Dechlorophyllization of Microalgae Biomass for the Bioconversion into Lipid-Rich Bioproducts

Chlorophyll is one of the most abundant pigments found in microalgae, which can affect the stability of its byproducts. The conventional bleaching procedure involves an adsorption approach, such as with clay and activated carbon, to remove chlorophyll from the oil, but this can cause disposal problems. Therefore, the present study proposed the novel pretreatment of biomass using sodium chlorite (NaClO₂) to remove chlorophyll from the microalgae prior to lipid extraction. The chlorophyll reduction and lipid loss rates were evaluated. The findings revealed that approximately 70% of the chlorophyll in biomass was removed using NaClO₂ and chlorophyll extraction solvents. The oil yielded by chlorophyll-reduced biomass was orange-green color, and extracted oil was very fluidic. In the treated biomass, the proportion of the saturated fatty acids reduced, whereas the unsaturated fatty acids level increased. Different treated biomass demonstrated a varied lipid loss rate, with 13% being the lowest for DMSO-NaClO₂. The biochemical composition including carbohydrate and proteins in treated biomass was not significantly different as compared to untreated biomass. In summary, the findings provide a useful pathway to remove chlorophyll that can serve as an alternative to the bleaching of microalgae oil in producing high-value lipid-based bioproducts.