Chemistry and utilization of plankton. VII. Protein and amino acid compositions of five species of marine phytoplankton.

Abstract

In order to explore the possibility of utilizing marine phytoplankton as protein sources for human consumption, we elucidated the content and composition of protein fractions in five species of marine phytoplankton and analyzed their amino acid composition. The protein contents in four out of five species of phytoplankton examined were within a narrow range of 12.6-21.2g/100g dry matter. The composition of the proteins was quite variable from species to species but, as a whole, alkali-soluble fractions occupied the major part and the high ionic strength-soluble fractions which correspond to myofibrillar proteins in the muscle of animals were fairly low in contents. We also attempted to evaluate the nutritional value of phytoplankton proteins on the basis of the amino acid composition and found the essential amino acid indexes of two species of diatoms to be 93.3 and 89.1, indicating that the proteins of the diatoms are nutritionally excellent.