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Characterization of phenolic compounds of OMW: toxicity and degradability by yeasts

Publication . Gonçalves, Cristiana; Ferreira, João P.; Lopes, Marlene; Falcão, Soraia; Peres, António M.; Cardoso, Susana M.; Belo, Isabel

The characterization of Olive Mill Wastewaters (OMW), focusing the phenolic compounds, is one of the aims of the present work. As a first approach to characterize the phenolic compounds of OMW, the extraction methods used were: a liquid-liquid extraction by acidified ethyl acetate and a solid-liquid extraction with acidified methanol. The analysis of these extracts by reversed phase liquid chromatography confirmed that hydroxytyrosol was the most abundant phenolic compound in OMW, and that this compound was more efficiently recovered by the solid-liquid extraction technique. It was also a goal of this work to study the phenolic compounds toxicity to some yeast strains. Among the phenolic compounds tested catechol is the most inhibitory one to the cells. The phenols degradation was quite difficult, particularly when more easily degradable carbon source is still present in the medium.

2008Conference object

Open access

Valorização das águas ruças: identificação de compostos antioxidantes

Publication . Falcão, Soraia; Peres, António M.; Domingues, Maria R.M.; Cardoso, Susana M.

Neste trabalho pretendeu-se determinar a composição em compostos fenólicos de amostras de efluentes líquidos provenientes de diferentes lagares de azeite do Norte de Portugal (Amarante, Mirandela, Castelo Rodrigo e Frieira). Para tal, as águas ruças foram extraídas com acetato de etilo, o extracto foi fraccionado por HPLC e as fracções foram analisadas por espectrometria de massa (ESI-MS e ESI-MSn). Este procedimento permitiu verificar que o composto maioritário era o hidroxitirosol, embora em concentração variável. As amostras continham ainda outros compostos fenólicos comuns, tais como o ácido clorogénico, o ácido cafeico, o ácido p-cumárico, o tirosol; secoiridoides como o ácido elenólico, o oleosideo, o verbascosídeo, a oleuropeína, o ligostrosídeo e alguns flavonóides como a luteolina, a quercetina e o glucosídeo da luteolina.

2011Conference object

Open access

Characterization of phenolic compounds of OMW: toxicity and degrability by yeasts

Publication . Gonçalves, Cristiana; Ferreira, João P.; Lopes, Marlene; Falcão, Soraia; Peres, António M.; Cardoso, Susana M.; Belo, Isabel

The olive oil extraction, performed by the 3-phases process, results on a large amount of an effluent, usually known as Olive Mill Wastewater (OMW). It is mainly produced in the Mediterranean area, with the exception of Spain that is one of the major producers but mostly use the 2-phases process. OMW represents a major environmental problem due to its high organic content, being characterized by a strong acidic smell and an intensive brown to dark color due to the presence of biodegradable, recalcitrant and biostatic compounds. OMW phytotoxicity can be attributed to the phenolic compounds (Lanciotti et al, 2005). Owing to their instability, OMW phenols tend to polymerise during storage into condensed high-molecular-weight polymers that are difficult to degrade (Crognale et al, 2006). Thus, uncontrolled OMW disposal can create severe risks to water and soil quality. OMW is currently concentrated by evaporation in open pools, but this method is not satisfactory because a black foul-smelling sludge, difficult to remove, is produced. Instead of disposal solutions an approach of using this waste as a resource to be valorized is of greater interest. In fact, OMW contains sugars, lipids, mineral elements and phenolic compounds (10 % of the organic matter) that could be either directly recovered by chemical extraction and subsequent purification, or utilized as a basis for fermentative processes.

2008Conference object

Open access

Oleuropein/ligstroside isomers and their derivatives in Portuguese olive mill wastewaters

Publication . Cardoso, Susana M.; Falcão, Soraia; Peres, António M.; Domingues, Maria R.M.

Olive mill wastewaters (OMW) are a potential source of biophenols, but they have a complex composition with many unknown phenolics. The analysis of purified methanol extracts from two Portuguese OMW by electrospray mass spectrometry in the negative mode showed [M-H]- ions at m/z 539 and m/z 523, corresponding respectively to oleuropein and ligstroside isomers which contain the glucose unit linked to its aromatic moiety. Also, the fragmentation pathway of the [M-H]- ions at m/z 863, 685 and 847 indicated the presence of a diglucoside derivative of the oleuropein isomer and of mono- and diglucosides of the ligstroside isomer, respectively. Moreover, the two OMW samples contained an elenoic derivative of the ion at m/z 685 and a degradation product (m/z 453) of the [M-H]- ion at m/z 523. Future studies focusing on the abundance of these compounds on OMW, as well as their bioactivities, will determine their possible industrial exploitation.

2011Journal article

Restricted access

New biophenols in olive mill wastewaters

Publication . Cardoso, Susana M.; Falcão, Soraia; Peres, António M.; Domingues, Maria R.M.

Olive mill wastewaters (OMW) have been attracting the attention of food and pharmaceutical industries, as it is a potential source of biophenols with a wide range of biological activities. This effluent produced in the olive oil industry contains approximately half of the total phenolic compounds of the olive fruit and it is currently exploited for industrial extraction of hydroxytyrosol [1]. Still, the phenolic composition of OMW is extremely complex, and many compounds are yet unidentified. In this context, the identification of unknown phenolic compounds can encourage the search of new bioactive compounds in OMW and contribute to further valorize this waste. In the present work, six new phenolic compounds were identified in Portuguese olive mill wastewaters. The phenolic extracts of OMW were obtained by methanol and were fractionated on Sep Pack C18 cartridges, by elution of the cartridges with 50% (v/v) methanol. The analysis of the purified fractions by electrospray mass spectrometry in the negative mode showed high relative abundant [M-H]− ions at m/z 539 and m/z 523, corresponding respectively to oleuropein and ligstroside isomers that contain the glucose unit linked to its hydroxytyrosol moiety. Glucoside derivatives of these compounds were also found in the two OMW samples. In particular, the fragmentation pathway of the [M-H]− ion at m/z 863 demonstrated the presence of a diglucoside derivative of the oleuropein isomer, while those of the ions at m/z 685 and m/z 847 were consistent with mono- and a di-glucosides of the ligstroside isomer, respectively. Moreover, the structure of an elenoic derivative of the ion at m/z 685 was also elucidated. Studies regarding the abundance and the biological activities of these compounds are now required to determine their possible industrial exploitation. [1] Agallias A., Magiatis P., Skaltsounis A.-P., Mikros E., Tsarbopoulos A., Gikas E., Spanos I., Manios T. (2007). J. Agric. Food Chem. 55: 2671-2676.

2010Conference object

Open access