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Projeto de investigação
Molecularly Imprinted Polymers for the Enrichment of Phenolic Compounds from Winemaking residues.
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A simple process to purify (E)-resveratrol from grape stems with a photo-molecularly imprinted sorbent
Publication . Bzainia, Amir; Dias, Rolando; Costa, Mário Rui
The present work focused on the development of a process of sorption-desorption to
purify (E)-resveratrol found in winemaking residues, specifically from the crude extract of
grape stems. The core element of this process is a photo-molecularly imprinted sorbent
(MIS) synthesized by means of the molecular imprinting technique (MIT). This sorbent is a
4-vinylpyridine rich polymer network which binds (E)-resveratrol at stereospecific sites.
Comparison of sorption isotherms of the MIS and its counterpart non-imprinted sorbent
(NIS) shows the higher capability of the MIS to bind (E)-resveratrol. It is noteworthy that
the size of MIS particles was larger than to those of the NIS (as found by scanning electron
microscopy analysis) facilitating its use in sorption-desorption processes without
reaching a high backpressure. The MIS was then used to purify (E)-resveratrol from grape
stems extract in a two-step purification procedure through a simple device. The initial
purification step permitted to increase the purity of (E)-resveratrol from 29% to 78% (34%
of recovery), whereas a further one took it to 87% (70% of recovery). The purified fractions
were obtained in hydroalcoholic medium and contained other bioactive stilbenes such as
(E)-Ɛ-viniferin. The results of this research provide a compelling proof of concept for
room-temperature photopolymerization, enabling the development of highly efficient
imprinted polymers as sorbents for purifying bioactive compounds from agricultural residues.
This significant advancement paves the way for its large-scale implementation in
a circular bioeconomy approach.
Selective fixed-bed fractionation of stilbene subfamilies from grape cane waste using a pyridine-amide adsorbent
Publication . Bzainia, Amir; Keller, Erik; Heeres, André; Costa, Mário Rui P.F.N.; Dias, Rolando
The selective separation of structurally analogous polyphenols from complex plant matrices remains a longstanding challenge in bioseparation engineering. This study introduces a custom-designed adsorbent, poly(2,6-bis(acrylamido)pyridine) (poly(BAAPy)), tailored for subfamily-level resolution of stilbenes obtained from crude grape cane extracts. Leveraging dual amide and pyridine functionalities, poly(BAAPy) achieves selective retention of oligomeric stilbenes (e.g., trans-ε-viniferin, miyabenol C) via multivalent hydrogen bonding and π-π stacking interactions. Comparative breakthrough experiments against commercial poly(4-vinylpyridine) (poly(4VP)) demonstrate superior oligomer retention across both ethanol-water and acetonitrile systems. In dynamic closed-loop adsorption mode, poly(BAAPy) enabled polarity-driven elution and achieved up to a 3.4-fold enrichment of stilbene oligomers, with their recovery in fractions containing ≥ 90 % oligomeric content in a single desorption cycle. Uptake profiles and adsorption selectivity coefficients confirmed poly(BAAPy)’s preference for oligomers under both ethanol-water and acetonitrile conditions. The total stilbene recovery was 75 %. Breakthrough data were fitted using both empirical (Clark, Thomas) and mechanistic models, revealing distinct adsorption dynamics for poly(BAAPy) versus a commercial poly(4VP) resin. This work demonstrates a sustainable valorisation route for grape cane waste, converting viticultural residues into a high-value source of bioactive compounds. The use of green solvents and fixed-bed adsorption aligns with circular economy principles and environmentally conscious separation processes.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
UI/BD/153688/2022