Anais do Simpósio Latino Americano de Ciências de Alimentos
Anais do 13º Simpósio Latino Americano de Ciência de Alimentos

The microalgae composition in proteins, lipids, carbohydrates, pigments and other compounds, such as sterols, make these microorganisms have high applicability in the food, supplements and additives industries. However, sterols analysis from complex matrices like as microorganisms can be very laborious and time-consuming. So, the aim of this study was to optimize a new micro-method for sterols (cholesterol, stigmasterol and β-sitosterol) and squalene determination in cyanobacteria biomass by gas chromatography (GC) to minimize the main analytical drawbacks. The optimization strategy applied to extraction/saponification and GC analysis of compounds were carried out separately using for both cases Plackett-Burman (PB) and central composite rotational (CCDR) designs, after it was also employed all the parameters of merit. In the first moment, it was studied diverse range of solvent polarity in the pretreatment step. Then, five independent variables were screened by a BP 16 run design for the sample preparation (pretreatment time, pretreatment temperature, KOH concentration, saponification time, saponification temperature) and introduction in the gas chromatography (injector temperature, volume of sample, pressure, initial column temperature, hot needle time). In a second moment, statistical models were constructed using significant variables to find the optimum response of sterols and squalene. Among the solvents chloroform presented higher capability to extract all the target compounds. The optimal condition reaches high arbitrary areas for all compounds. In this sense, the optimal sample pretreatment time was 90 min, at 50 °C, and saponification time of 6 min. Further, after five variables investigated to the sample introduction, positive effects were observed in the pressure and the injector temperature, that was established in 21 psi and 310 °C. Therefore, all the validation parameters were satisfactory. In this sense, the new micro-saponification method showed a great analytical performance, fulfilling all the steps for a complete sterol determination in cyanobacteria biomass.