3
4.2.10 Sodium hydroxide solution (200mmol/L): 10.4mL sodium hydroxide solution (50%) is
diluted to 1000mLusingwater and shaken under the protection of nitrogen gas.
4.2.11 Sodium hydroxide (150mmol/L) sodium acetate (500mmol/L)mixed solution:
41 g
(with an accuracyof 0.01 g) sodium acetate(anhydrous) is dissolved in nearly500mLwater and
mixedwith 7.8mL50% hydroxide solution(sodium), then the solution is diluted to 1000mL
usingwater and shaken under the protection of nitrogen gas.
4.3Standard substances
D-fructose standard substance: purity≥99%, Sigma.
4.4 The preparation of standard solution
4.4.1 Fructose stock solution (2000mg/L): 0.05g (with an accuracyof 0.1mg) fructose is
placed in a small beaker and dissolved in nearly10mL80
℃
hotwater, after dissolve, the
solution is diluted to 25mL in a volumetric flask and shaken, which can be stored for onemonths
at 4
℃
.
4.4.2 Fructose intermediate solution (80.0mg/L): 1mL fructose stock solution is diluted to 25
mL in a volumetric flask usingwater, which ismade upwhen used.
4.4.3 Fructoseworking standard solution: certain fructose intermediate solution ismade up
to 0.800mg/L, 1.60mg/L, 4.00mg/L, 8.00mg/L, 16.0mg/Lworking standard solutions using
water.
5 Analysis process
5.1 Preparation of test solutions
5.1.1 Sample pretreatment
5.1.1.1 Solid samples: samples are ground andmixed, set-aside.
5.1.1.2 Liquid samples: samples are shaken and set-aside.
5.1.2 Extraction
1g~5g (with an accuracyof 0.1mg, contains at least 25mg fructan) homogenized sample is
placed in a 150mLerlenmeyer flask andmixedwith50mL80
℃
hotwater, shaken by a
rotating speed of 150 r/min for 15minutes at 80
℃
in awater bath shaker, then the erlenmeyer
flask is taken out and cooled to room temperature, then transfer the solution into a 100mL
volumetric flask, rinse the erlenmeyer flask three timeswithwater, dilute the solution to themark
and shake, filter the solution using filter paper or centrifuge the solution, the filtrate or
supernatant is set-aside.
Beverages andwines containing carbondioxide: 1g~5g (with an accuracyof 0.1mg,
contains at least 25mg fructan) homogenized sample is placed in a 50mLbeakerwhich is then
placed on a 100
℃
hot plate, the sample is heated and evaporated to be nearlydry, transfer it
into a 100mLvolumetric flask, rinse the beaker three timeswithwater, dilute the solution to the
mark and set-aside.
Transfer 200μLbackup sample solution into a 10mLglass tubewith plug, add 400μL
sucrase (4.5U/mL)/β-amylase (23U/mL)/pullulanase (4.5U/mL)/maltase (45U/mL) solution
(appropriately increase the amount of enzyme solution if the sucrose content level is relatively
high in sample solution. If the 200μLbackup sample solution containing80μg sucrose, 400μL
enzyme solution is enough. But if sucrose content ismore than80μg, for each additional 10μg
FOS-02
FORWORKINGGROUP/ERPUSEONLY
DONOTDISTRIBUTE
