The gray portion of tissue you refer to is a fatty deposit rich in omega-3 fatty acids and low in the natural pink pigments found in the rest of the fish. To get a handle on how the gray area affects flavor, we oven-roasted several fillets of salmon, then removed the gray portion from half of them and left it intact on the others. Only a few discerning tasters noted that the samples with the gray substance had an ever-so-slightly fishier flavor; most couldn’t tell the difference. It’s easy enough to remove the gray stuff by peeling off the skin of the cooked salmon and then scraping it away with the back of a knife, but the flavor difference is so minor that we don’t think it’s worth the hassle.
