Stirred, ultrasound-assisted and microwave-assisted extraction process of β-carotene from Rhodotorula glutinis in biorefinery downstream

Abstract

Due to the general population awareness about the specific health hazards of synthetic chemical dyes, natural colorant materials have been gaining attention in the past several years. Among them, β-carotene is widely used as a soluble orange–red pigment in food industry, while also presenting medical care benefits. Thus, considerable efforts have been dedicated to the development of an efficient serial, cost effective and sustainable extraction process for its recovery. Herein, solid–liquid (SLE), ultrasound-assisted (UAE) and microwave-assisted (MAE) equilibrium separation were carried out using 4 organic solvents for β-carotene isolation of from Rhodotorula glutinis yeast. Results suggested that technique-wise, UAE performed similarly to SLE, whereas MAE was not as optimal. According to the solvent applied, the colorant followed the increasing trend: dichloromethane < diethyl ether < dimethyl carbonate < ethyl acetate. The latter resulted in 45 ± 3 μg g−1, 42 ± 2 μg g−1 and 41 ± 3 μg g−1, while being extracted with UAE, SLE and MAE, respectively. These operation findings show the positive relationship effect of the greener solvent during the SLE, UAE and MAE activity for the optimisation of high-added value molecular compound, pro-vitamin A, from fungi. Additionally, a diffusion-based model system was implemented for the first time to determine mass transfer phenomena. When correlated with experiments, good measurement accuracy was validated; hence, showing promising results as a predictive model in future research studies, especially mechanistic.