Fiber Testing Evolved: The Next Generation of AOAC Fiber Methods

What’s the latest on dietary fiber methods?

More laboratories are implementing the Rapid Integrated Dietary Fiber Methods - AOAC Official Methods 2017.16 and 2022.01. The AOAC 2017.16 method measures the insoluble fiber fraction (IDF) and soluble fiber fraction that precipitates in 78% ethanol (SDFP) together, and separately measures the soluble dietary fiber not precipitated in 78% ethanol (SDFS) by HPLC. The results from each fraction are summed to provide the total dietary fiber (TDF). The AOAC 2022.01 method provides the additional ability to measure the IDF and SDFP fractions separately. These methods are updates to the AOAC Official Methods 2009.01 and 2011.25.

Why the updates and what are the benefits?

These updates were to provide solutions to some of the observations found in the AOAC 2009.01 and 2011.25 methods to provide optimal alignment with the Codex Alimentarious Commission (CAC) definition of dietary fiber.  

The following is a list of improvements for AOAC 2017.16 and 2022.01: 

• Incubation with pancreatic α-amylase and amyloglucosidase was changed from 16 hours to 4 hours –  
  
  • More physiologically relevant residence time within the small intestine. 
  • Reduces the excessive hydrolysis of phosphate cross-linked starch (RS4). 
• Enzyme levels were increased – 
  
  • Complete hydrolysis of resistant oligosaccharides formed during the enzymatic incubation with high starch products. 
  • More closely matches ileostomy studies of resistant starch digestion. 
• More accurate hydrolysis of isomaltooligosaccharides (IMO). 
• Analytical column change – 
  
  • Provide a more accurate quantitation of fructooligosaccharides (FOS) for inclusion of inulotriose (F3).

How is regulatory or the scientific community responding?

The AOAC methods 2017.16 and AOAC 2022.01 have replaced AOAC 2009.01 and AOAC 2011.25 as Codex Commission Method of Analysis and Sampling (CCMAS) CODEX Type 1 methods, respectively.  Additionally, the Dietary Fiber & Other Carbohydrates Program through AOAC currently has a working group with representatives from a wide range of demographics designing a guidance document for publication soon on dietary fiber testing, and within this document is directing the use of these methods in replacement of the AOAC 2009.01 and 2011.25 methods. Based on these events, the consensus from CCMAS and AOAC is to dissolve these previous methods and adopt the updated versions for dietary fiber testing to support nutritional labeling.

How will I know if this change will impact my product?

When evaluating fiber testing approaches, it’s important to review how results differ across sample matrices tested by both the new and previous methods. Comparison data will be available to help you understand these differences and make informed decisions. 

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