High pressure treated oysters taste better, say consumers

Sydney Rock oyster (left) compared with a Pacific oyster.

Oysters treated with high pressure water look and taste better, according to consumers who participated in a NSW Department of Primary Industries (DPI) research project.

The study sought to find out whether oyster consumers could detect the difference between triploid and diploid Pacific oysters and whether the taste was affected by high pressure (HP) water treatment.

Triploid oysters have three chromosomes and are better suited than diploid (two chromosome) oysters for farming in areas such as Port Stephens. They also grow more quickly and are meatier.

Pacific oysters though have a shorter shelf life than Sydney rock oysters: hence the search for new treatments which would enable them to be stored longer under refrigeration.

According to DPI Principal Research Scientist, Dr John Nell, “high pressure water could prolong the shelf life as well as deactivate micro-organisms”.

In trials conducted by Food Science Australia, 61 consumers were asked to evaluate triploid and diploid oysters which had either been shucked immediately prior to tasting, or given HP treatment four days beforehand.

Each of the HP treated oysters was secured with a rubber band and shucked in the process of being sprayed.

Dr Nell said the consumers found no difference in taste between the triploid and diploid oysters.

“This is good news for oyster farmers because triploidy in NSW results in faster growth and better meat condition over late spring and early autumn, when diploids spawn.”

The consumers tested also found that the HP treatment had no negative effect on eating quality.

“In fact, HP actually improved the appearance of both triploid and diploid oysters and reduced the intensity of perceived saltiness in oysters”, Dr Nell said.

“Consumers found this appealing. Their assessment of the ideal salt intensity was similar to that perceived in the HP treated oysters.”

The study was reported in the December 2006 issue of the international Journal of Shellfish Research.

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