New processes ensure not a gram of salmon goes to waste
Scientists at Norway's Stiftelsen for industriell og teknisk forskning (SINTEF) are working on ways to turn as much of a salmon as possible into useful products, including food supplements and fire retardants. By using new low-temperature processes, the goal is to use every last gram of the fish.
As anyone who has bought a whole salmon and asked the fishmonger to fillet it can tell you, the price of the fish includes a lot of what isn't going to end up on the plate. In fact, this "junk" makes up 60 percent of the salmon's original weight. For the home cook, this can be used to make fish stock, but for the SINTEF team, it's raw material for a wide variety of products.
After a salmon is cleaned and filleted, what's left over are blood, viscera, trimmings, bones with flesh attached, heads, skins, and belly flaps. These may not look like much laid out on the cutting table, but they are the raw material for an array of products, including animal feed, food products, minerals, collagen, gelatin, pharmaceuticals, proteins, peptides, oils, food supplements, and Polyunsaturated Fatty Acids (PUFA).
This piscine productivity is well-established, but in recent years it's been recognized that things could be more efficient with less waste at the end of the day. One reason for this is that many of the processes for extracting oils are carried out at temperatures of 90 °C (196 °F), which get out the oil, but at the cost of damaging some of the oils and proteins.
Led by Rasa Slizyte, the SINTEF team has developed an inexpensive, lower-temperature alternative that causes less damage and produces a product of higher quality. The problem is that low-temperature extraction leaves the oil, proteins, and gelatins with a fishy taste and odor that can be pretty off-putting to some people.
"Fish taste is usually not desired when working with marine-derived health food products and ingredients," says Slizyte. "For this reason, we’ve developed a more sensitive, low-temperature method, which involves first extracting the oil and then using a washing technology to remove unwanted taste components from the proteins. We are then left with pure, taste-neutral proteins."
According to the team, the proteins extracted by the new method taste no stronger than pea or whey proteins, and the oils are suitable to sell as a stand-alone product or as an ingredient in health foods. Aside from foods, salmon leftovers can be used to make a natural, non-toxic fire retardant, which is derived from the pure bone meal, while fish gelatin could help meet high demand for gelatin among vegetarians and those who don't eat pork or pork-related products for religious reasons.
“Our technology is inexpensive, easy to apply and offers outstanding utilization of the restraw materials”, says Slizyte. ”Moreover, the products are of higher quality than those manufactured by current methods.”