Chemical Composition and Texture of Commercial Geoduck Clams (Panopea abrupta) Harvested in Southeast Alaska

Abstract

The objectives of this study were to determine chemical composition of the siphon and the mantle of commercialsize geoducks clams harvested in Southeast Alaska, and to measure textural differences between the two muscle tissues, comparing them with their frozen counterparts. Live geoducks were processed using standard industry practices and analyzed either fresh or after 90 days of frozen storage. The mantle significantly differed in composition and texture from the siphon. The mantle had significantly higher contents of carbohydrates and lipids, whereas the siphon had a higher moisture content. Protein content was similar between tissues, but soluble protein content in the siphon was significantly higher than in the mantle. Large differences were observed in the electrophoretic profiles of the contractile siphon, which had a greater abundance of higher molecular weight proteins than the mantle. There were also textural differences in hardness and shear energy, with the siphon presenting significantly higher values than the mantle. After freezing, hardness values for the mantle significantly increased, and this finding is in line with Southeast Alaska geoduck processor observations. Overall, the composition and textural differences recorded are commensurate with differences in anatomic functions of the siphon and the mantle in live geoduck clams.