Measuring Total Dietary Fiber of Resistant-Starch Products Using Different Test Kits
A. Evans. Tate and Lyle Research, Decatur, IL. Cereal Foods World 52(3):126-128.
AACC International methods 32-07 (AOAC 991.43) and 32-05 (AOAC 985.29) may be used to measure the total dietary fiber (TDF) in food systems and in food ingredients such as resistant starch (RS). Two enzyme preparation kits for the analysis of TDF by AACC International methods 32-07 and 32-05 were evaluated. A significant difference between the two enzyme preparations was found when used on RS samples. The enzymes offered by one kit produce much lower percent TDF in RS samples than the other enzymes. Based on the enzyme activities and volumes reported, alpha-amylase from one kit is much more active than the other kitís. While this difference of alpha-amylase activity does not cause a problem for traditional nonstarch fibers, the use of the more active kitís alpha-amylase can lead to significant underestimation of the TDF content for RS samples. The buffer system used in AACC International 32-07 and 32-05 seemed to influence the activity of these enzymes differently when used at equal activity levels. The variation in enzyme activity between manufacturers and the potential difference between the buffer systems used in AACC International 32-07 and 32-05 need to be investigated further.