Biorefinery of the macroalgae Ulva lactuca: extraction of proteins and carbohydrates by mild disintegration

Abstract

The effect of osmotic shock, enzymatic incubation, pulsed electric field, and high shear homogenization on the release of water-soluble proteins and carbohydrates from the green alga Ulva lactuca was investigated in this screening study. For osmotic shock, both temperature and incubation time had a significant influence on the release with an optimum at 30 °C for 24 h of incubation. For enzymatic incubation, pectinase demonstrated being the most promising enzyme for both protein and carbohydrate release. Pulsed electric field treatment was most optimal at an electric field strength of 7.5 kV cm−1 with 0.05 ms pulses and a specific energy input relative to the released protein as low as 6.6 kWh kgprot −1. Regarding literature, this study reported the highest protein (~ 39%) and carbohydrate (~ 51%) yields of the four technologies using high shear homogenization. Additionally, an energy reduction up to 86% was achieved by applying a novel two-phase (macrostructure size reduction and cell disintegration) technique.Electronic supplementary materialThe online version of this article (10.1007/s10811-017-1319-8) contains supplementary material, which is available to authorized users.

Biorefinery of functional biomolecules from algae

“…The macroalga under investigation contained 3.7 ± 0.3 % proteins, 54.9 ± 1.2 % carbohydrates, 22.8 ± 0.3 % ash and 4.9 ± 0.3 % lipids (DW). These compositions are in good agreement with the reported values for Ulva lactuca (De Pádua et al, 2004;Postma et al, 2018). The protein content is, however, significantly lower than the 12-18 (DW)% reported by Postma et al, (2018) for the same strain.…”

“…These compositions are in good agreement with the reported values for Ulva lactuca (De Pádua et al, 2004;Postma et al, 2018). The protein content is, however, significantly lower than the 12-18 (DW)% reported by Postma et al, (2018) for the same strain. This could be due to variations in culture conditions and season.…”

“…We have presented an IL-mediated process for the extraction of biomolecules from the macroalga U. lactuca and two approaches for their fractionation: two-phase partitioning and ultrafiltration. The experimental yields obtained with these approaches were compared to several studies in which the biorefinery of green macroalgae was investigated: Aqueous extraction and enzyme hydrolysis (Fleurence et al, 1995;Postma et al, 2018), alkali solubilisation (Fleurence et al, 1995), shear extraction (Postma et al, 2018), aqueous two-phase extraction (Fleurence et al, 1995), ultrasonication (Fleurence et al, 1995), pulsed electric fields (Polikovsky et al, 2016;Postma et al, 2018), IL-mediated extraction (Malihan et al, 2017(Malihan et al, , 2014Pezoa-Conte et al, 2015) and combination of technologies (Kandasamy et al, 2012;Wong and Cheung, 2001). The results are plotted in Fig.…”

“…Overall composition (DW) for the model organisms T. suecica (microalgae) and U. lactuca (macroalgae). Data from (Michels et al, 2014a;Schwenzfeier et al, 2011) and (De Pádua et al, 2004;Postma et al, 2018 (Ma et al, 2014), while other strains, such as Tetraselmis suecica can accumulate up to 45 % starch (Kermanshahi-pour et al, 2014). Cyanobacteria are well known to produce large quantities of poly-peptides and pigmented proteins (Olguín et al, 1994;Trautmann et al, 2016), whereas microalgae can reach up to 60 % protein content depending on the culture conditions (Becker, 2007).…”

“…Proteins are often embedded in a matrix of polysaccharides (Lahaye and Robic, 2007) which is difficult to access under mild conditions. The processes reported in literature include extraction in aqueous and alkaline media (Bleakley and Hayes, 2017;Fleurence et al, 1995), mechanical shear (Barbarino and Lourenço, 2005;Postma et al, 2018) and enzymatic treatments (Amano and Noda, 1992;Fleurence et al, 1995;Postma et al, 2018). Such processes often result in low extraction yields and purities .…”