Mechanical disintegration and particle size sieving of Chondrus crispus (Irish moss) gametophytes and their effect on carrageenan and phycoerythrin extraction

Abstract

To better understand the migration properties of hybrid carrageenan from the seaweed tissue during carrageenan extraction, the effect of increasing the seaweed surface area by the mechanical disintegration of gametophyte Chondrus crispus chips was studied under various temperature and time extraction conditions. Dried Chondrus crispus seaweed chips were milled by a rotor beater mill and classified into eight different size fractions by sieving with varying mesh sizes from 50 to 2000 µm. During extraction at 22◦ C, the red color of the filtrate increased significantly with the decreasing particle size of the fraction, correlating with the increasing phycoerythrin concentration (from 0.26 mg PE/g dry seaweed in the >2000 µm size fraction to 2.30 mg PE/g dry seaweed in the <50 µm size fraction). On the other hand, under the same extraction conditions, only a small increase in carrageenan precipitate was obtained with the decreasing size fractions (from no recovery in the >2000 µm size fraction to 2.1 ± 0.1 g/kg filtrate in the <50 µm size fraction). This yield was significantly lower than the ones from extractions at 45◦ C (5.4 ± 0.1 g/kg) or at 90◦ C (9.9 ± 2.1 g/kg) for the same particle size and time conditions. It could be concluded that hybrid carrageenan extraction is not surface area dependent, while phycoerythrin is. Therefore, it seems that phycoerythrin and carrageenan extraction follow different mechanisms. This creates potential for the selective extraction of each of those two compounds.