Browsing by Author "Duarte, Cristina Nogueira"
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- Chemical characterization and bioactive properties of different winemaking residues towards their valorizationPublication . Duarte, Cristina Nogueira; Dias, Maria Inês; Heleno, Sandrina A.; Dias, Rolando; Barros, Lillian; Amaral, Joana S.In the last decades, there has been an increasing concern in the search for strategies towards the valorization of agricultural residues. Annually, wine production is responsible for the generation of large quantities of phytotoxic waste, whose disposal is challenging as these residues can be hazardous to the environment when they are overused as fertilizers or simply discarded [1]. However, some of these residues can be a source of interesting compounds such as proteins, fibers, and phenolic compounds. In particular, the bioactive phenolic molecules have attracted considerable attention from the pharmaceutical, cosmetic, and food industries. Up until now, different studies have been conducted on the characterization of grape pomace and their components such as seeds, skins, and stems, particularly focusing on residues from red grape varieties [2]. However, less attention has been paid to other by-products generated during winemaking such as residues from white wine production, wine lees, and diatomaceous earth, which are used in the filtration of wine and represents approximately 250 tons/year of residues from the wine sector just in Portugal. In this context, as part of the project BacchusTech that seeks to develop a new innovative process, including the extraction, purification, and concentration of bioactive compounds present in winemaking residues, this work aimed in characterizing the pomace obtained from red and white wines production, the residues obtained after white pomace distillation, wine lees and diatomaceous earth in terms of phenolic compounds composition and extracts bioactivity. The residues were extracted using an hydroalcoholic solvent (80%, v/v), total phenolic compounds were estimated using the Folin-Ciocalteu reagent and individual phenolic compounds were identified and quantified by liquid chromatography coupled to mass spectrophotometry (HPLCDAD- ESI-MS/MS). Additionally, the biological activity was assessed through TBARS, DPPH, and reductive power assays to determine the antioxidant activity, and the antimicrobial activity was evaluated by broth microdilution against eight bacteria and two fungi. The non-anthocyanin and anthocyanin phenolic composition were in accordance with the previously reported by Sun et al. and He et al. [3,4], respectively, in red wines. Fifteen non-anthocyanin phenolic compounds were found, five phenolic acids (gallic acid and derivatives, p-hydroxybenzoic and p-coumaric acid), four flavan-3-ols (procyanidin dimers), two O-glycosilated flavanols (isorhamnetin and quercetin derivatives), three flavanol aglycones (quercetin, kaempherol, and myricetin), and one unknown compound. Regarding anthocyanins, five compounds were found, namely malvidin derivatives linked to acyl groups. Wine lees and white grape pomace before distillation presented the highest amounts of phenolic compounds; however, only diatomaceous earth sample reveal the presence of O-glycosylated flavonoids. All samples showed antibacterial and antifungal activity against most of the tested microorganisms, especially the red and white grape pomace before distillation and diatomaceous earth in the bacteriostatic activity and the wine lees in the fungistatic activity. In general, all samples showed promising antioxidant capacity, with very good results being obtained on TBARS assay, particularly for the white pomace after distillation (EC50 = 0.016±0.002 mg/mL), diatomaceous earth (EC50 = 0.063±0.001 mg/mL) and in red pomace before distillation (EC50 = 0.08±0.04 mg/mL). Overall, the obtained results demonstrated that the evaluated wastes are good sources of bioactive compounds, namely anthocyanins and other phenolic compounds, that can be used as raw materials for subsequent steps of concentration, purification and/or isolation of added-value compounds.
- Chemical characterization and bioactive properties of wine lees and diatomaceous earth towards the valorization of underexploited residues as potential cosmeceuticalsPublication . Duarte, Cristina Nogueira; Taofiq, Oludemi; Dias, Maria Inês; Heleno, Sandrina A.; Santos-Buelga, Celestino; Barros, Lillian; Amaral, Joana S.Annually, wine production is responsible for generating large quantities of residues, which are frequently disposed of and not valorized. So far, different studies have been conducted on grape pomace, yet less attention has been paid to other residues, such as wine lees and diatomaceous earth used in wine filtration. In this context, this study aimed to evaluate and compare the phenolic profile of these underexploited winemaking residues and assess their biological potential based on their antioxidant, antimicrobial, cytotoxic, and anti-aging activities (inhibition of tyrosinase and collagenase). Twenty-nine phenolic compounds, including twelve anthocyanins, were tentatively identified in the residues, with red grape pomace showing the highest diversity of compounds. The diatomaceous earth presented the highest content of non-anthocyanin phenolic compounds, being particularly rich in flavan-3-ols and myricetin-O-hexoside, and also presenting two anthocyanins. This sample also showed a high antioxidant activity, evidencing the best result in the reducing power assay. The red wine lees extract, despite showing a low content of phenolic compounds and less antioxidant activity, presented the highest inhibition capacity of bacteria growth. The extracts did not exhibit cytotoxicity against keratinocyte (up to 400 mu g/mL) and fibroblast (up to 100 mu g/mL) skin cell lines. However, the capacity of inhibiting tyrosinase and collagenase was low for the lees and diatomaceous earth, contrary to the grape pomace, seeds, and skins extracts that showed promising results, evidencing its potential as a cosmeceutical. Overall, this study highlights for the first time the potential of diatomaceous earth, an underexploited winemaking waste, in the obtention of added-value extracts and/or ingredients for cosmetic industry.
- Chemical characterization, antioxidant and antimicrobial activities of winemaking industry by-productsPublication . Duarte, Cristina Nogueira; Dias, Maria Inês; Heleno, Sandrina A.; Santos-Buelga, Celestino; Dias, Rolando; Barros, Lillian; Amaral, Joana S.The exploitation of bioactive compounds trom agri-food by-products has been attracting an increasing interest from different industries within a circular economy context since several of compounds may have health properties or be used as natural colorants or preservatives. So far, several studies have been developed on the characterization of red wine grape pomace and its components (seeds, skins, and stems). However, less attention has been paid to other by-products, such as grape pomace from white wine, the residues after distillation, wine lees, and diatomaceous earth, the latter used in the filtration of wine and corresponding to about 250 tons/year of waste in Portugal. In this work, samples of these by-products were evaluated for their chemical composition by HPLC-DAD-ESI-Msn and bioactivities (antioxidant activity by TBARS, DPPH, and reducing power assays, and antimicrobial activity against eight bacteria and two fungi). Fifteen non-anthocyanin phenolic compounds were found, including 5 phenolic acids, 4 flavan-3-0Is, 2 0- glycosylated flavanols, 3 flavanol aglycones, and one unknown. In the red wine byproducts 12 anthocyanins were detected, most being malvidin derivatives. Wine lees and white grape pomace before distillation presented the highest contents of phenolic compounds. Ali samples showed antibacterial and antifunga! activity against most of the tested microorganisms, with red and white grape pomace and diatomaceous earth having the best bacteriostatic activity, while the lees stood out against fungi. Ali samples showed promising antioxidant capacity, with very good results obtained on TBARS for the white pomace after distillation and diatomaceous earth. Overall, the results show that besides grape pomace other wine industry byproducts are also good sources of bioactive compounds with high potential for exploitation.
- Chemical composition and biological activity of different residues obtained from the wine industryPublication . Duarte, Cristina Nogueira; Dias, Maria Inês; Heleno, Sandrina A.; Santos-Buelga, Celestino; Dias, Rolando; Barros, Lillian; Amaral, Joana S.In recent years, the bioactive compounds present in agri-food sub-products have attracted increased attention due to their health benefits and advantages within a circular economy context. Annually, wine production is responsible for the production of large amounts of phytotoxic waste, which elimination is considered challenging since these residues can be hazardous to the environment when used as fertilizers or just discarded. Phenolic compounds are secondary metabolites processed by plants that have shown several health benefits, acting as antioxidants, antimicrobials, anticarcinogenic, or antidiabetics, among others. Bioactive phenolic molecules have attracted considerable attention from the pharmaceutical, cosmetic, and food industries. So far, several studies have been developed on the characterization of grape pomace and its components (seeds, skins, and stems), especially directed to the residues of red varieties.1 However, less attention has been paid to other by-products generated during winemaking, such as waste from the production of white wine, wine lees and diatomaceous earth. The latter is used in the filtration of wine and constitutes about 250 tons/year of waste from the wine sector in Portugal alone, making it a very pertinent residue with still scarce information being found in the literature. In this context, within the framework of the BacchusTech project that seeks to develop new innovative processes, comprising the extraction, purification, and concentration of bioactive compounds present in winemaking residues, different residues including pomace, lees and diatomaceous earth were evaluated for their chemical composition and bioactivities. Residues were extracted using an hydroalcoholic solvent (80%, v/v), total phenolic compounds were estimated using the Folin- Ciocalteu reagent and individual phenolic compounds were identified and quantified by liquid chromatography coupled to mass spectrophotometry (HPLC-DAD-ESI-MSn). Additionally, the biological activity was assessed through TBARS, DPPH, and reducing power assays to determine the antioxidant activity, and the antimicrobial activity was evaluated by broth microdilution against eight bacteria and two fungi. The phenolic composition was in accordance with the previously reported in red wines.2,3 Fifteen non-anthocyanin phenolic compounds were found, five phenolic acids (gallic acid and derivatives, p-hydroxybenzoic and p-coumaric acid), four flavan-3-ols (procyanidin dimers), two O-glycosylated flavanols (isorhamnetin and quercetin derivatives), three flavanol aglycones (quercetin, kaempferol, and myricetin), and one unknown compound. Regarding anthocyanins, five compounds were found, namely malvidin derivatives linked to acyl groups. Wine lees and white grape pomace before distillation presented the highest contents of phenolic compounds; however, only diatomaceous earth sample reveal the presence of O-glycosylated flavonoids. All samples showed antibacterial and antifungal activity against most of the tested microorganisms. The best bacteriostatic activity was evidenced by the red and white grape pomace before distillation and diatomaceous earth, while the wine lees stood out for their fungistatic activity. In general, all samples showed promising antioxidant capacity, with very good results being obtained on TBARS assay, particularly for the white pomace after distillation (EC50 = 0.016±0.002 mg/mL), diatomaceous earth (EC50 = 0.063±0.001 mg/mL) and red pomace before distillation (EC50 = 0.08±0.04 mg/mL). Overall, the results obtained showed that the residues analyzed are good sources of bioactive compounds, namely anthocyanins and other phenolic compounds, which can be used as raw materials for the steps of concentration, purification and/or isolation of compounds of added value.
- Didactic analysis of olive mill wastewaters antimicrobial activityPublication . Afonso, Inês Santos; Duarte, Cristina Nogueira; Ribeiro, António E.; Amaral, Joana S.; Ribeiro, J.E.The olive oil production industry is a relevant economic activity in the Mediterranean countries. However, in the extraction process a large amount of a residual effluent called olive mill wastewaters (OMWW) is produced, which represents a large environmental problem. The physicochemical composition of the OMWWis variable but can be characterized by a high organic load, acidic pH, intense oily smell, and a dark brown colour. The high-level organic complexity contributes to their biodegradability resistance, causing negative environmental effects. Up until now, a globally standardised treatment for this residue has not been defined, mainly due to technical and economic limitations. However, this residue has the potential for being used in different areas, being converted from an environmental problem to a possible solution. In this work, the total phenolic content, antioxidant activity and the antimicrobial activity of two different OMWW against eight different microorganisms were evaluated. The results showed that OMWW has a good inhibitory power against different pathogenic bacteria, especially against Klebsiella pneumoniae, Staphylococcus aureus, Proteus mirabilis and Enterococcus faecalis, and therefore can potentially be exploited for their antimicrobial activity.
- Valorização de polifenóis contidos em resíduos da vinha e da oliveira usando adsorventes molecularmente impressosPublication . Duarte, Cristina Nogueira; Dias, RolandoEsta investigação teve como objetivo a avaliação de novos adsorventes para a valorização eficiente de resíduos da vinificação e da produção de azeite através da obtenção de produtos de valor acrescentado, especificamente polifenóis. Foram projetados e sintetizados diversos materiais molecularmente impressos (MIPs), considerando diferentes tipos de moléculas molde e variando a sua composição química e características morfológicas. Tendo em consideração estudos recentes nesta área, a 4-vinilpiridina (4VP) foi usada como monómero funcional na generalidade dos adsorventes sintetizados. Procurou-se potenciar a forte interação entre os grupos piridil e muitos polifenóis. Para efeitos comparativos, foram também realizados testes de adsorção/desorção de polifenóis com materiais sintéticos disponíveis comercialmente. Produziram-se extratos de bagaço, antes e após a destilação, considerando diferentes solventes para remoção dos polifenóis, nomeadamente etanol/água 80/20, acetonitrilo/dimetilformamida (50/50) e acetato de etilo/etanol (50/50). Usou-se a água ruça de uma cooperativa de produção de azeite como possível fonte de polifenóis de produtos derivados da oliveira. Procedeu-se à análise por HPLC-DAD dos extratos para obtenção dos respetivos perfis em termos de compostos fenólicos. Realizaram-se testes de retenção dos polifenóis contidos nos extratos de bagaço e na água ruça utilizando os diferentes adsorventes. Notavelmente, as medições realizadas demonstram uma superior capacidade dos materiais sintetizados com 4VP para reter os polifenóis presentes nos diversos extratos de bagaço e também na água ruça. Os resultados obtidos mostram que a elevada capacidade de retenção de polifenóis com adsorventes 4VP se verifica com extratos em solventes muito diferentes, incluindo solventes orgânicos e misturas aquosas, confirmando observações análogas com outras matrizes vegetais. Analisou-se a dinâmica de adsorção de polifenóis contidos em extratos de bagaço e na água ruça com adsorventes MIP selecionados e considerando processos fechados ou contínuos. Testou-se a concentração e fracionamento dos polifenóis através de ciclos de adsorção/desorção. Com um extrato de bagaço foi demonstrada a simplificação do perfil fenólico original e produzida uma fração enriquecida em flavonoides. Com a água ruça foi produzida uma sequência de frações orgânicas mostrando o enriquecimento alcançado com secoiridóides e flavonoides, relativamente a álcoois e ácidos fenólicos. Os adsorventes 4VP mostraram-se também promissores para a melhoria da eficiência no tratamento de águas ruças e águas da curtição da azeitona.