Academic article

Alternative protocols for the production of more sustainable agar-based extracts from Gelidium sesquipedale

Martinez-Sanz, Marta; Gomez-Barrio, Laura Pilar; Zhao, Ming; Tiwari, Brijesh; Knutsen, Svein Halvor; Ballance, Simon; Zobel, Hanne Kristine; Nilsson, Anna Ekman; Krewer, Christoffer; Östergren, Karin; Lopez-Rubio, Amparo

Publication details

Journal: Algal Research, vol. 55, p. 10, 2021

Publisher: Elsevier

International Standard Numbers:
Printed: 2211-9264

Open Access: none


Agar-based extracts from Gelidium sesquipedale were obtained by applying a conventional hot water treatment
and alternative ultrasound- and microwave-assisted methods, with and without the application of an alkaline
pre-treatment. The alkaline pre-treatment produced refined extracts with higher purity; however, extraction
yields increased from 2–5% to 7–19% by omitting this step. In particular, the ultrasound-assisted extraction
allowed reducing 4-fold the extraction time, while keeping constant or even increasing the yield (up to 19% for
the 1 h extraction) with respect to the conventional protocol. Interestingly, the presence of proteins and polyphenols
conferred the semi-refined extracts a relatively high antioxidant capacity (19–24 μmol TE/g extract). The
refined extract produced by the standard protocol formed the strongest hydrogels (>1000 g/cm2). On the other
hand, the semi-refined extracts produced by the alternative protocols formed slightly stronger hydrogels
(337–438 g/cm2) than the refined counterparts (224–311 g/cm2), due to their greater molecular weights of the
former ones. LCA assessment showed lower global warming potential for the semi-refined extracts, especially the
ultrasound-assisted extraction, hence highlighting the potential of this method to produce more sustainable agarbased
extracts for food-related applications.