The Smoke and Mirrors of the R Rule

From the Desk of Stu Meltzer

Late summer at Standish Shore oyster farm in Duxbury, MA

Late summer at Standish Shore oyster farm in Duxbury, MA

The 'R' Rule

Everyone in the seafood business should be familiar with this concept, the age old guideline to only eat oysters in months that contain the letter R.  Most of us are aware that this recommendation exists because bacteria that can be harmful to humans (such as vibrio) has the greater likelihood to flourish under warmer weather (and water) conditions.  Today, oyster growers have the necessary equipment and technology to bring the temperature of harvested product down quickly to inhibit any bacteria growth. Further, supply chain partners (such as yourselves) maintain rigorous processes to keep oysters at the appropriate temperatures to mitigate incidence of bacteria growth.  In sum, harmful bacteria as a reason to avoid oysters in warmer months no longer applies.

The other motivation for this concept is the fact that oysters spawn during the summer months.  The graph below illustrates the shell volume for oysters over the course of a year.  You will notice that oysters begin to feed and put on weight starting in January. During early spring, the oysters begin eating more and developing egg and sperm in advance of their spawn.  This explains the uptick in weight in early spring represented on the graph.  After the spawn, the shell volume plummets, creating a less than desirable eating experience. In the fall, the oysters start putting on weight again to carry them through the winter. 

Cassostrea virginica Shell Volume/Density

Courtesy of Roger Williams University

Courtesy of Roger Williams University

Although people, particularly on the East Coast, associate summer and the beach with oysters, you can see that summer may be the worst time to be eating them from a product quality perspective. To remedy this situation, some smart and determined oyster loving scientists figured out how to develop an oyster that does not spawn, known as a triploid.

The underside of a triploid oyster in the middle of summer shows a plump and firm belly without signs of spawn.

The underside of a triploid oyster in the middle of summer shows a plump and firm belly without signs of spawn.

Triploids

A diploid oyster just after spawn looking weak and in desperate need of a cheeseburger

A diploid oyster just after spawn looking weak and in desperate need of a cheeseburger

Like humans, oysters are naturally diploid organisms.  This means that oysters have two sets of chromosomes.  Triploids are organisms with three sets of chromosomes. This uneven number of chromosomes mostly renders these organisms infertile.  As you could gather from the previous discussion, an oyster that does not reproduce would theoretically maintain their quality during the time of greatest market demand. 

 

 

 

 

This is the advantage of the Triploid oyster. That said, the adoption of Triploid oysters by growers is not as widespread as you might expect.  Triploid oyster seed can be a bit more expensive than their diploid counterparts and, depending on what climate the grower is in, spawning may have a marginal impact on product quality, but for the regions where spawning can greatly impact product quality, triploids can be an undeniable asset.    

As you can see above, the triploid oyster is plump and ready for slurping, even in the warmest months, but it may be as good as it gets throughout the season. The diploid oyster shown just after spawn is still edible, but there is not much to the meat and the flavor falls flat. Fast forward a few weeks, and this oyster will take on a whole new personality with a dynamic brine and texture that is worlds apart from the picture presented.

 

In Summary

Natural oyster physiology should still be considered when choosing when to promote oysters. Early spring can be a good time, but if that is timed incorrectly, your customers can end up with spawny oysters.  We strongly recommend you run oyster promotions in the fall.  The oysters are fattest and supply is greatest. Sadly, summer will be over before we know it.  Let’s start talking about running a fall oyster special with you now!  

 

Recipe: Grilled Large Oysters with Corn Cream

serve on top of coarse salt for a flawless and wobble-free presentation

serve on top of coarse salt for a flawless and wobble-free presentation

by Bekah Angoff

12 large oysters, shucked and in the shell (shells should be thick and about 4.5inches in length) – we used xl Pemaquids for this recipe

2T unsalted butter
2 ears fresh corn – cobs and kernels separated
½ c. minced red onions
2 cloves garlic minced
6 sprigs fresh thyme
½ c white wine
3c. heavy cream
3T finely shredded parmesan cheese
sliced cherry tomatoes
salt and pepper
Chopped mixed herbs for garnish (chives, parsley, etc)
 

In a heavy bottomed sauce pot, sweat the onions and garlic in the butter over medium heat, being careful not to brown anything. When the onions are translucent, add the corn kernels and 3 sprigs of thyme to warm through. Add the wine and reduce the liquid by half.

Turn down the heat to low and add in the cream and the corn cobs, stirring gently. Slowly, reduce the mixture by a half, making sure to stir occasionally so that a skin down not form on the top and the cream does not scald on the bottom.

Support the bill of the oysters with a row of foil to prevent any spillage

Support the bill of the oysters with a row of foil to prevent any spillage

Once the cream is reduced, take the pot off the heat and let it cool down to room temperature. Scrape the cobbs into the liquid and then discard the cobbs (the starch extracted from the cobs will help the cream thicken). Season the cream with salt and pepper (remembering they it will be on top of briny oysters) and add the remaining sprigs of thyme and the parmesan. Transfer everything to a container and refrigerate overnight.

Preheat the grill to medium high and set up foil barriers to help the oysters stay in place (see picture). Top each large shucked oyster with about a tablespoon of the corn cream and three small slices of tomato. Cook each oyster until the corn cream is bubbling and the edges start to turn golden brown.

Top with chopped herbs and serve right away!