Su 2012-2013 Research Update
Seafood Microbiology and Safety
Yi-Cheng Su, Associate Professor, Coastal Oregon Marine Experiment Station and Department of Food Science & Technology
Research on seafood microbiology and safety at the Seafood Research and Education Center in Astoria has been focused on development of innovative post-harvest processes for reducing Vibrio parahaemolyticus contamination in raw oysters for safe consumption.
Vibrio parahaemolyticus is a foodborne pathogen recognized as the leading cause of gastroenteritis associated with seafood consumption in the U.S. This bacterium occurs naturally in the marine environments and is frequently isolated from seafoods, particularly oysters. The U.S. Center for Disease Control and Prevention (CDC) estimates that Vibrio parahaemolyticus is responsible for 45,000 cases of foodborne infections each year in the U.S.
Studies were conducted to investigate effects of water temperature on depuration, a controlled purification process by holding shellfish in clean seawater to allow reduction of microbial contaminants from shellfish, using refrigerated seawater (5-12.5°C) and discovered that the process reduced Vibrio parahaemolyticus contamination in oysters by >99.9% (>3.0 log MPN/g reductions) after 4-5 days of processing. Additional studies investigating effects of water salinity (10-30 ppt), oyster types (diploid and triploid) and oyster sizes on depuration for reducing V. parahaemolyticus contamination in Pacific oysters (Crassostrea gigas) revealed that types and sizes of oysters had no impact on the efficacy of depuration for reducing V. parahaemolyticus in oysters. However, the efficacy of depuration in reducing V. parahaemolyticus in oysters was influenced by water salinity. Such a factor needs to be considered when developing a depuration process for eliminating V. parahaemolyticus in oysters.
Dr. Su was invited to visit Zhejiang Ocean University in China in December 2012 to give a series of lectures on Seafood Safety, Rapid Methods for Pathogen Detection and HACCP Development to graduate students. He also gave seminars on a number of topics related to seafood safety to graduate students of Shanghai Ocean University, China Agricultural University, Jinan University and South China Agricultural University in China in March 2013. In April 2013, Dr. Su was invited to visit National Pingtung University of Science and Technology and National Kaohsiung Marine University in Taiwan to explore collaboration in seafood science research.
Dr. Su continued to serve on the Editorial Boards of Journal of Aquatic Food Product Technology, Journal of Food Protection, and Journal of Food Safety and as an ad-hoc reviewer of several professional journals. He gave lectures on Microbiology and Sanitation and taught Microbiology Laboratory at the 21th OSU Surimi School in May 2013. He also worked with the Oregon Department of Agriculture to teach Seafood HACCP course to the seafood industries in Salem in April 2013.