Determination of Food Sugars in Fruit Juice Using Refractive Index Detection and BEH Amide Column Chemistry

Importance of the Topic

Accurate determination of sugars in fruit juices is essential for quality control, regulatory compliance, and consumer health. Monitoring fructose, glucose, and sucrose levels helps verify fruit variety authenticity, prevents adulteration, and supports labeling claims for premium juices.

Objectives and Overview of the Study

This work presents a simple, rapid, and cost-effective HPLC method using isocratic elution on an XBridge BEH Amide XP column coupled with refractive index detection. The aim was to quantify key sugars in various commercial fruit juices with minimal sample preparation and under an eight-minute analysis time.

Methodology and Instrumentation

• Sample preparation: Centrifugation to remove pulp and particulates followed by a 1:50 dilution in water/acetone.
• Chromatographic conditions: Isocratic elution using water/acetone modified with triethylamine on a 4.6×100 mm, 2.5 µm XBridge BEH Amide XP column.
• Detection: Waters Alliance HPLC System equipped with a 2414 refractive index detector featuring a thermally isolated optics bench for signal stability.

Main Results and Discussion

Complete baseline separation of five sugars (fructose, glucose, sucrose, maltose, lactose) was achieved in less than eight minutes. Calibration with six concentration levels enabled precise quantification. Analysis of orange, apple, white grape, and pineapple juices demonstrated distinct sugar profiles, highlighting the method’s versatility and sensitivity.

Benefits and Practical Applications

• No column re-equilibration between injections due to isocratic conditions, increasing sample throughput.
• Amide-based stationary phase avoids Schiff base formation, extending column lifespan and ensuring accurate quantification.
• Minimal sample preparation and reliable RI detection reduce operational costs and complexity.

Future Trends and Potential Applications

Potential enhancements include coupling amide columns to mass spectrometry for improved sensitivity, integration of automated sample preparation, development of high-throughput platforms for on-line quality control, and exploration of novel stationary phases for enhanced selectivity.

Conclusion

The described HPLC-RI method delivers a fast, robust solution for comprehensive sugar profiling in fruit juices. It meets industry requirements for speed, accuracy, and cost efficiency while avoiding limitations of traditional amine chemistries.

References

1. Benvenuti ME, Burgess J. Determination of Food Sugars in Fruit Juice Using Refractive Index Detection and BEH Amide Column Chemistry. Waters Corporation, 2012.