Ultra-high pressure-assisted extraction of phenolic compounds from watercress: characterization and process optimization
Artigo de Conferência
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resumo
Ultra-high pressure (UHP), usually in the range from 100 to 800 MPa, is a novel technology
increasingly used in the food industry as a cold pasteurizing method. UHP has also been reported
as a good alternative to the conventional methods of extraction of high added-value compounds
from plant materials, as it avoids the degradation of thermosensitive molecules and can improve
the process efficiency [1-2]. Therefore, this study was carried out to characterize the phenolic
profile of watercress (Nasturtium officinale R. Br., a fast-growing semiaquatic plant with medicinal
properties) [3] and optimize the UHP-assisted extraction of these compounds using the response
surface methodology. For this, freeze-dried watercress samples were processed according to a
five-level full factorial design combining the independent variables: processing time (t, 1.5–33.5
min), pressure (P, 0.1–600 MPa) and solvent (S, 0–100% ethanol, v/v). The individual and
grouped phenolic compounds (analysed by HPLC-DAD-ESI/MS) and the extraction yield were
used as response variables. The chromatographic analysis revealed that the phenolic profile was
constituted mainly by flavonoids, namely quercetin and isorhamnetin glycoside derivatives,
whereas phenolic acids were less abundant. In addition, four kaempferol glycoside derivatives
were identified for the first time in this species [5]. The developed theoretical models were
successfully fitted to the experimental data and used for extraction optimization. The UHP
conditions that maximized the extraction yield (crude extract) and the recovery of phenolic
compounds were as follows: t= 34 min, P= 531 MPa, S= 26% and t= 3 min, P= 600 MPa, S=
100%, respectively [2]. In conclusion, the developed extraction process promoted the selective
extraction of phenolic compounds from watercress using a green solvent and reduced extraction
times.
