A protein-rich extruded snack food made from local Hokkaido marine products was developed. The greater was the marine products weight-content, the smaller was the expansion ratio. The greater was the supplemental protein content, the greater was the expansion ratio.

The moisture of raw materials affected the expansion ratio, and there was an optimum moisture at which the expansion ratio reached a maximum. The heating temperature during extrusion cooking affected the expansion ratio and the proximate composition of the snack. The snack was more macronutritionally balanced than comparable snack products in its class on the market.