Strategies to improve carotene entry into cells of Yarrowia lipolytica in a goal of encapsulation

Yeasts are good materials for encapsulation of actives, but, as they are preformed capsules, they have to be loaded. Our goal was to load cells with a big and very hydrophobic molecule, beta-carotene (LogP approximate to 15). In classical conditions, the entry of this compound into cells is negligible and we have worked on ways to favor the entry through the cell wall. Carotene was prepared at 0.3-3 g L-1 in solvents to improve solubility and alter the cell wall structure. After a 3 h-incubation of cells with this solution, with the apolar hexane, the entry was increased to 95 mu g g(-1) cell wet weight but the monopolar chloroform was much more efficient (220 mu g g(-1) cell wet weight). However, increasing the carotene concentration in chloroform increased the adhesion of carotene on the cell wall (over 900 mu g g(-1) cell wet weight) but did not increase the amount into the cell. The use of ultrasound (6-min-treatment at 50% and an output control of 4) as a green physical treatment increased significantly the result for beta-carotene encapsulation (852 mu g g(-1) cell wet weight). (C) 2017 Elsevier Ltd. All rights reserved.