Coast oyster processors have taken the lead in developing new technologies
to ensure safer alternatives to traditional raw oysters for at-risk
consumers. These processes allow the oyster to be consumed raw, but
with added safety features that reduce Vibrio vulnificus to non-detectable
oyster consumers can now eat raw oysters with reduced risk of Vibrio
Three post-harvest treatment processes currently exist on a commercial
scale(1): individual quick-freezing (IQF),
low heat pasteurization or heat-cool pasteurization (HCP), and high-hydrostatic
pressure (HPP). Although these technologies currently account for less
than 10% of all 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 oyster
Each process has unique advantages and characteristics which provide
greater convenience for all customers, while at the same time reducing
risk for at-risk
- Freezing oysters to extend shelf life was first applied in 1989; and
presently, there are several facilities using this technique with oysters.
The process has also become popularized on a worldwide scale with Australia,
Canada, New Zealand and the United States leading the pack. IQF processing
of oysters is presently being applied by companies in California, Florida,
Louisana and Texas. It has the biggest market share of the post-harvest
processed raw oyster market. Many prefer the IQF oysters because of
quality, taste, and convenience. The IQF “fresh frozen”
technology keeps all of the flavor and appeal of non-processed oysters
– the major selling point of the process. IQF oysters are typically
sold with the top shell removed.
HCP - Heat-cool pasteurization of oysters was initially
developed in 1995 by a private firm in Louisiana. This process involves
submerging the raw product into warm water followed by immediate cold
water immersion. Shellstock is washed, graded, sorted, banded and treated.
Banded oysters are placed on a large tray and then a hoist lifts and
places them in warm water at 127oF for 24 minutes. The trays are lifted
out and placed in 40oF water for 15 minutes. The trays of cooled, banded
oysters are stacked on carts to drip dry ready for boxing and storage.
– High pressurization processing was pioneered in the meat and
juice industries; however, its application to oysters was initiated
in 1999 in Houma, LA. This type of processing starts with cleaning,
washing, sorting and grading oysters. They are then banded and containerized
(placed in a stainless steel cylinder) in preparation for the high-hydrostatic
pressure of 45,000 pounds per square inch. After pressurization, the
oysters are then shucked for half shell or packaged as banded oysters.