The uncertainty in the determination of aerobic plate count in raw milk was evaluated and the feasibility of the uncertainty for judging the conformity of the test results. According to the two Chinese standards National Food Safety Standard Food Microbiological Examination: Aerobic Plate Count (GB 4789.2-2016) and Evaluation and Expression of Uncertainty in Measurement (JJF 1059.1-2012), uncertainty evaluation was carried out on 10 batches of raw milk. The extended uncertainty for the 10 batches was 0.031 0-0.033 6 (lg(CFU/mL)). The established method could be used for uncertainty assessment of aerobic plate count detection in raw milk, and the obtained uncertainty could be used for assessing the quality of raw milk.

The protocooperation mechanisms of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilusis is of great importance to the fermentation of milk, especially to bacterial adaptability to in acid environment. This paper discusses the symbiosismechanisms of the two strains from the following perspectives: two-component signal transduction systems, horizontal gene transfer, protein metabolism, nucleotide base metabolism, oxidative stress and carbon source metabolism, aiming to provide valuable references for further investigations on improving the quality of fermented milk products.