Identification of hydrolyzed inulin syrup and high-fructose corn syrup in apple juice by capillary gas chromatography - PVM 4 : 1999

A peer-verified, gas chromatographic (GC) method is presented for the ident ification of hydrolyzed inulin syrup (HIS) and high-fructose corn syrup (HF CS) in apple juice. The procedure involves determining the Brix value of th e apple juice or apple juice concentrate and preparing a dilution of the te st sample to 5.5 degrees Brix. A 100 muL aliquot of the 5.5 degrees Brix te st solution is then freeze-dried in a GC autosampler vial. The su,oars in t he freeze-dried residue are converted to trimethylsilyl derivatives, by the addition of an appropriate silylation reagent, and the vial is heated at 7 5 degreesC for 30 min. After derivatization, the solution is introduced int o a gas chromatograph where the analytes are separated on a 30 m, 0.25 mm i d DB-5 column. The method can use hydrogen, helium, or nitrogen as the carr ier gas. The analytes and marker compounds are measured by use of a flame i onization detector. Commercial apple juice concentrates were diluted with o ne of the 2 syrups at 2 revels. Dilution was ascertained by the presence of retrograde sugar markers found in the 2 sugar syrups. An 3 laboratories in volved in the study were able to identify the correct diluent in the blind, randomly coded, apple juice test portions. The levels of dilution in the t est portions were 0, 6.9% (HIS), 16.0% (HIS), 8.1% (HFCS), and 17.0% (HFCS) . No false positive results were reported. Quantitative conclusions can be drawn when the same syrup is used for dilution and as a reference standard.