HPLC-UV Polyphenolic Profiles in the Classification of Olive Oils and Other Vegetable Oils via Principal Component Analysis

Revolutionizing Phenolic Content Determination in Vegetable Oils: A Cutting-Edge Approach Using Smartphone-Based Image Analysis

This study addressed the need for a more accessible and efficient method of analyzing phenolic content in vegetable oils. The research aimed to develop a method that could be widely adopted by both researchers and industry professionals, ultimately revolutionizing the way phenolic content in vegetable oils is analyzed. This study developed a method of determining the total phenolic content (TPC) in vegetable oils using smartphone image analysis in the RGB color model. The method employed a gallic acid calibration solution and demonstrated exceptional determination coefficients for the RGB colors. The R-red color was selected as the basis for the analyses, and the method was statistically equivalent to standard UV/Vis spectrophotometry. The highest TPC was determined in hemp and olive oils, while the lowest was found in rice bran, grapeseed, and macadamia nut oils. This study concluded that smartphone image analysis, mainly using the R component of the RGB color model, was a superior alternative to traditional spectrophotometric methods for determining the TPC in vegetable oils. This innovative approach could revolutionize phenolic content analysis by providing researchers and industry professionals with a cost-effective, safe, and efficient tool. The estimated limit of detection (LOD) of 1.254 mg L-1 and limit of quantification (LOQ) of 3.801 mg L-1 further confirmed the reliability and comparability of the method. With these findings, it was expected that the method would be widely adopted in the future.

Investigation of Health Effects of Major Phenolic Compounds in Foods: Extraction Processes, Analytical Approaches and Applications

The escalating costs of healthcare services and a growing awareness of personal health responsibilities have led individuals to explore natural methods alongside conventional medicines for health improvement and disease prevention. The aging global population is experiencing increased health needs, notably related to conditions like diabetes, heart disease, and hypertension. Lifestyle-related diseases, poor dietary habits, and sedentary lifestyles underscore the importance of foods containing nutrients that can aid in preventing and managing these diseases. Phenolic compounds, a fundamental group of phytochemicals, are prominent in the chemical diversity of the natural world and are abundant in functional foods. Widely distributed in various plant parts, these compounds exhibit important functional and sensory properties, including color, taste, and aroma. Their diverse functionalities, particularly antioxidant activity, play a crucial role in mitigating cellular oxidative stress, potentially reducing damage associated with serious health issues such as cardiovascular disease, neurodegenerative disea23ses, and cancer. Phenolic compounds exist in different forms, some combined with glycosides, impacting their biological effects and absorption. Approximately 8000 polyphenols isolated from plants offer significant potential for natural medicines and nutritional supplements. Therefore, their extraction process and selective and sensitive food determination are very important. This review focuses on the extraction processes, analytical methods, and health effects of major phenolic compounds in foods. The examination encompasses a comprehensive analysis of analytical approaches and their applications in elucidating the presence and impact of these compounds on human health.

Comparative Study on the Effect of Phenolics and Their Antioxidant Potential of Freeze-Dried Australian Beach-Cast Seaweed Species upon Different Extraction Methodologies

Brown seaweed is rich in phenolic compounds and has established health benefits. However, the phenolics present in Australian beach-cast seaweed are still unclear. This study investigated the effect of ultrasonication and conventional methodologies using four different solvents on free and bound phenolics of freeze-dried brown seaweed species obtained from the southeast Australian shoreline. The phenolic content and their antioxidant potential were determined using in vitro assays followed by identification and characterization by LC-ESI-QTOF-MS/MS and quantified by HPLC-PDA. The Cystophora sp. displayed high total phenolic content (TPC) and phlorotannin content (FDA) when extracted using 70% ethanol (ultrasonication method). Cystophora sp., also exhibited strong antioxidant potential in various assays, such as DPPH, ABTS, and FRAP in 70% acetone through ultrasonication. TAC is highly correlated to FRAP, ABTS, and RPA (p < 0.05) in both extraction methodologies. LC-ESI-QTOF-MS/MS analysis identified 94 and 104 compounds in ultrasound and conventional methodologies, respectively. HPLC-PDA quantification showed phenolic acids to be higher for samples extracted using the ultrasonication methodology. Our findings could facilitate the development of nutraceuticals, pharmaceuticals, and functional foods from beach-cast seaweed.

A green approach to phenolic compounds recovery from olive mill and winery wastes

The aim of this study was to evaluate the recovery of phenolic compounds from olive mill and winery wastes by conventional solid-liquid extraction (SLE) using water as the extraction solvent. The studied variables were extraction time (5-15 min), temperature (25-90 °C), solid-to-liquid ratio (1:10-1:100 (kg/L)), pH (3-10) and application of multiple extractions (1-3). The extraction efficiency was evaluated in terms of total phenolic content (TPC), determined by high performance liquid chromatography (HPLC-UV), but also from the recovery of some representative phenolic compounds. The optimized conditions were one extraction step, 10 min, 25 °C, 1:30 (kg/L), pH 5 for olive pomace, and one extraction step, 10 min, 70 °C, 1:100 (kg/L), pH 5 for winery residues. The extraction method is simple and suitable for scaling-up in industry, and the aqueous extracts are fully compatible with further purification schemes based on the use of membranes or resins. The optimized technique was applied to a set of different representative residues from olive mill and winery industries, to assess their suitability as sources for phenolic compounds recovery. The phenolic content in the extracts was evaluated by chromatographic analysis and by the Folin-Ciocalteu assay (FC). Furthermore, the antioxidant capacity was determined by 2,2-azinobis-3-etilbenzotiazolina-6-sulfonat (ABTS), 2,-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Because of their high contents in phenolic compounds and great antioxidant capacity, olive pomace and lees filters were identified as especially suited sources for phenolic compounds recovery.

Phenolic Profiling of Berries Waste and Determination of Their Antioxidant Potential

Berries waste is a major issue in Australia’s annual food wastage, which can reach 7.3 million tonnes. This study assessed the phenolic content and antioxidant potential of four fruit berry wastes, including blueberries (Vaccinium corymbosum), blackberries (Rubus spp.), raspberries (Rubus idaeus), and strawberries (Fragaria spp.), followed by their characterization and quantification. Blueberry wastes were high in phenolic content (total phenolic content: 1.97 ± 0.16 mg GAE/gF.W; total flavonoid content: 220.43 ± 13.15 μg QE/gF.W; total tannins content: 16.47 ± 0.98 μg CE/gF.W), and antioxidant potentials are 2,2′-diphenyl-1-picrylhydrazyl: 2.23 ± 0.17 mg AAE/gF.W; 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid): 1.79 ± 0.09 mg AAE/gF.W; ferric reducing antioxidant power: 68.71 ± 11.11 μg AAE/gF.W (total antioxidant capacity: 1.22 ± 0.03 mg AAE/gF.W). The LC-ESI-QTOF-MS/MS analysis identified 87 compounds from blueberry (57), strawberry (40), raspberry (47), and blackberry wastes (27). Indicated by HPLC quantification, blueberry wastes had higher levels of phenolic acid (syringic acid and coumaric acid) and flavonoid (kaempferol and kaempfero l-3-glucoside). Our study reported that phenolics from berry wastes could be utilized in different food, feed, pharmaceutical, and nutraceutical industries.

Spatial Distribution of Polyphenolic Compounds in Corn Grains (Zea mays L. var. Pioneer) Studied by Laser Confocal Microscopy and High-Resolution Mass Spectrometry

Desirable changes in the biochemical composition of food plants is a key outcome of breeding strategies. The subsequent localization of nutritional phytochemicals in plant tissues gives important information regarding the extent of their synthesis across a tissue. We performed a detailed metabolomic analysis of phytochemical substances of grains from Zea mays L. (var. Pioneer) by tandem mass spectrometry and localization by confocal microscopy. We found that anthocyanins are located mainly in the aleurone layer of the grain. High-performance liquid chromatography in combination with ion trap tandem mass spectrometry revealed the presence of 56 compounds, including 30 polyphenols. This method allows for effective and rapid analysis of anthocyanins by plotting their distribution in seeds and grains of different plants. This approach will permit a more efficient screening of phenotypic varieties during food plant breeding.

Rapid and Simultaneous Determination of Free Aromatic Carboxylic Acids and Phenols in Commercial Juices by GC-MS after Ethyl Chloroformate Derivatization

Natural phenol and phenolic acids are widely distributed in the plant kingdom and the major dietary sources include fruits and beverages derived therefrom. Over the past decades, these compounds have been widely investigated for their beneficial effects on human health and, at the same time, several analytical methods have been developed for their determination in these matrices. In the present paper, 19 different aromatic carboxylic acids and phenols were characterized by GC-MS using ethyl chloroformate as the derivatizing agent. This procedure occurs quickly at room temperature and takes place in aqueous media simultaneously with the extraction step in the presence of ethanol using pyridine as a catalyst. The analytical method herein developed and validated presents excellent linearity in a wide concentration range (25–3000 ng/mL), low LOQ (in the range 25–100 ng/mL) and LOD (in the range 12.5–50 ng/mL), and good accuracy and precision. As a proof of concept, ethyl chloroformate derivatization was successfully applied to the analysis of a selection of commercial fruit juices (berries, grape, apple, pomegranate) particularly rich in phenolic compounds. Some of these juices are made up of a single fruit, whereas others are blends of several fruits. Our results show that among the juices analyzed, those containing cranberry have a total concentration of the free aromatic carboxylic acids and phenols tested up to 15 times higher than other juices.

Date Palm Seed Oil (Phoenix dactylifera L.) Green Extraction: Physicochemical Properties, Antioxidant Activities, and Phenolic and Fatty Acid Profiles

Date palm seed oil is among the precious vegetable oils with low yield, whose extraction is commonly done with organic solvents which cause serious problems. This study aims to assess the effectiveness of orange peel essential oil as biosolvent for date seed oil extraction. Green extraction was conducted by Soxhlet apparatus as well as by soaking and compared with the Soxhlet method using petroleum ether. The GC-MS analysis of orange peel essential oil confirmed its richness with limonene (94.31%), which justifies its usefulness as green solvent. The latter gave higher yields, the extracted bio-oil was light brown with pleasant odor, and the characteristics were consistent with international standards. Based on the GC profiles, obtained oils were similar using both solvents, and the major compounds were oleic and lauric acids. The bio-oil phenolic content and the antioxidant activity were high, and the major compounds were the protocatechuic, chlorogenic, and 4-O-caffeoylquinic acids. Gallic and $p$ -coumaric acids were the major compounds for oil extracted by petroleum ether.

Olive Pomace Phenolic Compounds Stability and Safety Evaluation: From Raw Material to Future Ophthalmic Applications

Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive's industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO₂ extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested.

Instrumental Techniques to Classify Olive Oils according to Their Quality

This review includes an update of the publications on quality classification of olive oils into extra, virgin or lampante olive oil categories. Nowadays, the official method to carry out this classification is time-consuming and, sometimes, it is not systematic and/or objective. It is based on conventional physicochemical analysis and on a sensorial tasting of olive oils carried out by a panel of experts. The aim of this review was to explore and give value to the alternative techniques reported in the bibliography to complement the current official methods established for that classification of olive oils. Specifically considered were non-separation and separation analytical techniques which could contribute to correctly classify olive oils according to their physicochemical and/or sensorial characteristics. An in-depth description has been written on the methods used to differentiate these three types of olive oils and the main advantages and disadvantages of the proposed procedures. The techniques here reviewed could be a real and fast option to complement or even substitute some of the analysis included in the official method. Finally, general trends and detected difficulties found to address this issue have been discussed throughout the article.

Screening of Phenolic Compounds in Australian Grown Berries by LC-ESI-QTOF-MS/MS and Determination of Their Antioxidant Potential

Berries are grown worldwide with the most consumed berries being blackberries (Rubus spp.), blueberries (Vaccinium corymbosum), red raspberries (Rubus idaeus) and strawberries (Fragaria spp.). Berries are either consumed fresh, frozen, or processed into wines, juices, and jams. In recent times, researchers have focused their attention on berries due to their abundance in phenolic compounds. The current study aimed to evaluate the phenolic content and their antioxidant potential followed by characterization and quantification using LC-ESI-QTOF-MS/MS and HPLC-PDA. Blueberries were highest in TPC (2.93 ± 0.07 mg GAE/gf.w.) and TFC (70.31 ± 1.21 µg QE/gf.w.), whereas the blackberries had the highest content in TTC (11.32 ± 0.13 mg CE/gf.w.). Blueberries had the highest radical scavenging capacities for the DPPH (1.69 ± 0.09 mg AAE/gf.w.), FRAP (367.43 ± 3.09 µg AAE/gf.w.), TAC (1.47 ± 0.20 mg AAE/gf.w.) and ABTS was highest in strawberries (3.67 ± 0.14 mg AAE/gf.w.). LC-ESI-QTOF-MS/MS study identified a total of 65 compounds including 42 compounds in strawberries, 30 compounds in raspberries, 28 compounds in blueberries and 21 compounds in blackberries. The HPLC-PDA quantification observed phenolic acid (p-hydroxybenzoic) and flavonoid (quercetin-3-rhamnoside) higher in blueberries compared to other berries. Our study showed the presence of phenolic acids and provides information to be utilized as an ingredient in food, pharmaceutical and nutraceutical industries.

Olive Mill and Winery Wastes as Viable Sources of Bioactive Compounds: A Study on Polyphenols Recovery

In this study, the recovery of polyphenols from olive oil mill and winery waste was investigated. The performance of ultrasound assisted extraction (UAE), microwave assisted extraction (MAE), and pressurized liquid extraction (PLE) was assessed using ethanol-water mixtures, which are compatible with food, nutraceutical, and cosmetic applications. The extraction efficiency from olive pomace and lees samples was evaluated in terms of total polyphenol content (TPC), determined by high performance liquid chromatography (HPLC) and Folin-Ciocalteu assay. The effect of solvent composition, temperature, and time was analyzed by response surface methodology. Ethanol:water 50:50 (v/v) was found to be a suitable solvent mixture for both kinds of samples and all three extraction techniques. The performance of the extraction techniques was evaluated, under optimal experimental conditions, with a set of different representative samples of residues from olive oil and wine production. Overall, the best extraction efficiency for olive pomace residues was provided by MAE (ethanol:water 50:50 (v/v), 90 °C, 5 min), and for wine residues by PLE (ethanol:water 50:50 (v/v), 100 °C, 5 min, 1 cycle). However, the results provided by UAE (ethanol:water 50:50 (v/v), 30 min) were also suitable. Considering not only extraction performance, but also investment and operational costs, UAE is proposed for a future scaling up evaluation. Regarding olive pomace as a source for natural phenolic antioxidants, olive variety and climatic conditions should be taken into account, since both influence TPC in the extracts, while for winery residues, lees from red wines are more suitable than those from white wines.

Synthesis and solid-state characterization of diclofenac imidazolium monohydrate: an imidazolium pharmaceutical ionic liquid

A new imidazolium hydrated salt (DCF–IMI–H₂O) of the nonsteroidal anti-inflammatory drug diclofenac (DCF) was synthesized by solvent evaporation.

LC-ESI-QTOF/MS Profiling of Australian Mango Peel By-Product Polyphenols and Their Potential Antioxidant Activities

Mango (Mangifera indica L.) is one of the most important fruits in the world. Mango peel is an important by-product that is rich in polyphenols and it could have high economic value if it is effectively utilized. Phenolic characterization is an essential step in the commercial utilization of mango peel by-products as food ingredients. Herein, qualitative and quantitative analyses of two Australian mango peel “Keitt” and “Kensington Pride” (K&P) by-products were conducted while using liquid chromatography coupled to electrospray ionisation and quadrupole time of flight mass spectrometry (LC-ESI-QTOF/MS) and high-performance liquid chromatography coupled to photodiode array detector (HPLC-PDA). A total of 98 polyphenols compounds were tentatively identified in both Keitt peel and K&P peel extracts, with greater concentrations of these compounds being detected in Keitt peel. The total phenolic content (TPC), total flavonoid content (TFC), and a total tannin content (TTC) were determined. The antioxidant activity of mango peel by-products was determined while using 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assay, ferric reducing antioxidant power (FRAP) assay, and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assay. Keitt peel contained higher concentrations of total phenolic compounds, flavonoids, and tannins and had higher antioxidant capacity in DPPH, FRAP, and ABTS assays as compared to K&P peel. In HPLC-PDA quantification, the predominant phenolic compounds in Keitt peel and K&P peel were catechin (62.32 ± 0.01 mg/gd.w.) and syringic acid (17.78 ± 0.01 mg/gd.w).

LC-ESI-QTOF/MS Characterization of Phenolic Compounds in Palm Fruits (Jelly and Fishtail Palm) and Their Potential Antioxidant Activities

Palm fruits have gained growing attention for their nutrition values and health promotion perspectives. They have a diverse range of bioactive compounds including carotenoids, vitamins, dietary fibres and especially polyphenolic compounds. These polyphenolic compounds contribute to the putative health benefits of palm fruits. Nevertheless, the detailed information about these polyphenols in palm fruits is limited. The present work was conducted to comprehensively characterize polyphenols in two palm fruits, jelly palm (Butia ordorata) and fishtail palm (Caryota uren), using liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS) and assess their antioxidant potential. The total phenolic content (TPC), total tannins content (TTC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assay and 2,2′-azinobis-(3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS) scavenging abilities and ferric reducing antioxidant power (FRAP) were higher in the jelly palm fruit while total flavonoid contents (TFC) were higher in the fishtail palm. The LC-ESI-QTOF/MS tentatively identified a total of 86 phenolic compounds in both jelly and fishtail palm fruits. Although both palm fruits exhibited different phenolic profiles, hydroxycinnamic acids and flavonols were the most common in both. In high performance liquid chromatography photodiode array (HPLC-PDA) quantification, 4-hydroxybenzoic acid (317.46 ± 4.68 µg/g) and catechin (4724.00 ± 32.39 µg/g) were the most abundant phenolic acid and flavonoid quantified in the jelly palm fruit, respectively. Quercetin (557.28 ± 7.81 µg/g) and kaempferol 3-O-glucoside (220.99 ± 2.06 µg/g) were the most abundant flavonoids quantified in the fishtail palm. Our study indicates that palm fruit is a good source of polyphenols and has strong antioxidant potential for health promotion. Furthermore, this study provides the scientific basis for an exploitation of jelly and fishtail palm fruits in the food, pharmaceutical and nutraceutical industries.

Characterization of Phenolic Compounds and Their Contribution to Sensory Properties of Olive Oil

Olive oil is not only known for its pungent, bitter, and fruity taste, but also for its health potential, which is often hypothesized to depend on its phenolic compounds. One hundred extra virgin olive oil samples (monocultivaric as well as blends of varieties) were assessed with regard to their sensory properties and phenolic compound composition. Nineteen phenolic compounds have been determined and correlated with sensory data. In all olive oil samples, oleocanthal and oleacein were the most abundant phenolic compounds, with average amounts of 77.9 mg/kg and 41.8 mg/kg, respectively. The highest correlation coefficient between a sensory descriptor and the phenolic compounds was found for the bitter taste sensation and the total phenolic content with r = 0.72 and in particular, for 3,4-DHPEA-EA, with r = 0.57. Intensity plots were assessed for the three main sensory descriptors fruitiness, bitterness, pungency, and for the quality factor harmony, which is associated with the degree of ripeness aroma of olive oil. Positive correlations for the aroma descriptors freshly cut grass, leaves, and nuts, and the phenolic compounds were especially observed for oleoside 11-methylester and vanillic acid. The present study provides a comprehensive database of phenolic compounds in olive oils from six different varieties and seven countries.

Determination of HPLC-UV Fingerprints of Spanish Paprika (Capsicum annuum L.) for Its Classification by Linear Discriminant Analysis

The development of a simple HPLC-UV method towards the evaluation of Spanish paprika's phenolic profile and their discrimination based on the former is reported herein. The approach is based on C18 reversed-phase chromatography to generate characteristic fingerprints, in combination with linear discriminant analysis (LDA) to achieve their classification. To this aim, chromatographic conditions were optimized so as to achieve the separation of major phenolic compounds already identified in paprika. Paprika samples were subjected to a sample extraction stage by sonication and centrifugation; extracting procedure and conditions were optimized to maximize the generation of enough discriminant fingerprints. Finally, chromatograms were baseline corrected, compressed employing fast Fourier transform (FFT), and then analyzed by means of principal component analysis (PCA) and LDA to carry out the classification of paprika samples. Under the developed procedure, a total of 96 paprika samples were analyzed, achieving a classification rate of 100% for the test subset (n = 25).

Characterization and classification of Spanish paprika (Capsicum annuum L.) by liquid chromatography coupled to electrochemical detection with screen-printed carbon-based nanomaterials electrodes

Screen-printed electrodes based on graphite, carbon nanotubes, carbon nanofibers, and graphene were tested as amperometric detectors for the determination of phenolic compounds by high performance liquid chromatography (HPLC). The chromatographic performance as well as the obtained sensitivity, detection and quantification limits suggest that carbon nanofibers modified screen-printed electrode (SPCE-CNF) is the amperometric sensor that provides the best analytical performance. Upon this confirmation, chromatographic data obtained using SPCE-CNF were exploited by means of linear discriminant analysis (LDA) to successfully characterize and classify 96 Spanish paprika (Capsicum annuum L.) samples with different origin and type: from La Vera (including sweet, bittersweet and spicy types) and from Murcia (including sweet and spicy types).

Authentication and Quantitation of Fraud in Extra Virgin Olive Oils Based on HPLC-UV Fingerprinting and Multivariate Calibration

High performance liquid chromatography method with ultra-violet detection (HPLC-UV) fingerprinting was applied for the analysis and characterization of olive oils, and was performed using a Zorbax Eclipse XDB-C8 reversed-phase column under gradient elution, employing 0.1% formic acid aqueous solution and methanol as mobile phase. More than 130 edible oils, including monovarietal extra-virgin olive oils (EVOOs) and other vegetable oils, were analyzed. Principal component analysis results showed a noticeable discrimination between olive oils and other vegetable oils using raw HPLC-UV chromatographic profiles as data descriptors. However, selected HPLC-UV chromatographic time-window segments were necessary to achieve discrimination among monovarietal EVOOs. Partial least square (PLS) regression was employed to tackle olive oil authentication of Arbequina EVOO adulterated with Picual EVOO, a refined olive oil, and sunflower oil. Highly satisfactory results were obtained after PLS analysis, with overall errors in the quantitation of adulteration in the Arbequina EVOO (minimum 2.5% adulterant) below 2.9%.