Kinetics of pulsed electric fields assisted pigment extraction from Chlorella pyrenoidosa

Abstract

Kinetics οf chlorophyll extraction from the microalga Chlorella pyrenoidosa, assisted by Pulsed Electric Fields (PEF), were studied. Treated (4.6 kV/cm, 0–179.2 kJ/kg) and untreated biomass was suspended in ethanolic solutions (75–95% v/v) and incubated at 30–60 °C for up to 6 h. Higher PEF treatment specific energy, ethanolic content of extraction solvent and extraction temperature led to higher recovery of pigments and antioxidants (chlorophyll and lutein, respectively). Chlorophyll characteristic extraction time depended only on extraction temperature (2.16 h at 30 °C vs. 0.61 h at 40 °C). A treatment of 179.2 kJ/kg before extraction with 95% ethanol at 60 °C for 4 h led to maximum recovery of both chlorophyll and lutein (18.2 and 1.17 mg/g dry biomass, respectively). Lutein was extracted more selectively at 30 °C which led to extracts with higher concentration in antioxidants (28.83 mg Trolox/g dry extract from treated samples with 179.2 kJ/kg and a four-hour extraction with 95% ethanol). Industrial relevanceChlorophylls and carotenoids from C. pyrenoidosa have garnered significant interest by the food industry for application as natural colorants and strong antioxidants in food products. Low energy requirements, short treatment times and selectivity establish Pulsed Electric Fields as a suitable technology to improve the extraction of these ingredients. An overall mathematical model of chlorophyll extraction, incorporating all process parameters, is a useful industrial tool for reliable predictions and the estimation of extraction efficiency under different process conditions.