Extração e caracterização de óleo de vísceras de rã-touro (Rana catesbeiana)

Abstract

The processing of bullfrog meat (Rana catesbeiana) produces a residue called fat body, rich in oil and/or fats. For the extraction of vegetable and animal oils the traditionally employed methods are pressing and/or the use of organic solvents, but the solvent extraction method has several drawbacks. In this sense, this research project aimed to characterize the fat body, to investigate the influence of temperature both in the press extraction as well as supercritical extraction. In the characterization of the fat body the observed average content of moisture was 4,23%, protein was 2,98%, ash was 0,18% and lipids was 92,52%. The extraction by pressing reached yields of 62.78% and 68.54% of final oil. The supercritical extraction with carbon dioxide achieved yields of 17.24%, 31.78% and 52.61% final oil. The observed acid value ranged between 2.32 and 2.86 KOH g-1. The peroxide values varied from 0.47 to 1.26 mEq kg-1. The fatty acid composition consisted of 75.5% of unsaturated fatty acids and 24.5% saturated fatty acids. The viscosity tests for oils obtained at different temperatures of mechanical extraction indicated that oils have a similar composition. The FTIR spectroscopy suggested that the oils obtained by both processes are similar. Calorimetric analysis was employed to evaluate the oxidative stability (OS), wherein that the extracted oil at 40°C presented the best OS. The obtained results evidence an alternative the potential of the fat body as a source of obtaining oil. Press extraction obtained high yields and was not influenced by the process temperature. On the contrary, the supercritical extraction using carbon dioxide was directly influenced by temperature and reached lower yields when compared to press extraction.