It is customary to marinate fresh hirame by using konbu to enhance the glutamate and keep the fish a well-preserved for the days to come. The longer the marination the more flavors. Kobu-Jime is an extremely simple technique, but is credited with increasing the perceptible umami of the fish flesh to a great extent.

Results of the analysis showed that 100g of untreated fluke sashimi contains 12 mg of glutamate. Compare this with 100g of fluke sashimi treated with Kobu-Jime, which contains 320mg of glutamate. The Kobu-Jime treated fluke also contains greater levels of asparagine, the amino acid contained in kombu.