Determination of β-Galactooligosaccharides (GOS) in Infant Formula: Collaborative Study, Final Action 2021.01

Background We previously published a method for the determination of β-Galactooligosaccharides (GOS) in Infant Formula and Adult Nutritionals which is currently First Action AOAC Method 2021.01. In this study, reproducibility data were collected to support the promotion of the method to Final Action. Method A collaborative study was organized, to which 14 laboratories from eight different countries participated. Initially, laboratories were requested to analyze two practice samples and request guidance from the study director in case of issues. Successful laboratories proceeded to analyze seven samples (six infant formula and one adult nutritional) received as blind duplicates. Results Thirteen laboratories reported acceptable results for practice sample 1. Practice sample 2 could only be delivered to eight of the laboratories due to restrictions at customs. The 13 laboratories successfully analyzing practice sample 1 were requested to continue with the analysis of the MLT samples. Laboratory 14 was unable to solve some technical difficulties, so their data could not be used. Out of the seven samples tested, results for six infant formula met the requirements of the AOAC SMPR 2014.003, with RSDr ranging from 1.4 to 4.7% and RSDR ranging from 8.1 to 11.6%. The adult nutritional sample returned results outside the range of SPMR, having repeatability (RSDr) of 9.9%, higher than the SMPR target of ≤ 6%, and reproducibility (RSDR) of 12.1%, just above the SMPR target of ≤ 12%.