Analysis and evaluation of microbial contamination of retail ready-to-eat foods in Shanghai from 2016 to 2020

Abstract

ObjectiveTo verify the potential food safety hazards and provide a scientific basis for risk assessment， risk management and food safety standards formulation of ready-to-eat （RTE） food in Shanghai.MethodsFrom 2016 to 2020， 10 521 food samples of 20 kinds of RTE foods were collected in Shanghai. A series of qualitative or quantitative detection of two hygienic indicator bacteria and six pathogenic bacteria， including the aerobic plate count （APC）， Escherichia coli （E.coli） count， Vibrio parahaemolyticus （V. parahaemolyticus）， Staphylococcus aureus， Diarrheagenic E. coli， Salmonella spp.， Bacillus cereus （B. cereus）， and Listeria monocytogenes （L. monocytogenes） were conducted. and the correlation between them was analyzed.ResultsThe highest average APC count of cold rice noodle products， salad and Chinese salad were （5.13±1.43）lgCFU/g， （4.56±1.13）lgCFU/g， （4.26±1.75）lgCFU/g， and the E. coli count were （1.20±1.00）lgCFU/g， （1.47±1.41）lgCFU/g and （1.18±1.06）lgCFU/g. The positive rates of L. monocytogenes in cold pot skewers， salad， Chinese salad and cooked meat products were relatively high （6.27%， 3.36%， 2.71% and 2.69%， respectively）. V. parahaemolyticus was only detected in three categories， including 3.65% of raw animal aquatic products， 2.58% of Chinese salad and 0.42% of cooked meat products. The positive rate of B. cereus in rice noodle products was 7.51%， which was significant higher than sushi， whose rate was 0.53% （P<0.05）. The APC level was positively correlated with the E. coli count （P<0.001） and the positive rate of foodborne pathogens （P<0.05）.ConclusionRaw food， salad， sandwich and other RTE foods without further heating had the highest level of hygiene indicator bacteria and foodborne pathogens， which indicated a high risk of foodborne disease which should be the focus of prevention. There was a positive correlation between the average APC level and the positive rate of foodborne pathogens in solid RTE foods.

Keywords

• ready-to-eat food
• microbial contamination
• foodborne pathogens
• risk monitoring
• food safety