Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods

• Published in: Journal of applied phycology Vol. 30; no. 6; pp. 3565 - 3580
• Main Authors: Harrysson, Hanna, Hayes, Maria, Eimer, Friederike, Carlsson, Nils-Gunnar, Toth, Gunilla B., Undeland, Ingrid
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.12.2018; Springer Nature B.V
• Subjects: Accelerated solvent; Algae; amino-acid; Ammonium; Ammonium compounds; Ammonium sulfate; Ammonium sulfate precipitation; Biologi; Biological Sciences; Biomedical and Life Sciences; Biotechnology & Applied Microbiology; Cell walls; Chemical precipitation; chemical-composition; Digestibility; Ecology; edible seaweeds; Fatty acids; Food; Foods; Freshwater & Marine Ecology; functional-properties; ingredients; Life Sciences; Lipids; macro and microalgae; macroalgae; Marine & Freshwater Biology; marine-algae; Methods; nutritional-evaluation; ods: implications and applications; p297; pH shift; pH shift method; Plant Physiology; Plant Sciences; Polyphenols; Polysaccharides; polyunsaturated fatty-acids; Porphyra; Porphyra umbilicalis; Protein extraction; Protein sources; Proteins; Removal; Saccharina latissima; Seaweed; Seaweed Protein extraction Ammonium sulfate precipitation pH shift Accelerated solvent extraction (ASE®) Amino acids; Seaweeds; Solubilization; Solvent extraction; solvents; Sonication; subtropical red; Sulfates; Ulva lactuca; v64; vegetable protein; Protein extraction; Seaweed; Amino acids; Ammonium sulfate precipitation; Accelerated solvent extraction (ASE®); pH shift
• DOI: 10.1007/s10811-018-1481-7
• ISSN: 0921-8971; 1573-5176

The demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds ( Porphyra umbilicalis , Ulva lactuca , and Saccharina latissima ). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE®) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P . umbilicalis (22.6 ± 7.3%) and S . latissima (25.1 ± 0.9%). The traditional method resulted in the greatest protein yield when applied to U . lactuca (19.6 ± 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 ± 3.7%, 51.2 ± 2.1%, and 40.7 ± 0.5% for P . umbilicalis , U . lactuca , and S . latissima , respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U . lactuca and S . latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed.