Extraction and stability of R-phycoerythrin from the macroalga Palmaria palmata using conventional and nonthermal processes

Macroalgae are highlighted for their rich nutritional composition and established consumption traditions. The red seaweed species Palmaria palmata is recognized as a valuable source of R-phycoerythrin (R-PE). Pulsed electric fields (PEF) is a nonthermal process often applied to food products to increase the extraction yield of intracellular compounds. In the current study, PEF was applied to Palmaria palmata as a pre-treatment to improve R-phycoerythrin extraction. Different extraction (solvent, particle size) and PEF processing parameters (voltage, treatment duration) were tested to identify the most efficient extraction conditions and the most critical parameters for obtaining the highest yield. The storability of R-PE was also assessed (light presence and temperature). The most efficient solvent was sodium phosphate buffer 0.02 M with a 1:20 solid-to-liquid ratio, leading to a yield of 2.05±0.07 mg/g on a dry basis. A milling step in liquid nitrogen further reduced the macroalgae’s particle size from 1600 to 600 μm, doubling the extraction yield of R-PE. The effect of storage conditions on the stability of R-PE was tested, and it was observed that after 2 and 4 h of storage, light exposure led to 23% and 31% pigment degradation, respectively. The best-performing PEF condition increased R-PE yield from 5.39 mg/g to 7.39 mg/g on a dry-basis. The electric field strength and the treatment time were identified as the most critical parameters affecting the R-PE yield. PEF processing and reducing the particle size were the most efficient aspects that improved the extraction yield.