Not according to the standards.

Rationale: The requirement to reproduce D-values to within the +/- 20% is a manufacturers specification when reproducing ones own test results. Users have erroneously adopted this guideline.

ANSI/AAMI/ISO 11138-1:2006, which replaces ANSI/AAMI ST59:1999 and EN 866:1999, states the following:

6.4.3. The D-value shall be within +/- 20% of the manufacturers stated value when determined by the manufacturer during the stated shelf life using the method specified by the manufacturer.

A study conducted in 1990 by Gordon Oxborrow¹ of the FDA laboratory in Minnesota concluded that the +/- 20% specification is not appropriate for third party testing and is only likely to be routinely achieved when the manufacturer is reproducing their own data. Shintani² et al. 2000, has also stated that if there are significant differences in spore recovery (D-values) with different lots and manufacturers of soybean casein digest media. If end users insist upon testing to the +/- 20% specification, they are likely to routinely reject good product based on misinterpretation of the standards.

¹Medical Device & Diagnostic Industry, May 1990, p. 78-83, G. S. Oxborrow, C. W. Twhoy and C. A. Demitrius

²PDA Journal of Pharmaceutical Science & Technology, Vol. 54, No. 1, January/February 2000, p. 6-12, H. Shintani, K. Sasaki, Y. Kajiwara, J. Itoh, M. Takahashi, and M. Kokubo