Shellfish are deeply loved by people because of their tender meat, delicious taste and rich nutrients. However, shellfish are filter feeders, thus have strong ability of filter-feeding, with continuous enrichment of microorganisms in the feeding water. Therefore, shellfish have become the main carrier for the spread of foodborne pathogenic microorganisms. Vibrio parahaemolyticus is a kind of halobacteria, and is one of common foodborne pathogenic microorganisms in economic shellfish. Therefore, people attach much attention to the safety condition of shellfish.
Shanghai is an imported-type megapolis. Shellfish may be contaminated with foodborne pathogenic microorganisms during the storage and transportation process from farm to table. Therefore, people attach much attention to the safety condition of economic shellfish for sales in Shanghai. For this purpose, the Food Safety and Microbiological Research Team from Shanghai Jiaotong University conducted a survey on contamination of vibrio parahaemolyticus in main economic shellfish for Sale in Shanghai from 2012 to 2015 under the leadership of Professor Shi Xianming, Chinese director of Sino-US Food Safety Center. In such study, 404 economic shellfish samples (mainly include: oysters, clams, razor clams, etc.) were collected randomly, it was found that despite the contamination rate of vibrio parahaemolyticus was 32.67% (132/404), the positive rate of pathogenic vibrio parahaemolyticus was only 2.97% (12/404), which was equivalent to the level in developed countries; the positive rate of pathogenic bacteria showed a downward trend year by year. In conclusion, such economic shellfish are in good condition.
The study also conducted evaluation on the contamination level of vibrio parahaemolyticus in different tissues of oysters. It was found that the gill tissue and digestive gland of oysters had a higher level of pathogenic bacteria content, thus they can be used as the target tissues for detection of pathogenic bacteria in shellfish, which provides data support for update of national standard detecting method of vibrio parahaemolyticus (GB/T 4789.7-2013). In addition, the research results showed that the contamination level of vibrio parahaemolyticus in shellfish was positively related with seasonal changes. The pathogenic vibrio parahaemolyticus were from shellfish samples in summer, therefore, it is suggested to eat shellfish fully cooked in summer to avoid food poisoning.
This project was invested by National Project 863 (2012AA101601) and Project of National Natural Science Foundation of China (31000063). Relative research achievements of this project have been published in Journal of Chinese Institute of Food Science and Technology and Food Control (SCI-B) recently.