315 / 328
ER 3
Spectrophotometric measurement does work well and is easy, quick, and reliable. Quantitative of
sugars by HPLC is also simple (a bit more expensive though) but will allow tracking of sucrose to assure
its digestion did not occur. The method's steps do prevent sucrose digestion by relying on high-purity
enzymes. Since these enzymes are more expensive, laboratories using lower cost enzymes would be at
risk of reporting less accurate, higher values.
ER 4
Lack of sophisticated instrumentation will be unappealing to those inclined to high level tech methods.
ER 5
Quadratic fit may be difficult for some users to use, and automation of the whole quantitation process
is somewhat difficult to achieve. Scaling up is somewhat limited because of the need to measure
absorbency within 30 min of GOPOD reaction. High content of anti-oxidant will prevent accurate
determination of glucose, forcing other glucose detection methods into consideration.
ER 6
- potential interference of substances with anti-oxidant activity (if this is unknown it needs to be
assessed somehow, or an alternative glucose assay should be used) - although it is mentioned that
glucose assays other than GOPOD can be used, it does not appear to have been tested or validated. - it
is mentioned that leaving the sample (taking a break) after dilution of fully digested samples has an
impact on recovery - but why should that be the case?
ER 7
none
ER 8
This is a good method, but would appear not to be an improvement over AOAC
Supporting Data Comments
ER 1 Impressive data package
ER 2
15 labs. collaboratively studied the method and analyzed 10 homogenous test materials (animal feeds
and pet foods) using the described method for dietary starch (ranging starch contents of 1-70%). The
average within lab. Repeatability as sr for % Dietary starch was 0.49 with a range of 0.03 to 1.56, and
among –laboratory repeatability of standard deviation sR averaged 0.96 with a range of 0.09 to 2.69.
HORRAT averaged 2.0 for all test samples and 1.9 for samples containing dietary starch more than 2%.
ER 3
Excellent study
ER 4
Excellent data package. Well done study.
ER 5
Well-organized summary tables about statistics of all matrix results Good study on the glucose
standard responses across different batches
ER 6
This looks to be a straight forward assay which did not appear to be problematic for most of the labs
involved in the MLT. The authors have mentioned that alternative assays for glucose could be used
instead of GOPOD (and may be essential for samples with high anti-oxidant contents). It would be
interesting to know if this has been tested in any of the labs because although it is mentioned it does
not appear to have been verified.
ER 7
good
ER 8
Method should be accepted with some changes to text
Method Optimization
ER 1 Done
ER 2
The method has been optimized for its efficiency and better recovery of starch.
ER 3
Keep as written (see comment in Cons/Weaknesses for optional digestion)
ER 4
No further work needed.
ERP PROFILE SUMMARIES
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