Scientist study the potential of marine material typically tossed overboard
By KELLY KITTEL/ecoRI News contributor
When you think about sea scallops you likely picture them either pan-seared or fried. But researchers at the University of Rhode Island may be changing the way we think about scallops, with new discoveries about their beneficial uses in medicines or as a tasty new ingredient in fish food.
Chong Lee, URI professor emeritus and research in nutrition and food sciences, said the value of sea scallops regionally is significant. “The port of New Bedford is not as large as the one in Alaska, but in terms of dollar value, it’s the highest ranking port in the U.S. because of scallops,” he said.
This is especially interesting as more than half of the scallop itself, once caught, never even reaches the dock. The part of the scallop people love to eat is the large adductor muscle that grows up to 2 inches in diameter. Fishermen typically shuck their catch at sea, discarding the remaining shell, roe and viscera. Sea scallop management regulation limits the commercial landings by weight and doesn’t currently differentiate the landing of viscera, which would more than double the weight landed.
Enter Lee and his team of URI researchers. They have been looking at ways to turn byproducts of local fisheries into marketable commodities. Working with funding from the Commercial Fisheries Research Foundation and Rhode Island Sea Grant, Lee has spent the past two years studying scallop viscera to find a way to fully develop its commercial potential for such uses as an ingredient in high-value, specialty aquafeed, and for its nutraceutical ingredients.
“We’ve been working on (studying the viscera of) squid and other fish species, so we have all the know-how and technology to look at scallop viscera,” Lee said.
The term “nutraceutical” is used to describe a food or food product that provides health benefits through improved disease prevention above and beyond simple nutrition, such as the benefits of omega-3 fatty acids in fish oil in lowering the risk of cardiovascular disease. Lee and his team have been investigating the nutraceutical properties of scallop viscera hydrolysate (SVH) as well as that of squid. Hydrolysate is produced by breaking down the scallop viscera proteins using the animal’s own internal enzymes.
They found that SVH may aid lipid, or fat, digestion, which is significant since there is a sizable human population that has problems digesting fats. Their research also found properties of both squid and scallop viscera that may help lower blood pressure. Lee’s team also examined the concentrations of omega-3 fatty acids EPA and DHA in the SVH. Levels of both were found to be higher than those in fish, including salmon, and comparable to those in squid hydrolysate.
While the viscera showed promise in reducing hypertension, Lee conceded that it may not be as effective as products already on the market. “I want to look at it further to validate how important it is,” he said, noting that the team’s study of lipase activity — the fat-digesting enzyme— in SVH is likely “the first time people have looked at lipase in terms of marine resources.”
A better fish food
Traditionally, fish meal has been used as a primary source of protein for farm-raised fish. However, it is not sustainable, and efforts are being made to find new sources of proteins besides soybean meal. Lee and his team assessed SVH for its attractiveness to fish as a flavor enhancer as well as its capacity for stimulating growth. They compared the scallop viscera with that of squid, as well as with soybean and fish meal in a variety of combinations.
They conducted feeding trials on summer flounder and European sea bass that revealed that SVH performed the best in terms of weight gain and feed consumption. They believe this is due to its properties as a feeding attractant or flavoring that stimulates feeding behavior.
In other words, scallops taste good, even to fish. But the use of SVH as a specialty ingredient in aquafeeds, while potentially a good option, is not currently feasible because of the high costs of prototype development and the limited production capability due to the regulations that limit the landing of scallop viscera, leaving fishermen to chuck it overboard instead.
This may change as production and demand for these products scale up. Worldwide, the increasing demand for aquaculture feed is projected to outstrip the current supply, which will drive prices ever higher. Over time, these higher prices may expand the development of cheap sources of protein such as soybean meal and ingredients such as SVH that can be combined to create feeds suitable to meet the demand.
If regulatory and harvesting modifications are changed, they will ultimately benefit scallop fishermen and bring economic opportunity to the Rhode Island and Massachusetts fishing and processing industries while facilitating a sustainable seafood supply.
This story originally appeared in the Summer/Fall 2013 edition of 41°N, a publication of Rhode Island Sea Grant and the Coastal Institute at the University of Rhode Island.