The suitability of the kit will really depend on your sample composition and will need to be validated in your laboratory.
We do have customers that have used this kit to analyse their liquid samples.
To analyse a liquid you can use 0.1 mL instead of 100 mg or 0.4 mL of sample instead of 400 mg depending on the expected fructan content and follow the extraction procedure accordingly.
If you do proceed with this method please ensure that you take note of the weight of 0.1/0.4 mL of your sample and use this weight in your calculation to obtain g/100 g value.
We would recommend to watch the presentation which is very informative Measurement of Fructan in Biological Materials Presentation.