Extraction of Oils from Oleaginous Yeast (Rhodotorula paludigena) using Polar and Nonpolar Solvents
Author : Nortez, Kendrick Bantillan
Major Adviser : Movillon, Jovita L.
Major Co-Adviser : Pajares, Irene G.
Committee Members : Bataller, Butch G.; Capunitan, Jewel A.
Year : 2020
Month : July
Type : Thesis
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Oleaginous yeasts have more than 20 % (w/w) lipid content in their cells and they are potential sources of oils for biodiesel production. However, the conventional solvents used, such as the chloroform-methanol mixture (1:1 v/v), in the extraction are toxic and cannot be industrially adopted. In this study, methods in extracting oils from the dried cells of Rhodotorula paludigena were evaluated and optimized by comparing three solvents and by optimizing incubation time and solvent loading. Chloroform-methanol mixture gave maximum percent crude yeast oil (% w/w) of 49.26 ± 0.74, followed by ethanol (35.45 ± 0.20), and isopropanol (30.09 ± 0.12). Then, ethanol and isopropanol were selected in determining the effects of incubation time (1 h, 5 h) and solvent loading (25 mL/g, 50 mL/g) on the percent crude yeast oil since these solvents are safer and eco-friendly. It was observed that the effect of these solvents is significant, and the percent crude yeast oil (% w/w) for ethanol and isopropanol ranges from 29.32 – 36.37 and 28.78 – 31.42, respectively. Ethanol was used as solvent in optimizing the incubation time and solvent loading using a response surface methodology (Central Composite Design). The predicted optimum conditions were 133.91 mins, and 31.52 mL ethanol/g yeast with a percent crude yeast oil (% w/w) of 33.65. The study concluded that ethanol and isopropanol can be used as solvents in extracting oils from the dried yeast biomass, although not as effective as the chloroform-methanol mixture. However, future studies can explore in using solvent-mixtures of these solvents and other green solvents, and in optimizing other parameters to yield higher percent crude yeast oil.
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