Sammendrag
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.
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