Extraction and technofunctional properties of protein-rich ingredients from Palmaria palmata (Dulse)

The global search for alternative protein sources for human consumption, other than those from animal origin, has increased and is currently attracting significant worldwide attention from consumers and food companies. This has led to the identification of several macroalgal species which may serve as good sources of high-quality protein. One of the macroalgal species identified, Palmaria palmata, also known as dulse or dillisk is a popular red macroalga that can contain up to 20% protein on a dry weight basis. P. palmata can be harvested from the wild or cultivated on land or at sea to meet market demand.

This thesis describes novel research on assessment of the protein content and quality of wild harvested P. palmata biomass obtained from different geographical locations throughout the west coast of Ireland during a two-year period. This work helped inform the selection of P. palmata from specific locations for subsequent growth trials on longlines cast at sea. Moreover, the impact of laboratory-scale culture with the addition of nutrient medium alone or with urea (0.05 or 0.10 g/L urea) or under different lighting regimes on the protein content and protein quality was also studied in this thesis. The protein components from specific laboratory grown P. palmata biomass samples were subjected to aqueous combined with alkaline extraction protocols for the development of P. palmata protein concentrates. In some instances, protein extraction was aided with the use of carbohydrases. A protein concentrate and it associated enzymatic hydrolysates which were generated at a semi-pilot scale from biomass obtained from longline-grown P. palmata was subsequently assessed for its technofunctional properties. The aim of these assessments was to determine the potential utility of these macroalgal proteinaceous ingredients in different food ingredient applications.