Quality labels for novel foods

Significance of the Topic

Galactooligosaccharides (GOS) are prebiotic carbohydrates that support beneficial gut microbiota.
Their rising inclusion in infant formulas and dietary supplements has driven demand for reliable quantification methods to meet regulatory and quality requirements.

Objectives and Study Overview

This work aims to refine the AOAC 2001.02 method for total GOS determination in food matrices.
The updated approach focuses on reducing sample preparation time, lowering reagent costs, and enhancing analytical efficiency while maintaining method robustness and sensitivity.

Used Instrumentation

• 940 Professional IC Vario ONE/HPG system configured for high-pressure gradient separations
• IC Amperometric Detector with flexiPAD waveform for sensitive detection of carbohydrates
• Metrosep Carb 2-250/4.0 anion exchange column for monosaccharide separation
• 858 Professional Sample Processor with inline dialysis for automated sample cleanup
• MagIC Net 4.0 software for instrument control, data acquisition, and compliance with 21 CFR Part 11

Methodology

Sample Preparation:

• Extraction of GOS powder and supplement samples in phosphate buffer at 80 °C for 30 minutes
• Division into two assays: one for initial sugar content and one after enzymatic hydrolysis with β-galactosidase
• Centrifugation and dilution with ultrapure water prior to injection

Chromatographic Analysis:

• Separation of galactose, glucose, and lactose on Metrosep Carb 2 column using hydroxide eluent within 18 minutes
• Post-run high-pressure gradient with acetate for column cleanup
• Detection via pulsed amperometric detection with a Thin-Layer cell to maximize signal-to-noise ratio

Data Evaluation:

• Automatic calculation of total GOS by comparing sugar concentrations before and after hydrolysis
• Calibration and recovery corrections performed in MagIC Net software

Main Results and Discussion

• Total GOS content across samples ranged from 28 to 83 g per 100 g with RSDs of 1.8–5.0% for powders and up to 10% for formula matrices
• Limits of detection reached 0.1 mg/L for galactose and 0.2 mg/L for glucose and lactose
• Recovery studies and interference tests confirmed method accuracy and robustness
• Inline dialysis improved sample purity, extending column lifetime and reducing maintenance

Benefits and Practical Applications

• Significant reduction in manual steps and reagent use compared to the original AOAC procedure
• Enhanced throughput and lower operating costs for routine quality control
• High selectivity and sensitivity without derivatization, suitable for complex food matrices
• Compliance with regulatory requirements for novel food labeling and safety

Future Trends and Potential Applications

• Integration of additional automation steps such as inline dilution and automatic calibration
• Extension of the flexiPAD approach to other oligosaccharides and polysaccharide analyses
• Real-time monitoring and multianalyte profiling using advanced IC-PAD systems
• Adoption in broader food quality, clinical nutrition, and pharmaceutical sectors

Conclusion

The improved IC-flexiPAD method builds on AOAC 2001.02 to deliver faster, cost-efficient, and reliable total GOS analysis.
This approach offers laboratories a robust tool for routine quality control, addressing the growing demand for accurate prebiotic quantification.

References

• Sangwan V, Patil M, Pandey A (2011) Galactooligosaccharides in colostrum and their bifidogenic effects. Journal of Food Science 76(4).
• Boehm G, Stahl B (2007) Prebiotics in human nutrition: a review. Journal of Nutrition 137(3 Suppl 2).
• Ziegler T, et al. (2001) Advances in total GOS determination by ion chromatography. The Column – Europe/Asia 17(02).