A novel method of flash‐hydrolysis assisted pigment extraction (carotenoids) from microalgae biomass

Abstract

AbstractThe human body can easily convert β‐carotene into retinol (a precursor of vitamin A), a significant ingredient in dietary supplements. The need for commercial natural pigment production, including β‐carotene, has led to intensive research in this area. Processing after biosynthesis is a vital stage that involves the use of nontoxic solvents, efficient mechanical disruption of cells, and the isolation of the required compounds. With the growing popularity of green extraction methods and the increasing market demand for carotenoids due to their health benefits, the use of clean, nontoxic, flash‐hydrolyzed biomass for carotenoid production presents a significant advantage. Furthermore, the remaining biomass can serve as a protein source for animal feed, thereby aligning with the principles of the biorefinery concept. In this study, our aim was to optimize the disruption of cells in two microalgal species using flash hydrolysis (FH). We applied two distinct levels of pressure and four separate temperature conditions over a brief residence time. Following this, we employed an ethanol extraction method to assess the efficiency of carotenoid pigment extraction. Flash hydrolysis is a chemical‐free subcritical water‐based continuous‐flow process, injected with wet biomass slurry at a high temperature (150–250 °C) for a very short time (8–12 s) to obtain bioproducts. In this study, we discovered that the pigment β‐carotene constituted 0.04 to 0.3% of the dry biomass in the case of Chlorella vulgaris. Bands of lutein and zeaxanthin were also observed in the thin layer chromatography (TLC) analysis of the treated slurry. This was achieved under conditions of an effective temperature of 200 °C and a pressure of 1700 psi. The Arthrospira platensis (1Tex), β‐carotene yield was 0.014 to 0.021% of dry biomass. Some lutein and zeaxanthin bands were also found in the treated slurry with an effective temperature of 150 °C and 1000 psi pressure. This study reports pigment extraction by FH for the first time. It is a viable process to scale up high‐value natural products like carotenoids from microalgae at the industrial level without adverse environmental impacts. Due to low residence time, the temperature does not have a negative effect on pigments; cell rupture was accomplished effectively using water as a solvent. A considerable amount of pigment could be recovered from microalgae at specific combinations of temperature and pressure depending on the type of cell wall that microalgae possess.