In this study, the percentage content of free steroid in oils, fats and biodiesel was analyzed. For this, the saponification reaction on a microscale was used, and this procedure for extraction of unsaponifiable fraction was studied in several experimental steps. After the process of saponification, the unsaponifiable fraction was analyzed by gas chromatography with flame ionization detector, where all steroids present in each oil, fat and biodiesel were identified and their contents determined and compared to their respective biodiesel. A reduction in unsaponifiable fraction of each oil and fat and its biodiesel was noted, as well as a reduction in the content of free steroids. The results showed that, compared to the sedimentation problem of steroids in biodiesel, some raw materials, such as chicken fat and babassu oil may be promising because they have low content and high reduction percentages of steroids when converted to biodiesel.

O estudo sobre os esteróides livres e sua utilização na caracterização de óleos é interessante já que sua distribuição é diferente para cada óleo. Embora vários trabalhos mostrem a análise desses esteróides em óleos, um trabalho mais abrangente mostrando a presença de esteróides menos abundantes ainda é limitado. Os esteróides foram extraídos a partir da matéria insaponificável usando reação de saponificação em microescala. Após a extração os esteróides foram caracterizados por cromatografia gasosa (GC) utilizando os detectores por ionização de chama (FID) e espectrometria de massas (MS). Todos os picos cromatográficos presentes nos óleos que poderiam ser de esteróides livres foram caracterizados e quantificados. Os resultados evidenciaram grande diversidade de tipos e teores de esteróides livres. Os óleos de milho e moringa apresentaram maiores teores de esteróides em relação aos outros óleos analisados. Os óleos de babaçu, palmiste e canola foram os que apresentaram os menores teores.

The study of free steroids and their use in oil characterization is interesting because the distribution of these steroids varies from one oil to another. Although several papers analyze the most abundant steroids in oils, studies including less common steroids are scarce. Free steroids were extracted from unsaponifiable fraction using the saponification reaction adapted micro-scale. After extraction, steroids were characterized by gas chromatography (GC) using flame ionization (FID) and mass spectrometry (MS) detectors. All chromatographic peaks in the oils that could belong to free steroids were characterized and quantified. Results evidenced great diversity in types and levels of free steroids. Corn and moringa oils had higher levels of steroids than the other oils analyzed. Babassu, palm kernel and canola oils had the lowest steroid levels.