Quantification of triglyceride content in oleaginous materials using thermo-gravimetry

Laboratory analytical methods for quantification of triglyceride content in oleaginous biomass samples, especially microalgae, require toxic chemicals and/or organic solvents and involve multiple steps. In this paper, a simple triglyceride quantification method that uses thermo-gravimetry is described. This method is based on the observation that triglycerides undergo near-complete volatilization/degradation over a narrow temperature interval with a derivative weight loss peak at 420 °C when heated in an inert atmosphere. Degradation of the other constituents of oleaginous biomass (protein and carbohydrates) is largely complete after prolonged exposure of samples at 320 °C. Based on these observations, the triglyceride content of oleaginous biomass was estimated by using the following two-step process. In Step 1, samples were heated to 320 °C and kept isothermal at this temperature for 15 min. In Step 2, samples were heated from 320 °C to 420 °C and then kept isothermal at 420 °C for 15 min. Our results show that mass loss in step 2 correlated well with triglyceride content estimates obtained from conventional techniques for diverse microalgae and oilseed samples.