Dietary Fiber Analysis: A Brief History

In this section:

• Identifying Dietary Fiber

• Early Methodology

• Addressing Resistant

• Starch References

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methodology in Dietary Fiber analysis >>

Having spent a significant part of their careers studying populations in sub-Saharan Africa, they reached the conclusion that the lack of unprocessed, high fiber foods in typical Western diets contributed to a higher incidence of certain conditions including heart disease and colorectal cancer.^2-4 Hugh Trowell is credited with developing the first acceptable definition of dietary fiber in 1974.^5,6

“Dietary fiber consists of the remnants of edible plant cells, polysaccharides, lignin, and associated substances resistant to digestion by the alimentary enzymes of humans.”

Early Methodology 

Following on from this a number of research groups began to focus on improving the methodology available for the measurement of dietary fiber content; Southgate,⁷ Theander,⁸ Schweizer,⁹ Furda,¹⁰ Heckman,¹¹ Baker,¹² and Asp¹³ being the major contributors at this time. Their goal was to develop a method of analysis that could be used to quantify dietary fiber as defined by Trowell.

The Prosky Method (1985) and Lee Method (1991)

By 1985, Leon Prosky had successfully led a collaborative effort to reach consensus within the scientific community on dietary fiber methodology. This was accomplished through an interlaboratory study that resulted in the acceptance of AOAC 985.29/AACC 32.05 as the reference method for the analysis of dietary fiber.^14,15

This method was widely welcomed by the food science community, serving as a reliable, reproducible analytical tool for the food and beverage industries. A series of related methods for the measurement of dietary fiber followed and were also approved by AOAC. The most useful of these was a simple extension of the Prosky method which allowed the measurement of soluble and insoluble dietary fiber separately (Lee method – AOAC 991.43).¹⁶

Limitations in the Prosky/Lee Methodology

Scientific surveys in the early 1990s began to highlight a deficiency in the definition of dietary fiber.^17,18 A growing body of evidence existed for the inclusion of resistant starch and non-digestible oligosaccharides in total dietary fiber because these food ingredients exhibited many of the health benefits claimed for dietary fiber. These components were not measured by the “gold standard” Prosky method (AOAC 985.29) or its soluble/insoluble extension – AOAC 991.43. The analytical community responded to this challenge by developing both entirely new methods and extensions to existing methods. For example, dietary fiber including non-digestible oligosaccharides could be measured using the Matsutani method (AOAC 2001.03)¹⁹, but the quantification of resistant starch posed a more serious problem.

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Addressing Resistant Starch

The Prosky method (AOAC 985.29) could never be used for the measurement of resistant starch because the harsh incubation conditions (100^oC, pH 8.2) during enzymatic hydrolysis ensured that the starch content in the sample was completely gelatinised removing any ‘resistant’ component.

Measuring Resistant Starch in isolation

Throughout the 1980s, a number of research groups (Champ,²⁰ Berry,²¹ Cummings,²² and Muir and O’Dea²³) turned their attention to a method for the measurement of resistant starch and sought to develop a method using pseudo-physiological incubation conditions for the required enzymatic digestion step. McCleary et al.²⁴ ultimately developed a method employing pancreatic α-amylase in place of bacterial α-amylase at pH 6, 37^oC, which could successfully be used to reproducibly measure resistant starch. This was the only resistant starch method that survived the thoroughness of an interlaboratory evaluation and was accepted by AOAC as an official method (AOAC 2002.02).²⁵

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Following intensive research, it was shown that the incubation step developed for the resistant starch method (with very minor modifications) was also suitable for the measurement of HMWDF.

The mild, physiologically relevant conditions employed ensured that the starch present in a sample was not gelatinised and could be accurately measured as a component in dietary fiber. The precipitation step for the isolation of HMWDF was used as in AOAC 985.29 to maintain the previous molecular weight cut-off and the HPLC analysis of the filtrate following this precipitation was performed as described in the Matsutani method (AOAC 2001.03) to guarantee correct measurement of non-digestible oligosaccharides. The amalgamation of all of these features resulted in the McCleary method²⁶ for Integrated Total Dietary Fiber (AOAC 2009.01)²⁷ and its soluble/insoluble method extension (AOAC 2011.25).²⁸ These methods were refined further to develop the much faster RINTDF method for Rapid Integrated Total Dietary Fiber measurement (AOAC 2017.16).

RINTDF is now the only method that correctly measures all components of dietary fiber as defined by CODEX Alimentarius.

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References 

1. Hiplsley, E. H. (1953).  Dietary “Fibre” and Pregnancy Toxaemia.  Br.Med. J., 2(4833), 420-422. Link to article
2. Trowell, H. (1972).  Crude fibre, dietary fibre, and artheroschlerosis.  Atheroscler., 16(1), 138-140. Link to article
3. Trowell, H. (1972).  Ischemic heart disease and dietary fibre.  Am. J. Clin. Nutr., 25(9), 926-932. Link to article
4. Burkitt, D. P., Walker, A. R. P. & Painter, N. S. (1972).  Effect of dietary fibre on stools and transit times and its role in the causation of disease.  Lancet, 300(7792), 1408-1411. Link to article
5. Trowell, H. C. (1974).  Definition of dietary fibre.  Lancet, 303(7856), 503. Link to article
6. Trowell, H. C., Southgate, D. A. T., Wolever, T. M. S., Leeds, A. R., Gassull, M. A. & Jenkins, D. J. A. (1976).  Dietary fiber redefined.  Lancet, 307(7966), 967. Link to article
7. Southgate, D. A. T. (1977).  The definition and analysis of dietary fibre.  Nutr. Rev., 35(3), 31-37. Link to article
8. Theander, O. & Aman, P. (1979).  Studies on dietary fibres. I. Analysis and chemical characterization of water-soluble and water-insoluble dietary fibres.  Swedish J. Agric. Research, 9(3), 97. Link to article
9. Schweizer, T. F. & Wursch, P. (1979).  Analysis of dietary fiber.  J. Sci. Food Agric., 30(6), 613-619. Link to article
10. Furda, I. (1981).  Simultaneous analysis of soluble and insoluble dietary fiber. “The Analysis of Fiber in Foods”,  (W. P. T. James and O. Theander, Eds.), Marcel Dekker, New York, NY. Link to book
11. Heckman, M. M. & Lane, S. A. (1981).  Comparison of dietary fiber methods for food.  J. AOAC Int., 64(6), 1339-1343. Link to article
12. Baker, D. (1981).  Notes on the neutral detergent fibre method. “The Analysis of Fiber in Foods”,  (W. P. T. James and O. Theander, Eds.), Marcel Dekker, New York, NY. Link to book
13. Asp, N-G., Johansson, C-G., Hallmer, H. & Siljestrom, M. (1983).  Rapid enzymatic assay of insoluble, and soluble dietary fiber.  J. Agric.Food Chem., 31(3), 476-482. Link to article
14. Prosky, L., Asp, N-G., Furda, I., DeVries, J. W., Schweizer, T. F. & Harland, B. F. (1985).  Determination of total dietary fiber in foods and food products: Collaborative study.  J. AOAC Chem., 68(4), 677-679. Link to article
15. AOAC Official Method 985.29, Total Dietary in Foods-Enzymatic-Gravimetric Method. (1995).  Official Methods of Analysis, 16th ed. AOAC International, Gaithersburg, MD. Link to article
16. AOAC Method 991.43, Total, Insoluble and Soluble Dietary Fiber in Food-Enzymatic-Gravimetric Method, MES-TRIS Buffer. (1995). Official Methods of Analysis, 16th ed. AOAC International, Gaithersburg, MD. Link to book
17. Lee, S. C. & Prosky, L. (1995).  International survey on dietary fiber definition, analysis, and reference materials.  J. AOAC Int., 78(1), 22-36. Link to article
18. Cho, S. S. & Prosky, L. (1999).  Summary of AOAC survey on complex carbohydrates/dietary fiber. “Complex Carbohydrates/Dietary Fiber”, (S. S. Cho, L. Prosky, and M. Dreher, Eds.), Marcel Dekker, New York, NY. Link to article
19. Gordon D. T. & Okuma K. (2002).  Determination of Total Dietary Fiber in Selected Foods Containing Resistant Maltodextrin by Enzymatic-Gravimetric Method and Liquid Chromatography: Collaborative Study.  J. AOAC Int., (85)2, 435-444. Link to article
20. Champ, M. (1992).  Determination of resistant starch in foods and food products: interlaboratory study.  Eur. J. Clin. Nutr., 46(Suppl. 2), S51-S62. Link to article
21. Berry, C. S. (1986).  Resistant starch: Formation and measurement of starch that survives exhaustive digestion with amylolytic enzymes during the determination of dietary fibre.  J. Cereal Sci., 4(4), 301-314. Link to article
22. Englyst, H., Wiggins, H.S. & Cummings, J. H. (1982).  Determination of the non-starch polysaccharides in plant foods by gas-liquid chromatography of constituent sugars as alditol acetates.  Analyst, 107, 307-318. Link to article
23. Muir, J. G. & O’Dea K. (1992).  Measurement of resistant starch: factors affecting the amount of starch escaping digestion in vitro.  Am. J. Clin. Nutr., 56, 123-127. Link to article
24. McCleary, B. V. & Monaghan, D. (2002).  Measurement of resistant starch.  J. AOAC Int., 85(3), 665-75. Link to article
25. McCleary, B. V., McNally, M. & Rossiter, P. (2002).  Measurement of resistant starch by enzymatic digestion in starch and selected plant materials: Collaborative study.  J. AOAC Int., 85, 1103-1111. Link to article
26. McCleary, B. V. (2007).  An integrated procedure for the measurement of total dietary fibre (including resistant starch), non-digestible oligosaccharides and available carbohydrates.  Anal. Bioanal. Chem., 389(1), 291-308. Link to article
27. McCleary, B. V., DeVries, J. W., Rader, J. I., Cohen, G., Prosky, L., Mugford, D. C. & Okuma, K. (2010).  Determination of total dietary fiber (CODEX definition) by enzymatic-gravimetric method and liquid chromatography: Collaborative study.  J. AOAC Int., 93(1), 221-233. Link to article
28. McCleary, B. V., DeVries, J. W., Rader, J. I., Cohen, G., Prosky, L., Mugford, D. C. & Okuma, K. (2012).  Determination of insoluble, soluble, and total dietary fiber (CODEX definition) by enzymatic-gravimetric method and liquid chromatography: Collaborative study.  J. AOAC Int., 95(3), 824-844. Link to article