Pulsed electric field treatment enhances lipid bioaccessibility while preserving oxidative stability in Chlorella vulgaris

Highlights

• PEF increased (~ 3-fold) the lipid bioaccessibility (BA) of Chlorella vulgaris.

• Incubation after PEF is necessary to improve lipid BA.

• The same lipid BA was reached with incubation at 25/37 °C for 12 h or 4 °C for 48 h.

• Putative endogenous cell wall-degrading enzymes were identified with proteomics.

• PEF preserved the oxidative stability and cell integrity of C. vulgaris biomass.

Abstract

There is growing demand for gentle technologies to improve the lipid bioaccessibility (BA) of Chlorella vulgaris biomass while preserving cell integrity and therefore oxidative stability. Pulsed electric field treatment (PEF, 5 μs at 20 kV cm⁻¹, 31.8 kJ kg⁻¹_sus) led to an enhancement in lipid BA from 4–7.8% (untreated) to 18.7–20.9%. To reach such a level of BA, incubation in buffer after the treatment (12 h at 25/37 °C, 48 h at 4 °C) was required. As hypothesized, PEF preserved cell integrity, as shown by particle size and scanning electron microscopy analyses, as well as oxidative stability of the biomass over 3 months at 40 °C. Proteome analysis identified four proteins that may be involved in cell wall lytic activity during incubation after PEF. Future work should focus on further understanding the mechanism behind incubation after PEF and studying the potential effect played by endogenous cell wall-degrading enzymes.