RI-ERP-FINALACTION-Recommendations

AOAC RESEARCH INSTITUTE AOAC OFFICIAL METHODS OF ANALYSIS (OMA)

OMAMAN-13: Determination Of Dietary Starch In Animal Feeds And Pet Food By An Enzymatic- Colorimetric Method Collaborative Study* Study Director: Mary Beth Hall, U. S. Department of Agriculture – Agricultural Research Service, U.S. Dairy Forage Research Center, 1925 Linden Drive, Madison, WI 53706, USA ER 5 Same temperature for both enzymatic procedures, allowing better efficiency. Changed to quadratic curve due to the slight non-linearity of the standards. ER 6 It would be interesting to understand why leaving the sample (taking a break) after dilution of fully digested samples has an impact on recovery (line 699, p31) ER 7 good ER 8 n/a ER 3 Range studied was 1.00% - 69.6%. Corn starch was used as a spiking agent which suggests this material can be tested directly on this material (89% dietary starch) as long as enzymes are keep in sufficient excess/ ER 4 See method collaborative study report. ER 5 ~1% to 100% ER 6 about 1 (lowest amount in samples tested in MLT) - 100% starch (considering corn starch used as control) ER 7 good ER 8 Acceptable Analytical Range ER 1 ER 2 1-100% 0-100 mg starch in the assay ER 6 This has been estimated as 0.2% dietary starch by using reagent blanks. The approach seems reasonable, although one may expect the practical LoQ to be higher when applied to samples (and is probably not independent of the free glucose content of a sample) ER 7 good ER 8 Acceptable This does not appear to have been extensively tested. Pure starch products have been assayed and the recoveries are greater than 95%, Dextrins appear to be more problematic, but this does not seem to have been discussed. ER 7 good AOAC Research Institute ERP Use Only Accuracy/Recovery ER 1 ER 2 ER 3 ER 4 99.3 pure corn starch, 90@ control corn starch. 89.9% +/- 3.7% 993.8% wi+/- 0.8% is excellent See method collaborative study report. ER 5 Pure corn starch: 99.3% ± 0.8% (Theoretical = 100%) Corn Starch: 89.9% ± 3.7% (Estimated = 89.4) ER 6 LOQ ER 1 ER 2 ER 3 ER 4 ER 5 Approx. 0.3% (probably a little larger)- definitely less than 1% 0.9% of starch sample weight basis 0.3%. Acceptable limit. See method collaborative study report. 0.3%