and 2
4
1
Vegetables (5% inulin)
20
10
10
1
Dairy products (3% oligofructan)
30
1.5 and 10
3
1
Fruit preparates
b
(20% oligofructan)
5
2
1
0.25
Cereals (10% inulin)
5/250
15
1.5
3
Confectionery, sweet (35%oligofructan)
2.5
1
2
2
a
A powder for ice cream preparation.
b
Marmaladeand fructan.
FOS-01
FORWORKINGGROUP/ERPUSEONLY
DONOTDISTRIBUTE
