The use of antioxidants in feed in order to minimize the occurrence of oxidative rancidity and guarantee the quality of the food is a common practice in industries. Synthetic antioxidants are the most used, but they can present important toxicity dangers for the animal and the final consumer. Thus, this research project proposes the production, characterization and comparison of ethanolic and acetone extracts of Spirulina (Arthorspira) platensis, in order to verify the ability to present themselves as natural alternatives to the synthetic antioxidants currently used in fish diets. For this, S. platensis biomass will be acquired at the Aphoticário® handling pharmacy, the extracts will be prepared and the physical-chemical analyzes will be performed in triplicate. The total antioxidant capacity of the extracts will be determined colorimetrically after the ABTS cation reduction reaction. The determinations of humidity, total proteins, total lipids and ash will be performed for analysis of proximal composition. For the determination of the color, it will be used the CIELab space with the measurements made with the MiniScan XE Plus (Hunterlab) colorimeter calibrated with black and white standards, using D65 and 10 ° illumination for the observation angle. The extraction of the carotenoids from the samples will be performed with dimethyl sulfoxide and acetone. For the quantification of carotenoids, the dry extract will be dissolved in acetone and the absorbance will be read in a spectrophotometer at 475 nm. Carotenoids will be expressed as total carotenoids, in mg / kg. The results of the extract analyzes will be submitted to the t test to compare the techniques, with a level of significance of 5%, performed with the SAS 9.2 statistical package.
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