Quantitative analysis of fructans in functional foods by high-performance anion-exchange chromatography with pulsed amperometric detection

This study describes a method for determining fructans in functional foods by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The sample was first extracted with hot water. After hydrolyzed by a mixture of sucrase/β-amylase/pullulanase/maltase, the extract solution was treated with sodium borohydride to remove completely free fructose and glucose in the sample. The reaction conditions with sodium borohydride were investigated: 5 mg/mL of sodium borohydride was used, and the reaction time was 20 min. Fructans were then hydrolyzed by endo- and exo-inulinase to completely form fructose and glucose. The content of fructans was calculated based on the amount of fructose and glucose formed after fructans were hydrolyzed. The method was developed and validated on four different food matrices: milk powder, milk liquid, hard capsule, and soft capsule. The results showed that this method has good specificity and linearity (R2 > 0.99). This method also showed good accuracy and precision, with recovery values ranged between 95.0 and 103.6%, while RSD (%) values were 0.45–3.59%. The method also had a low limit of quantification and limit of detection that can quantify food samples with a small amount of fructans. The validated method has been successfully applied to determine the content of fructans in functional foods, and this method provides a valuable tool to evaluate the quality of functional food products.