Cereals & Grains Association
Log In

An integrated procedure for the measurement of total dietary fiber—Challenges and updates
B. MCCLEARY (1). (1) Megazyme International Ireland Ltd., Bray, Ireland

In 2007, we published an integrated method for the measurement of total dietary fiber, which allowed accurate measurement of resistant starch and low molecular weight oligosaccharides as well as the high molecular weight dietary fiber traditionally measured. This method has been successfully subjected to interlaboratory evaluation through AOAC International and AACC International in 2009 and 2011. However, in applying this method to a broad range of samples, a need for minor modification to allow correct measurement of specific components has been identified. Particular attention has been directed to the overestimation of low molecular weight dietary fiber in high starch containing materials through incomplete hydrolysis of certain maltodextrins, and to the underestimation of partially hydrolysed inulin, specifically the trisaccharide, fructosyl-β(2-1)-fructosyl-β(2-1)-fructose. The reasons for differences in the determined dietary fiber values of phosphate cross-linked starches has also been studied in detail. Fructo-oligosaccharides can be specifically measured after hydrolysis to fructose and glucose using a mixture of exo-inulinase and endo-inulinase. Measurement of trace amounts of these oligosaccharides in materials containing high levels of other sugars such as in baby formulations or in cereal grains has been complicated by the requirement for ultra-pure enzymes. It is difficult to produce enzymes of the required purity by traditional chromatographic procedures. This problem has now been resolved using recombinant technology and a eukaryotic expression system.

View Presentation