Extracción en fase sólida: Aplicaciones al análisis cromatográfico de aceites y grasas vegetales

Applications of solid-phase extraction for the isolation of certain lipid classes prior to chromatographic analysis are given. More information was found for sterols and related compounds, polar phenols and contaminants such as polycyclic aromatic hydrocarbons. Detailed analytical protocols are presented and discussed in many cases.Se analizan las aplicaciones de la extracción en fase sólida para el aislamiento de ciertos lípidos previamente al análisis cromatográfico. La mayor parte de la información se refiere a los esteroles y compuestos relacionados, fenoles polares y contaminantes como los hidrocarburos aromáticos policíclicos. Se muestran y discuten numerosos protocolos analíticos en detalle

In house validated UHPLC protocol for the determination of the total hydroxytyrosol and tyrosol content in virgin olive oil fit for the purpose of the health claim introduced by the EC Regulation 432/2012 for \u201cOlive oil polyphenols\u201d

An ongoing challenge in olive oil analytics is the development of a reliable procedure that can draw the consensus of all interested parties regarding the quantification of concentrations above the required minimum value of 5 mg of bioactive "olive oil polyphenols" per 20 g of the oil, to fulfill the health claim introduced by the European Commission (EC) Regulation 432/2012. An in-house validated ultra-high performance liquid chromatography (UHPLC) protocol fit for this purpose is proposed. It relies on quantification of the total hydroxytyrsol (Htyr) and tyrosol (Tyr) content in the virgin olive oil (VOO) polar fraction (PF) before and after acidic hydrolysis of their bound forms. PF extraction and hydrolysis conditions were as previously reported. The chromatographic run lasts ~1/3 of the time needed under high performance liquid chromatography (HPLC) conditions, this was also examined. Eluent consumption for the same piece of information was 6-fold less. Apart from being cost effective, a larger number of samples can be analyzed daily with less environmental impact. Two external curves, detection at 280 nm and correction factors for molecular weight difference are proposed. The method, which is fit for purpose, is selective, robust with satisfactory precision (percentage relative standard deviation (%RSD) values < 11%) and recoveries higher than 87.6% for the target analytes (Htyr, Tyr). Standard operational procedures are easy to apply in the olive oil sector

Factores antioxidantes y prooxidantes en aceite de oliva con aroma a orégano y romero

The study was carried out to examine the presence of antioxidants and pro-oxidants in oregano and rosemary gourmet oils. Dry, ground plant material (5% w/w) was infused to olive oil for 24, 48 and 72 hours and then it was removed by filtration. All preparations were found acceptable using a panel test. The total polar phenol content increased 3.5 and 1.7 times in oregano and rosemary gourmet oils with respect to that of the control sample. A qualitative enrichment of the methanol:water fraction of olive oil with phenolic compounds from herbs were found using HPLC. No rosmarinic acid was detected in the gourmet oils. Vanillic acid was only found in the rosemary gourmet oil. The presence of flavonoids was assessed using TLC. a-Tocopherol content of the oil matrix was not changed after herb infusion. A significant increase was found in pheophytin, a,b-carotene and lutein content of oregano flavoured oils. The oxidative stability of gourmet oils was greater to that of the control using the Rancimat test. In photo-oxidation, oregano flavoured oil was less stable than the rosemary one. Total chlorophyll content may be a critical factor for the shelf life of these preparations. Suitable labelling suggesting avoidance of light may be useful for a safe domestic use.El estudio fue realizado para examinar la presencia de antioxidantes y pro-oxidantes en aceites de oliva con aroma a orégano y romero. El material vegetal seco y molido se añade al aceite de oliva en proporción (5% w/w) durante 24, 48 y 72 horas y posteriormente se elimina por filtración. Todas las preparaciones se encontraron aceptables usando un panel de catadores. El contenido de fenoles polares totales aumentó 3,5 y 1,7 veces, en aceites con aroma a orégano y romero, con respecto al de las muestras control. Un enriquecimiento cualitativo de la fracción metanol: agua del aceite de oliva, con compuestos fenólicos de las hierbas, se encontró usando HPLC. No se detectó ácido rosmarinico en los aceites estudiados. El ácido vanillinico solo se encontró en los aceites con sabor a romero. La presencia de flavonoides se evaluó usando TLC. El contenido de a-tocoferol del aceite matriz no cambió tras la infusión con hierbas. En aceites con aroma a orégano se encontró un aumento significativo en el contenido de feofitina, a,b-caroteno y luteina. La estabilidad oxidativa de los aceites fue mayor que las del control usando el test Rancimat. En foto-oxidación, los aceites con sabor a orégano fueron menos estables que los de romero. El contenido en clorofilas totales puede ser un factor crítico para la vida media de estas preparaciones. Un etiquetado que sugiera el evitar la luz puede ser aconsejable para un uso doméstico seguro

Toward a harmonized and standardized protocol for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO). The pros of a fit for the purpose ultra high performance liquid chromatography (UHPLC) procedure

\u3a4oward a harmonized and standardized procedure for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO), the pros of a recently published in house validated ultra high performance liquid chromatography (UHPLC) protocol are discussed comparatively with those of other procedures that determine directly or indirectly the compounds hosted under the health claim on "olive oil polyphenols" (EC regulation 432/2012). Authentic VOOs were analyzed with five different liquid chromatographic separation protocols and 1H-NMR one in five different laboratories with expertise in VOO phenol analysis within three months. Data comparison indicated differences in absolute values. Method comparison using appropriate tools (Passing-Bablok regression and Bland Altman analyses) for all protocols vs. the UHPLC one indicated slight or statistically significant differences. The results were also discussed in terms of cost effectiveness, detection means, standard requirements and ways to calculate the total hydroxytyrosol and tyrosol content. Findings point out that the in-house validated fit for the purpose UHPLC protocol presents certain pros that should be exploited by the interested parties. These are the simplicity of sample preparation, fast elution time that increase the number of samples analyzed per day and integration of well-resolved peaks with the aid of only two commercially available external standards. Importance of correction factors in the calculations is stressed

Toward a harmonized and standardized protocol for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO). The pros of a fit for the purpose ultra high performance liquid chromatography (UHPLC) procedure

Toward a harmonized and standardized procedure for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO), the pros of a recently published in house validated ultra high performance liquid chromatography (UHPLC) protocol are discussed comparatively with those of other procedures that determine directly or indirectly the compounds hosted under the health claim on 'olive oil polyphenols' (EC regulation 432/2012). Authentic VOOs were analyzed with five di erent liquid chromatographic separation protocols and 1H-NMRone in five di erent laboratories with expertise in VOO phenol analysis within three months. Data comparison indicated di erences in absolute values. Method comparison using appropriate tools (Passing-Bablok regression and Bland Altman analyses) for all protocols vs. the UHPLC one indicated slight or statistically significant di erences. The results were also discussed in terms of cost e ectiveness, detection means, standard requirements and ways to calculate the total hydroxytyrosol and tyrosol content. Findings point out that the in-house validated fit for the purpose UHPLC protocol presents certain pros that should be exploited by the interested parties. These are the simplicity of sample preparation, fast elution time that increase the number of samples analyzed per day and integration of well-resolved peaks with the aid of only two commercially available external standards. Importance of correction factors in the calculations is stressed

Impact of the malaxation temperature on the phenolic profile of cv. Cobrançosa olive oils and assessment of the related health claim

Phenolic compounds contribute to the bioactive properties of olive oil. However, olive oils can only support a health claim concerning the protection against oxidative stress depending on the polyphenolic concentration, requiring effective measures during extraction to preserve/enhance their concentrations. The effect of the malaxation temperature (22, 28 and 34 °C) on the phenolic profile was studied for industrially extracted cv. Cobrançosa oils. Higher malaxation temperatures decreased the contents of the majority of the chromatographically detected compounds (P<0.05, one-way ANOVA), enabling oils differentiation. This decreasing trend was observed for hydroxytyrosol and tyrosol bound forms, determinant for the health claim, which were also negatively affected by temperature, despite revealing that all the industrially extracted oils tested supported the health claim. The observed constant free to bound forms ratio showed that the temperature range tested had a minor effect on bound-forms hydrolysis, being both free and bound forms equally affected by temperature.The authors are grateful to the Foundation for Science andTechnology (FCT, Portugal) forfinancial support by national fundsFCT/MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) and to BioTecNorteoperation (NORTE‐01‐0145‐FEDER‐000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020‐Programa Operacional Regional do Norte. Ítala Marx acknowledges the Ph.D.research grant (SFRH/BD/137283/2018) provided by FCT. NunoRodrigues thanks the National funding by FCT- Foundation for Scienceand Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Phenolic Molecules in Virgin Olive Oils: a Survey of Their Sensory Properties, Health Effects, Antioxidant Activity and Analytical Methods. An Overview of the Last Decade Alessandra

Among vegetable oils, virgin olive oil (VOO) has nutritional and sensory characteristics that to make it unique and a basic component of the Mediterranean diet. The importance of VOO is mainly attributed both to its high content of oleic acid a balanced contribution quantity of polyunsaturated fatty acids and its richness in phenolic compounds, which act as natural antioxidants and may contribute to the prevention of several human diseases. The polar phenolic compounds of VOO belong to different classes: phenolic acids, phenyl ethyl alcohols, hydroxy-isochromans, flavonoids, lignans and secoiridoids. This latter family of compounds is characteristic of Oleaceae plants and secoiridoids are the main compounds of the phenolic fraction. Many agronomical and technological factors can affect the presence of phenols in VOO. Its shelf life is higher than other vegetable oils, mainly due to the presence of phenolic molecules having a catechol group, such as hydroxytyrosol and its secoiridoid derivatives. Several assays have been used to establish the antioxidant activity of these isolated phenolic compounds. Typical sensory gustative properties of VOO, such as bitterness and pungency, have been attributed to secoiridoid molecules. Considering the importance of the phenolic fraction of VOO, high performance analytical methods have been developed to characterize its complex phenolic pattern. The aim of this review is to realize a survey on phenolic compounds of virgin olive oils bearing in mind their chemical-analytical, healthy and sensory aspects. In particular, starting from the basic studies, the results of researches developed in the last ten years will be focused