Olive leaves have always aroused an important interest, especially for folk medicine. Polyphenols contained in olive leaves have played an important role to this end, because they have demonstrated ...to be responsible for their anti-carcinogenic, anti-inflammatory, and antimicrobial proprieties. Olive leaves have common phenolics with other plants, but they also contain phenolics belonging to the secoiridoids family (exclusive to the Oleaceae family). Chemical, agronomical and medicinal researches have contributed together to highlight the interest in the use of olive leaves as a potential source of phenolic compounds for the production of functional food and nutraceuticals. The aim of this review is to provide a guideline summarizing the great information available about phenolic compounds of olive leaves. Therefore, from one side, it has been reported the availability of leaves as by-products, a brief description of the main phenolics identified in leaves, as well as the main analytical methods used for their extraction and determination. From another side, the effects of abiotic and biotic factors on the phenolic compound content in leaves have also been exposed for the first time, and finally, an overview of the main research studies dealing with the beneficial effects of olive leaves phenolic compounds has been included.
•Bioactive phenolic compounds in olive leaves are decribed•Overview of the protocols for the determination of phenolics in olive leaves.•Polyphenols as dynamic compounds under different biotic and abiotic influences: An important fact to take in account at olive leaves sampling•Health potentials of olive leaf phenolic compounds are summarized•Olive leaves are promoting by-products for functional food and/or nutraceuticals
This paper reviews the phenolic-compound-extraction systems used to analyse fruit and vegetable samples over the last 10 years. Phenolic compounds are naturally occurring antioxidants, usually found ...in fruits and vegetables. Sample preparation for analytical studies is necessary to determine the polyphenolic composition in these matrices. The most widely used extraction system is liquid-liquid extraction (LLE), which is an inexpensive method since it involves the use of organic solvents, but it requires long extraction times, giving rise to possible extract degradation. Likewise, solid-phase extraction (SPE) can be used in liquid samples. Modern techniques, which have been replacing conventional ones, include: supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). These alternative techniques reduce considerably the use of solvents and accelerate the extraction process.
We have developed a HPLC-DAD–ESI-MS method to profile the metabolic content of the methanol extract of three tomato cultivars grown in Almería (south-east Spain) and analyse the quantities of ...phenolic compounds present.
The consumption of tomatoes and tomato products has been associated with a reduction in the risk of contracting some types of cancer and other chronic diseases. These beneficial properties may be attributed to the presence of key metabolites and the interactions among them. We have developed and validated an analytical method for the comprehensive profiling of semi-polar metabolites in the methanol extract of three cultivars of raw tomatoes (Daniela, Raf and Rambo) grown in Almería, in south-east Spain. Diode-array and time-of-flight/ion-trap mass spectrometry detectors were used to ensure the wide detection of metabolites with highly divergent properties. The masses thus detected were assigned by matching their accurate mass-signals with tomato compounds reported in the literature, and supplemented by UV and MS/MS information, reference compounds and existing metabolite databases. In this way we were able to identify tentatively 135 compounds belonging to various structural classes, 21 of which are to our knowledge reported for the first time in the tomato fruit. Among the metabolites identified, the most abundant were phenolic compounds. This class of secondary metabolites is attracting considerable attention from producers and consumers due to their antioxidant activity and nutritional properties. Their quantitative analysis was achieved by using closely related derivatives for each family.
Over the last decades, olive oil quality and authenticity control has become an issue of great importance to consumers, suppliers, retailers, and regulators in both traditional and emerging olive oil ...producing countries, mainly due to the increasing worldwide popularity and the trade globalization of this product. Thus, in order to ensure olive oil authentication, various national and international laws and regulations have been adopted, although some of them are actually causing an enormous debate about the risk that they can represent for the harmonization of international olive oil trade standards. Within this context, this review was designed to provide a critical overview and comparative analysis of selected regulatory frameworks for olive oil authentication, with special emphasis on the quality and purity criteria considered by these regulation systems, their thresholds and the analytical methods employed for monitoring them. To complete the general overview, recent analytical advances to overcome drawbacks and limitations of the official methods to evaluate olive oil quality and to determine possible adulterations were reviewed. Furthermore, the latest trends on analytical approaches to assess the olive oil geographical and varietal origin traceability were also examined.
A new liquid chromatography methodology coupled to a diode array detector and a time-of-flight mass spectrometer has been developed for the simultaneous determination of phenolic compounds and ...saponins in quinoa (Chenopodium quinoa Willd). This method has allowed the simultaneous determination of these two families of compounds with the same analytical method for the first time. A fused-core column C18 has been used, and the analysis has been performed in less than 27 min. Both chromatographic and electrospray ionization time-of-flight mass spectrometry parameters have been optimized to improve the sensitivity and to maximize the number of compounds detected. A validation of the method has also been carried out, and free and bound polar fractions of quinoa have been studied. Twenty-five compounds have been tentatively identified and quantified in the free polar fraction, while five compounds have been tentatively identified and quantified in the bound polar fraction. It is important to highlight that 1-O-galloyl-β-d-glucoside, acacetin, protocatechuic acid 4-O-glucoside, penstebioside, ethyl-m-digallate, (epi)-gallocatechin, and canthoside have been tentatively identified for the first time in quinoa. Free phenolic compounds have been found to be in the range of 2.746–3.803 g/kg of quinoa, while bound phenolic compounds were present in a concentration that varies from 0.139 and 0.164 g/kg. Indeed, saponins have been found to be in a concentration that ranged from 5.6 to 7.5% of the total composition of whole quinoa flour.
Traditional thermal techniques may cause losses in nutritional quality and phytochemical contents, and also in physicochemical, rheological, and organoleptic properties of processed fruit juices. ...This paper provides an overview of the effect on these qualities by the use of alternatives to traditional thermal treatments in fruit-juice processing, for three key operations in fruit-juice production such as microbial inactivation, enzyme inactivation, and juice-yield improvement. These alternatives are UV light, high-intensity light pulses, γ-irradiation, pulsed electric fields, radiofrequency electric fields, Ohmic heating, microwave heating, ultrasound, high hydrostatic pressure, supercritical carbon dioxide, ozonation, and flash-vacuum expansion. Although alternatives to heat treatments seem to be less detrimental than the thermal treatment, there are many parameters and conditions that influence the output, as well as the nature of the juice itself, hampering comparisons between different studies. Additionally, future research should focus on understanding the mechanisms underlying the changes in the overall quality of fruit juices, and also on scaled-up processes, process design, and optimization that need to be deal with in detail to maximize their potential as alternative nonthermal technologies in fruit-juice processing while maintaining fruit-juice attributes to the maximum.
This review describes the olive oil production process to obtain extra virgin olive oil (EVOO) enriched in polyphenol and byproducts generated as sources of antioxidants. EVOO is obtained exclusively ...by mechanical and physical processes including collecting, washing, and crushing of olives, malaxation of olive paste, centrifugation, storage, and filtration. The effect of each step is discussed to minimize losses of polyphenols from large quantities of wastes. Phenolic compounds including phenolic acids, alcohols, secoiridoids, lignans, and flavonoids are characterized in olive oil mill wastewater, olive pomace, storage byproducts, and filter cake. Different industrial pilot plant processes are developed to recover phenolic compounds from olive oil byproducts with antioxidant and bioactive properties. The technological information compiled in this review will help olive oil producers to improve EVOO quality and establish new processes to obtain valuable extracts enriched in polyphenols from byproducts with food ingredient applications.
Previous findings on the capacity of Hibiscus sabdariffa (HS) polyphenols to ameliorate metabolic disturbances justify the necessity of studies oriented to find the potential metabolites responsible ...for such an effect. The present study examined the intestinal epithelial membrane permeability of polyphenols present in a phenolic-enriched Hibiscus sabdariffa extract (PEHS), free and encapsulated, using the Caco-2 cell line. Additionally, selected polyphenols (quercetin, quercetin-3-glucoside, quercetin-3-glucuronide, and N-feruloyltyramine) were also studied in the same absorption model. The powerful analytical platform used ultra-high-performance liquid chromatography coupled with ultra-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-ESI-UHR-Qq-TOF-MS), and enabled the characterization of seven new compounds in PEHS. In the permeation study, only a few compounds were able to cross the cell monolayer and the permeability was lower when the extract was in an encapsulated form. Pure compounds showed a moderate absorption in all cases. Nevertheless, these preliminary results may need further research to understand the complete absorption mechanism of Hibiscus polyphenols.
Looking for a strategy to authenticate the declared origin of commercial extra virgin olive oils (EVOOs), 126 samples from six different Mediterranean geographical indications (GIs) are analyzed by ...means of two different platforms LC‐ESI‐QTOF MS (in positive and negative polarity) and GC‐APCI‐QTOF MS (in positive mode) combined to chemometrics. The sample treatment and chromatographic/detection conditions (in both platforms) are chosen to enable the comprehensive characterization of the complete minor fraction of the oils within a single run. Noticeable discrimination among the six evaluated GIs Priego de Córdoba and Baena (Spain), Kalamata (Greece), Toscano (Italy), and Ouazzane and Meknès (Morocco) is achieved building two‐class PLS‐DA models which consider the data coming from both platforms. The contribution of a few thousand molecular features to the statistical models is evaluated in depth and several compounds are pointed out as possible origin markers, describing characteristic compositional patterns for each GI in the evaluated crop year. The complementarity of the different analytical approaches is discussed and diverse strategies are used to identify the classifiers.
Practical Applications: Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI) labels are important tools to promote high quality EVOOs, assuring the connection to a particular territory and the characteristic combination of natural and human factors which make possible to obtain unique oils. In this context, it is imperative to furnish the control labs with innovative tools and methods which are able to provide extensive information about the EVOOs’ minor fraction (of unquestionable importance regarding its overall quality) in just one run and to give the chance to find and identify (and validate) origin markers. The utility of validated classifiers to authenticate the belonging (or not) of an EVOO to a particular GI is clear. The consumers’ confidence can be perceptibly undermined if the geographical name is used on products not having the expected qualities or if the production specifications are sometimes not followed by producers.
The capability of LC‐MS and GC‐MS multi‐class methods to discriminate virgin olive oils from different geographical indications (crop season 2016‐2017) and to identify potential origin markers is demonstrated.
The capability of LC‐MS and GC‐MS multi‐class methods to discriminate virgin olive oils from different geographical indications (crop season 2016‐2017) and to identify potential origin markers is demonstrated.
PDF
