Study of pressurized fluid extraction (PFE) conditions to obtain extracts from Brazilian cherry seeds (Eugenia uniflora L.) rich in phenolic compounds

摘要

The Brazilian cherry has high carotenoids and vitamin C contents. The seeds are a waste in the juice and frozen pulp process and its extract is rich in phenolic compounds with high antioxidant potential. Pressurized fluid extraction (PFE) is a relevant process, since it is a technology that uses lower solvent viscosity with increasing temperature (T) and pressure (P). This work studied the extracts yield and the total phenolic content in different process conditions. PFE with ethanol was applied according to a CCD 2~4 (central composite design) to four parameters, temperature (T), static time (ST), the number of cycles (C), and the volume of solvent in each cycle (VF). TLC and HPLC were used for separation and to identify the compounds in these extracts. The fractions collected using HPLC were analyzed by mass spectrometry with electrospray ionization (ESI/MS). The extracts yield was 8.90 ± 2.45% and the total phenolic content ranged from 0.42 to 1.68 g GAE × 100~(-1) seeds. For yield and total phenolic compounds, T, ST and its interaction positively influenced the process. The two main fractions (F1 and F2) presented antioxidant activity. The F1 had a maximum absorbance in the bands 251-253 nm and 360-361 nm and F2 between 253-255 nm and 366 nm. Preliminary analysis of ESI/MS showed the most intense ion spectra m/z 263 for F1 and for the F2, the ion m/z 301 with precursor ion m/z 447, indicating a loss of rhamnoside [MH-146]. The ion m/z 301 is a typical fragment of quercetin with the loss of a fragment m/z 46 that generates the ion m/z 255 also present in the F2 spectrum. For F2 the ion m/z 447 previously indicates the presence of quercetin 3-O-β-rhamnoside (M = 448 uma).