EFFECT OF DIFFERENT EXTRACTION METHODS ON THE CONTENT OF TOTAL PHENOLICS AND TOTAL FLAVONOIDS OBTAINED FROM Melipona flavolineata POLLEN

Pollen is an unconventional food, rich in proteins and biocompounds, which can be a source of macro and micronutrients for bees and humans. The present study aimed to evaluate the influence of the extraction method and the change of solvent in obtaining bioactive compounds from the pollen of the stingless bee Melipona flavolineata. In the first method, water was used as the extracting solution; in the second, methanol:water (60:40, v/v); and in the third, ethanol:water (70:30, v/v); the first two methods were performed in a thermostated bath (50° C/60 minutes) and the third in an ultrasonic bath (40Khz/35°C/30 minutes). The solids ratio was 3%, and, after extractions, centrifugation (10,000 rpm/20 minutes) and filtration were performed. The extracts were evaluated by analyzing total phenolic compounds – TPC (Singleton et al., 1999) and total flavonoids – TF (Pękal & Pyrzynska, 2014; Meda et al., 2005). The results for TPC were equal to 509.11 ± 22.59, 1838.35 ± 11.32, and 2804.63 ± 1.75 mg GAE/100 g for methods 1, 2 and 3, respectively. And for TF, they were equal to 139.40 ± 3.64, 85.74 ± 4.72 and 249.57 ± 7.57 mg QE/100 g for 1, 2 and 3, respectively. The greatest results obtained in ethanolic extraction can be justified by the intermediate polarity of ethanol, the interaction of ethanol through hydrogen bonds, and the reduction in surface tension. Furthermore, ultrasound extraction is reported to be more efficient, due to the cavitation effect generating microbubbles that expand and implode, leading to cell rupture, and greater penetration of the solvent into the tissues that releases the compounds more efficiently. Thus, the study revealed that the polarity of the solvent and the extraction conditions influenced the yield of bioactive compounds, which is useful to enable the application of more efficient and rapid methods for obtaining biocompounds on laboratory and industrial scales.