The potential of lipid droplets from the microalga Chlamydomonas reinhardtii as natural emulsions

Microalgal lipid droplets (LDs) are a promising and potentially more sustainable alternative to seed oils. This study aimed to investigate the extraction and stability of microalgal LDs. LDs from cell wall-deficient Chlamydomonas reinhardtii were extracted in water using pulsed electric fields, achieving 81 ± 1 wt% lipid recovery. The extracts were evaluated for stability and stabilisation mechanisms under various processing and environmental conditions. LDs remained stable during pasteurisation and homogenisation, whereas sterilisation and freeze–thaw cycles induced coalescence. Stability testing across pH and ionic strengths indicated electrostatic repulsion as the main stabilisation mechanism, with possible steric contributions. Compared with seed-derived LDs, C. reinhardtii LDs displayed a broader pH stability range but weaker steric stabilisation. Odour changes, likely initiated during cell disruption, highlight the need to improve oxidative stability during extraction. Despite this, the study showcases microalgal LDs as a viable platform for additive-free emulsions, offering reduced land and fertiliser requirements relative to terrestrial crops. • Aqueous lipid droplet (LD) extraction from C. reinhardtii yielded 81 % of the lipids. • LDs were stable for ≥30 days and unaffected by pasteurisation. • LDs were mainly electrostatically stabilised and had an isoelectric point at pH 4.0 • Sterilisation and freeze-thawing led to LD aggregation and coalescence. • Aldehydes in LD extracts may stem from enzymatic oxidation during cell disruption.