Innovative processing technology in agar recovery: combination of subcritical water extraction and moderate electric fields

Abstract

Emerging processing technologies are gaining importance due to ecological benefits and high extraction efficiency. Agarophytes are seaweeds highly recognized for their agar content. This work aimed at evaluating the potential of combining subcritical water extraction and moderate electric fields (MEF) for agar extraction. Different temperature and time binomials were applied, keeping the same severity factor, under subcritical water conditions with and without MEF. The influence in the agar extraction yields, its composition and technological properties was evaluated. Moderate electric fields proved to be a valuable tool in agar recovery, particularly for G. sesquipedale, improving agar's extraction yield up to 40% at 140°C in the presence of MEF. Applied treatments and extraction technologies did not affect gelling ability, rheological behaviour, structure, and molecular weight distribution of the obtained agars. Therefore, the feasibility of alternative processing technologies was demonstrated, with gains in efficiency and processing time.