Analysis of Dietary Fiber in Functional Beverage Using Automated Dietary Fiber Analyzer Combined with Integrated HPLC

Importance of the Topic

Dietary fiber plays a critical role in human health by supporting digestive function, weight management, and reducing risks of cardiovascular disease, diabetes, and certain cancers. Accurate quantification of both insoluble and soluble fiber fractions, especially low-molecular-weight soluble dietary fiber (SDFS), is essential for food manufacturers, quality control laboratories, and nutrition researchers.

Objectives and Study Overview

This study presents a streamlined workflow for analyzing dietary fiber in functional beverages enriched with resistant dextrin. It integrates an automated dietary fiber analyzer based on AOAC 2022.01 enzymatic–gravimetric protocols with high-performance liquid chromatography (HPLC) to quantify SDFS precisely and efficiently.

Methodology

• Sample Pretreatment: 10 g beverage powder undergoes sequential enzymatic digestion using pancreatic α-amylase and amyloglucosidase (4 h at 37 °C), followed by protease treatment (30 min at 60 °C).
• Filtration and Precipitation: Insoluble fiber is isolated on disposable filter bags; soluble polymeric fiber (SDFP) is precipitated with ethanol. Filtrate containing SDFS is desalted, concentrated, and prepared for HPLC.
• HPLC Analysis: Separation on two Shim-pack SUR-Na columns (250 × 7.8 mm, 8 µm) at 80 °C with water mobile phase at 0.5 mL/min. Detection by differential refractive index.
• Quantification: Diethylene glycol (DEG) serves as internal standard. Response factors calculated from glucose/DEG standards; SDFS content expressed per 100 g sample.

Used Instrumentation

• Automated Dietary Fiber Analyzer (ANKOM Technology) with disposable filter bags.
• HPLC System: Shimadzu LC-2070 pump, Shim-pack SUR-Na guard and analytical columns, RID-20A refractive index detector.
• Megazyme Rapid Integrated Total Dietary Fiber Assay Kit (K-RINTDF) reagents and standards.

Main Results and Discussion

The measured SDFS in three functional beverages ranged from 1.10 to 1.46 g/100 g, corresponding to 102–110 % of the labeled resistant dextrin content. Spike-and-recovery tests yielded recoveries between 92 % and 106 %, demonstrating high accuracy and precision. Chromatograms showed clear separation of SDFS, glucose, and internal standard peaks.

Benefits and Practical Applications

• Automated workflow reduces manual labor, risk of human error, and processing time by eliminating glassware preparation, ashing, and repeated filtrations.
• Disposable filter bags eliminate cross-contamination and simplify cleanup.
• Integrated HPLC enables reliable quantification of low-molecular-weight fibers often underestimated by traditional gravimetric methods.

Future Trends and Applications

Emerging trends include expanding automated fiber analysis to complex food matrices, coupling with mass spectrometry for structural elucidation of oligosaccharides, and developing standardized protocols for novel dietary fibers. Integration with digital data management can further enhance throughput and traceability in food quality control.

Conclusion

The combined automated enzyme-gravimetric and HPLC approach provides a robust, high-throughput solution for comprehensive dietary fiber profiling in functional beverages. It delivers accurate measurements of insoluble, polymeric soluble, and low-molecular-weight soluble fibers with minimal labor and high reproducibility.

References

1. D. Mudgil, S. Barak, Int. J. Biol. Macromol., 61 (2013), 1–6
2. W. Hong et al., Nutrition, Vol. 111 (2023), 112035
3. D. Mudgil et al., J. Anim. Sci., 98 (2020), Skaa303
4. AOAC Official Method 2022.01, Rapid Integrated Enzymatic-Gravimetric-Liquid Chromatography
5. ANKOM Technology, TDF Dietary Fiber Analyzer