An Interlaboratory Method Comparison Study of GB 4789.40-2016 and ISO 22964:2017 Detection of Cronobacter spp. in Powdered Infant Formula

It is documented that Cronobacter spp.(formely named as Enterobacter sakazakii ) can live in the powdered infant formula (PIF) for a long period, and special concerns have been raised about the safety of powdered infant formula (PIF) contaminated by Cronobacter spp with the globalization of the food supply. A method comparison study between the Chinese standard method GB 4789.40–2016 (reference method) and the European standard method EN ISO 22964:2017 (alternative method) for detecting Cronobacter spp. in PIF was performed according to ISO 16140-2 2016. A total of 576 blind-coded test portions of the product spiked with the test strain at 3 different contamination levels were analyzed by 12 participating laboratories. The results showed that the sensitivity of GB 4789.40–2016 was 80% and 81.16% at the low and high contamination levels, respectively, while those of ISO 22964:2017 were 90% and 97.10%, respectively. The Relative Levels of Detection (RLODs) were below the acceptance limit (AL) regardless of the contamination level. The results were also analyzed using the probability of detection (POD) model proposed in the AOAC guidelines, and showed no statistically significant difference between the alternative and reference methods. The ISO 22964:2017 method was considered equivalent to the GB 4789.40–2016 method for the detection of C. sakazakii in PIF.