Gulf Coast oyster processors have taken the lead in developing new technologies to ensure alternatives to traditional raw oysters for certain at risk consumers. Through three basic methods of post-harvest treatment, processors throughout the Gulf Coast are providing greater choices and wider availability of treated oyster products with non-detectable levels of Vibrio vulnificus: a naturally occurring bacteria which may adversely impact consumers with certain underlying health conditions.

While different technologies are employed, each post-harvest treatment (PHT) process is designed to allow at-risk consumers to enjoy uncooked oysters with an added margin of safety and greater peace of mind. Not insignificantly, these processes were developed and successfully marketed by private entrepreneurs in response to consumer demand, and without a government mandate or directive.

Existing post-harvest treatment processes take variations of three forms: individual quick freezing (IQF), low heat pasteurization, and hydrostatic high pressure (HPP)treatment, Although these technologies currently account for less than 10% of all domestic raw oyster sales in the United States, on-going marketing and educational efforts geared toward the at-risk consumer are expanding acceptance and knowledge regarding these PHT oyster products. Such efforts will clearly open the market for these products, thereby creating less risk for the at risk consumers of raw-like oysters in the future. Specific processes and other facts regarding each are discussed below.

Individual Quick Freezing (IQF)

IQF technology has been applied to oysters since 1989. Freezing is done either cryogenically or using conventional blast freezing. IQF oysters are typically sold with the top shell removed.

The IQF process has been shown to eliminate or reduce Vibrio vulnificus to non-detectable levels.

Low Heat Pasteurization

Low heat pasteurization was developed by a private firm in Louisiana in cooperation with Louisiana State University. The process has been in use since 1995. Low heat pasteurization involves a simple warm and cold water temperature treatment of in-shell oysters to reduce Vibrio vulnificus to non-detectable levels.

High Pressure Processing

A Houma Louisiana-based company is currently producing oysters treated with the newest PHT technology (began in 1999) which involves subjecting in-shell oysters to a hydrostatic-high pressure of up to 45,000 psi. Vibrio vulnificus is reduced to non-detectable levels and oysters are automatically separated from their shell during this process. Pressure treated oysters are placed in a specially developed pressure chamber capable of generating high levels of hydrostatic pressure.

Each process has unique advantages and characteristics which provide greater convenience for all customers as well as creating less risk for those consumers who are at risk of illness from Vibrio vulnificus. Cumulatively these processes will help the Gulf Oyster industry continue to provide all customers with the ability to choose oyster products which meet their individual health concerns. This in turn will lead to lower risk of Vibrio vulnificus infections nationwide.