Fractionation and characterization of marine macroalgae proteins

Abstract

Nowadays, we are facing a shift from animal-based protein sources to plant-based alternatives driven by global population growth and environmental issues. Plants and species from the marine environment (e.g., seaweed) are excellent protein sources, offering essential amino acids and health benefits. Seaweed are sustainable protein sources with a low environmental footprint. However, seaweed contains only up to 15% protein, less than crops like soy (35%), making further processing necessary to increase protein content for food use. In this work, milling and size classification were applied to five different seaweeds (P. palmata, G. verrucosa, C. crispus, U. lactuca, and F. vesiculosus) to produce fractions with different particle sizes and protein profiles. To study the influence of the downstream process, the produced fractions were further solubilized using the Osborne method and analyzed in terms of nutritional composition and optical microscopy, and protein was quantified and characterized using gel permeation chromatography (GPC) and FTIR-ATR. Results showed that the application of milling and size classification had no effect on the protein content of each fraction. However, after the Osborne fractionation methodology, seaweed proteins demonstrated higher affinity to water environments, with a maximum extraction yield obtained for the F. vesiculosus whole fraction (32.12 ± 1.56 g_protein/100 g_{algae protein}) and a minimum of 10.42 ± 0.52 g_protein/100 g_{algae protein} for the P. palmata coarse fraction. Moreover, GPC showed different protein molecular profile patterns between fractions of the same alga, and FTIR-ATR confirmed the presence of high carbohydrate content, as well as proteins.