Use of polyphenolic fingerprints established by comprehensive two-dimensional liquid chromatography for the classification of honeys according to their floral origin.

In this work, the polyphenolic composition of honeys from three different floral origins (chestnut, heather, and thyme), coming from different geographical areas of Spain was investigated. First, samples were characterized in terms of total phenolic content (TPC) and antioxidant capacity, which was established by three different assays. The results revealed that the studied honeys presented similar TPCs and antioxidant capacities, with a wide variability within each floral origin. Next, a comprehensive two-dimensional liquid chromatography method was developed for the first time to establish polyphenol fingerprints of the three types of honeys, after optimizing the separation in terms of column combination and mobile phase gradient programs. After that, the detected common peaks were used for the construction of a linear discriminant analysis (LDA) model able to discriminate honeys according to their floral origin. The LDA model obtained was adequate for the classification of the floral origin of the honeys based on polyphenolic fingerprint data.

Galactose-functionalized methacrylate polymers as affinity sorbents for extraction of food allergen lectins.

In this study, glycidyl methacrylate (GMA)-based materials functionalized with different galactose derivatives were prepared to be used as affinity sorbents for solid-phase extraction (SPE) of several food allergen lectins (such as phytohemagglutinin (PHA)). First, GMA-based polymers were synthesized and then galactose derivatives were immobilized onto the GMA surface using two different synthetic routes. In the first approach, the bare polymer was modified with ethylenediamine and glutaraldehyde, and subsequently two galactose derivatives were immobilized. In the second strategy, the starting polymer was modified with cystamine and gold nanoparticles (AuNPs), on which a thiolated galactose derivative was subsequently anchored. The resulting materials were characterized by scanning electron microscopy and used as SPE sorbents for the isolation of PHA (as probe protein) from food matrices. Different SPE parameters (sample pH, eluent solution composition, binding capacity, sample volume, selectivity and reusability) were evaluated. The material that provided the best PHA recovery (98%) was the one obtained in the second approach, being this material successfully applied to the selective extraction of PHA and other similar lectins from different foods (red and lima dried beans, fresh soybeans and biscuits containing soybean protein traces as indicated in their label). After SDS-PAGE of eluates, all samples only exhibited the characteristic PHA band around 30 kDa, suggesting the high potential of the developed material for application in food allergy field.

Skin absorption of inorganic nanoparticles and their toxicity: A review.

The role of inorganic nanoparticles in our society is increasing every day, from its use in sunscreens to their introduction in analytical laboratories, pharmacy, medicine, agricultural and other uses. Therefore, in order to establish precautions as well as correct handling of this type of material by operators, it is important to determine the ability of these compounds to travel through the different layers of the skin and to study their possible toxicological effects. In this sense, several authors have studied the ability of inorganic nanoparticles to penetrate the skin barrier by diverse methodologies in in vivo and in vitro modes. In the first case, most of the studies have been performed with animal skins that can imitate the human one (porcine, mouse and guinea pigs, among others), although human skin from surgery have been also explored. However, the use of animals is a common model that should be avoided in the following years due to ethical issues. In this sense, the use of in vitro methodologies is also usually selected to study the dermal absorption of nanoparticles through the skin. Nevertheless, most of the studies are performed with authentic animal skins, instead of the use of synthetic skins that imitate the permeability of our skin system, which has been scarcely studied. In addition, most of the literature is focused in achieving high-transdermal uptake to use nanoparticles (not only inorganic) as carriers for drugs, but little efforts have been done in the study of their inherent percutaneous absorption and toxicity. For these reasons, this review covers the current state-of-the-art of dermal absorption of inorganic nanoparticles in skin and their possible toxicity taking into account that people can be in contact with these nanomaterials in daily life, work or other places. In this sense, the observed results showed that the nanoparticles rarely reach the blood circulatory system, and no big toxicological effects were commonly found when in vivo and actual skin was used. In addition, similar results were found when synthetic skins were used, demonstrating the possibility of avoiding animals in these studies. In any case, more studies covering the dermal absorption of nanoparticles should be performed to have a better understanding of how nanoparticles can affect our health.

Reticular framework materials in miniaturized and emerging formats in analytical chemistry.

In recent years, important efforts have been put into miniaturization, coming on the scene formats such as chips, 3D-printed objects and paper-based devices. These systems have been applied to biological and chemical processes taking profit of their advantages such as waste reduction, low cost, portability, etc. Despite their benefits, there is a need to continue developing easier-to-use devices with enhanced performance addressed to face the current analytical challenges. In this sense, reticular porous materials such as metal- (MOFs) and covalent- (COFs) organic frameworks with unique features including tailorable porous architectures and tunable chemistry have attracted a lot of attention in various fields. Nevertheless, the combination of these materials with miniaturized and emerging formats has been scarcely investigated. This review is intended to bridge this gap and highlight the recent contributions of these materials in these analytical formats. Thus, this work aims to provide a comprehensive review of the field, highlighting incorporation strategies into the functional supports available to date, and the applications of the resulting systems in both off-site laboratory studies (mostly dedicated to (micro)extraction purposes) and on-site analysis. Finally, a discussion of challenges and future directions in this field is also given.

Automatic and non-targeted analysis of the volatile profile of natural and alkalized cocoa powders using SBSE-GC-MS and chemometrics.

A total of 56 key volatile compounds present in natural and alkalized cocoa powders have been rapidly evaluated using a non-target approach using stir bar sorptive extraction gas chromatography mass spectrometry (SBSE-GC-MS) coupled to Parallel Factor Analysis 2 (PARAFAC2) automated in PARADISe. Principal component analysis (PCA) explained 80% of the variability of the concentration, in four PCs, which revealed specific groups of volatile characteristics. Partial least squares discriminant analysis (PLS-DA) helped to identify volatile compounds that were correlated to the different degrees of alkalization. Dynamics between compounds such as the acetophenone increasing and toluene and furfural decreasing in medium and strongly alkalized cocoas allowed its differentiation from natural cocoa samples. Thus, the proposed comprehensive analysis is a useful tool for understanding volatiles, e.g., for the quality control of cocoa powders with significant time and costs savings.

Selection and characterization of DNA aptamers for highly selective recognition of the major allergen of olive pollen Ole e 1.

In this study, single-stranded DNA aptamers with binding affinity to Ole e 1, the major allergen of olive pollen, were selected using systematic evolution of ligands by exponential enrichment (SELEX) method. Binding of the aptamers was firstly established by enzyme-linked oligonucleotide assay (ELONA) and aptaprecipitation assays. Additionally, aptamer-modified monolithic capillary chromatography was used in order to evaluate the recognition of this allergenic protein against other non-target proteins. The results indicated that AptOle1#6 was the aptamer that provided the highest affinity for Ole e 1. The selected aptamer showed good selective recognition of this protein, being not able to retain other non-target proteins (HSA, cyt c, and other pollen protein such as Ole e 9). The feasibility of the affinity monolithic column was demonstrated by selective recognition of Ole e 1 in an allergy skin test. The stability and reproducibility of this monolithic column was suitable, with relative standard deviations (RSDs) in retention times and peak area values of 7.8 and 9.3%, respectively (column-to-column reproducibility). This is the first study that describes the design of an efficient DNA aptamer for this relevant allergen.

Determination of antibiotics in meat samples using analytical methodologies: A review.

Antibiotics are widely used to prevent or treat some diseases in human and veterinary medicine and also as animal growth promoters. The presence of these compounds in foods derived from food-producing animals can be a risk for human health. Consequently, regulatory agencies have set maximum residue limits for antibiotics in food samples. Therefore, the development of novel methodologies for its determination in food samples is required. Specifically, the analysis and quantification of these substances in meat tissues is a challenge for the analytical chemistry research community. This is due to the complexity of the matrix and the low detection limits required by the regulatory agencies. In this sense, a comprehensive review on the development of new sample preparation treatments involving extraction, cleanup, and enrichment steps of antibiotics in meat samples in combination with sensitive and sophisticated determination techniques that have been carry out in the last years is necessary. Therefore, the aim of this work is to summarize the published methodologies for the determination of antibiotics from 2016 until the beginning of the second semester of 2020. The first part of this review includes an introduction about antibiotic families, followed by sample preparation and determination techniques applied to the different families. Finally, a detailed discussion of the current trends and the future possible perspectives in this field are also included.

Roadmap of cocoa quality and authenticity control in the industry: A review of conventional and alternative methods.

Cocoa (Theobroma cacao L.) and its derivatives are appreciated for their aroma, color, and healthy properties, and are commodities of high economic value worldwide. Wide ranges of conventional methods have been used for years to guarantee cocoa quality. Recently, however, demand for global cocoa and the requirements of sensory, functional, and safety cocoa attributes have changed. On the one hand, society and health authorities are increasingly demanding new more accurate quality control tests, including not only the analysis of physicochemical and sensory parameters, but also determinations of functional compounds and contaminants (some of which come in trace quantities). On the other hand, increased production forces industries to seek quality control techniques based on fast, nondestructive online methods. Finally, an increase in global cocoa demand and a consequent rise in prices can lead to future cases of fraud. For this reason, new analytes, technologies, and ways to analyze data are being researched, developed, and implemented into research or quality laboratories to control cocoa quality and authenticity. The main advances made in destructive techniques focus on developing new and more sensitive methods such as chromatographic analysis to detect metabolites and contaminants in trace quantities. These methods are used to assess cocoa quality; study new functional properties; control cocoa authenticity; or detect frequent emerging frauds. Regarding nondestructive methods, spectroscopy is the most explored technique, which is conducted within the near infrared range, and also within the medium infrared range to a lesser extent. It is applied mainly in the postharvest stage of cocoa beans to analyze different biochemical parameters or to assess the authenticity of cocoa and its derivatives.

Current trends in affinity-based monoliths in microextraction approaches: A review.

This article reviews the research contributions along the past five years concerning to monolithic materials for the development of affinity-based sorbents in the field of microextraction techniques. The first part of this paper includes an introduction regarding monolithic affinity media and information of different binding agents (such as immunoglobulin-binding proteins, enzymes, lectins, antibodies, aptamers, dyes and immobilized metal ions and nanoparticles, among others) that can act as affinity ligands. Then, the preparation of monoliths and ligand immobilization strategies as well as the different available formats (syringes, pipette tips, spin columns, capillaries, disks and microfluidic devices) for their use in micro-solid phase extraction are mentioned. On the basis of the binding agents used to prepare affinity monolithic-based sorbents, the last part of manuscript includes several analytical and preparative applications of these monoliths for sample preparation covering different fields (analytical chemistry, biotechnology, proteomics, etc.). Current trends and possible future directions of these affinity-based sorbents in sample preparation are also given.

Olive leaf extracts for shelf life extension of salmon burgers.

In this work, the effect of the addition of olive leaf extracts on the quality of vacuum-packed salmon burgers stored at 4 ℃ during 16 days has been studied. Olive leaf extract and its hydrolysate were initially characterized and then incorporated to salmon burgers. A shelf life study was conducted in three different batches (control, olive leaf extract, and hydrolyzed olive leaf extract burgers). Among the chemical indices determined, total volatile base nitrogen values were lower in hydrolyzed olive leaf extract and olive leaf extract burgers than in control samples. Lipid oxidation was lower in salmon burger with olive leaf extract. Salmon mince treated with hydrolyzed olive leaf extract showed lower microbial counts during the whole study, which extended the shelf life of the fish product. Therefore, the potential of olive leaf extracts to preserve salmon burgers during cold storage has been demonstrated.

Proteomic fingerprinting of apple fruit, juice, and cider via combinatorial peptide ligand libraries and MS analysis.

Combinatorial peptide ligand libraries coupled to MS was applied to extensively map the proteome of apple fruit, and to detect its presence in commercial apple juice and cider to evaluate their authenticity and genuineness. Using the Uniprot_Malus database, 96 proteins were detected in apples, among which 30 proteins were specifically captured via combinatorial peptide ligand libraries. Next, three proteins, previously recognized in fruits, were found in apple juice, which were involved in cellular metabolism of fruit maturation and in allergenic reactions. On the other hand, only one Malus allergen was identified in cider beads eluate, demonstrating that the industrial processes did not prevent any negative effects in sensitive subjects. Thus, the present study not only increases the knowledge of the apple proteome but also offers a reliable analytical method to assess quality and genuineness of commercial products, which could be also used to inform consumers about the presence of allergens.

Characterization of Spanish powdered seaweeds: Composition, antioxidant capacity and technological properties.

This work aimed to characterise four seaweed species: nori (Phorphyra), kombu (Laminaria), wakame (Undaria) and sea spaghetti (Himanthalia elongata). Their nutritional composition, total phenolic compounds (TPC), antioxidant capacity, oil and water holding capacity (OHC and WHC), and swelling capacity (SC) were determined. Wakame and nori exhibited the highest proteins contents, rich in essential amino acids and in those related to umami flavour. All the samples had a low lipid content and high ash content values. High fibre levels were observed, especially in kombu. The TPC content and antioxidant capacity of sea spaghetti was significantly higher than in the other samples. The OHC, WHC and SC of the seaweeds demonstrated their potential influence on texture of food products. The incorporation of these seaweeds into different foodstuffs could entail an improvement of the nutritional quality and texture properties, and could also reduce the use of Na and synthetic additives.

Proteomic fingerprinting of mistletoe (Viscum album L.) via combinatorial peptide ligand libraries and mass spectrometry analysis.

Combinatorial peptide ligand libraries (CPLLs), coupled to mass spectrometry (MS) analysis, have been used to investigate in depth the proteome of Viscum album L. (VA), commonly named European mistletoe, in order to provide a first proteomic fingerprinting. For this purpose, the proteins were captured via CPLLs at two different pH values (acidic and neutral). A total of 648 non-redundant proteins were identified by using two different databases. The two pH values, chosen for bead incubations, have contributed to increment the capture ability: 56% and 31% of CPLLs species were respectively recognized at pH7.2 and at pH2.2. Finally the biological function of identified proteins was evaluated in order to understand their role on human health and the potential benefits of mistletoe extracts in medicine. SIGNIFICANCE: Viscum album L. (VA) extracts are recently used as supporting medicine for cancer therapy, improving patients' survival and increasing their quality of life in medicine. These anticancer effects are investigated and they are probably due to mistletoe's capability to favor tumor cell's death and to modulate the immune system. Although the increasing interest in VA medical benefits, the role of its components in human health remains unclear. In order to exploit this aspect, it is important to comprehensively study proteins present in Viscum album L. (VA) extracts. Nevertheless, since plant proteomics analysis is in most cases handicapped by the presence of high-abundance proteins masking the detection of the low-abundance ones, it is important to overcome this challenge. In this sense, combinatorial peptide ligand libraries (CPLLs) have been used to reduce the dynamic protein concentration range to enable the identification of a higher amount of proteins than employing conventional methods. In this work, a total of 648 non-redundant proteins were identified: 56% and 31% of CPLLs species were respectively recognized at pH7.2 and at pH2.2. This deep proteome identification was useful to investigate the biological functions of proteins in order to evaluate their potential role in human health.

Solid-phase extraction based on ground methacrylate monolith modified with gold nanoparticles for isolation of proteins.

In this study, a novel polymeric material functionalized with gold nanoparticles (AuNPs) was prepared as solid-phase extraction (SPE) sorbent for isolation of proteins. The sorbent was synthesized from a powdered poly(glycidyl-co-ethylene dimethacrylate) monolith, and modified with ammonia, followed by immobilization of AuNPs on the pore surface of the material. To evaluate the performance of this SPE support, proteins were selected as test solutes, being the extraction conditions and other parameters (loading capacity and regenerative ability of sorbent) established. The results indicated that this sorbent could be employed to selectively capture proteins according to their pI, on the basis of the strong affinity of these biomacromolecules towards to AuNPs surface. The applicability of this sorbent was demonstrated by isolating protein species of interest (bovine serum albumin, cytochrome c and lectins in European mistletoe leaves), followed by SDS-PAGE analysis.

Orange proteomic fingerprinting: From fruit to commercial juices.

Combinatorial peptide ligand library technology, coupled to mass spectrometry, has been applied to extensively map the proteome of orange pulp and peel and, via this fingerprinting, to detect its presence in commercial orange juices and drinks. The native and denaturing extraction protocols have captured 1109 orange proteins, as identified by LC-MS/MS. This proteomic map has been searched in an orange concentrate, from a Spanish juice manufacturer, as well as in commercial orange juices and soft drinks. The presence of numerous orange proteins in commercial juices has demonstrated the genuineness of these products, prepared by using orange fruits as original ingredients. However, the low number of identified proteins in sparkling beverages has suggested that they were prepared with scarce amounts of fruit extract, thus imparting lower quality to the final products. These findings not only increase the knowledge of the orange proteome but also present a reliable analytical method to assess quality and genuineness of commercial products.

Quality control of fruit juices by using organic acids determined by capillary zone electrophoresis with poly(vinyl alcohol)-coated bubble cell capillaries.

An enhanced method for the determination of organic acids in several fruit juices by capillary zone electrophoresis (CZE) with direct UV-Vis detection has been developed in this work. First, a study with simulated real juice samples was done to find the best separation conditions. Next, several commercial fruit juices were analyzed, and the organic acid contents were quantified in less than 12 min using a poly(vinyl alcohol)-coated fused-silica 'bubble cell' capillary. The present method is reliable, fast and provides detection limits comprised between 0.1 and 2.5 µg mL(-1). Moreover, different chemometric techniques, based on CZE data, were examined. Linear discriminant analysis allowed the differentiation of fruit juices according to the fruit type, whereas multiple linear regression models predicted the percentages of orange and pineapple juices in binary blends with grape. Thus, the present methodology is of utmost interest for routine and quality control purposes in food industries.

Rapid differentiation of commercial juices and blends by using sugar profiles obtained by capillary zone electrophoresis with indirect UV detection.

A method for the determination of sugars in several fruit juices and nectars by capillary zone electrophoresis with indirect UV-vis detection has been developed. Under optimal conditions, commercial fruit juices and nectars from several fruits were analyzed, and the sugar and cyclamate contents were quantified in less than 6 min. A study for the detection of blends of high-value juices (orange and pineapple) with cheaper alternatives was also developed. For this purpose, different chemometric techniques, based on sugar content ratios, were applied. Linear discriminant analysis showed that fruit juices can be distinguished according to the fruit type, juice blends also being differentiated. Multiple linear regression models were also constructed to predict the adulteration of orange and pineapple juices with grape juice. This simple and reliable methodology provides a rapid analysis of fruit juices of economic importance, which is relevant for quality control purposes in food industries and regulatory agencies.

Efficient extraction of olive pulp and stone proteins by using an enzyme-assisted method.

An efficient protein extraction protocol for proteins from olive pulp and stone by using enzymes was developed. For this purpose, different parameters that affect the extraction process, such as enzyme type and content, pH, and extraction temperature and time, were tested. The influence of these factors on protein recovery was examined using the standard Bradford assay, while the extracted proteins were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The best extraction conditions were achieved at pH 7.0 and 5% (v/v) Palatase® 20000 L (lipase) for pulp and Lecitase® Ultra (phospholipase) for stone proteins. The optimal extraction temperature and time were 30 and 40 °C for 15 min for pulp and stone tissues, respectively. Under these conditions, several protein extracts coming from olive fruits of different genetic variety were analyzed, their profiles being compared by SDS-PAGE. The developed enzyme-assisted extraction method showed faster extraction, higher recovery, and reduced solvent usage than the nonenzymatic methods previously described in the literature. In the case of stone proteins, different electrophoretic profiles and band intensities were obtained that could be helpful to distinguish samples according to their genetic variety.

According to the CPLL proteome sheriffs, not all aperitifs are created equal!

Combinatorial peptide ligand libraries (CPLLs) have been adopted for investigating the proteome of a popular aperitif in Northern Italy, called "Amaro Branzi", stated to be an infusion of a secret herbal mixture, of which some ingredients are declared on the label, namely Angelica officinalis, Gentiana lutea and orange peel, sweetened by a final addition of honey. In order to assess the genuineness of this commercial liqueur, we have prepared extracts of the three vegetable ingredients, assessed their proteomes, and compared them to the one found in the aperitif. The amaro's proteome was identified via prior capture with CPLLs at two different pH values (2.2 and 4.8). Via mass spectrometry analysis of the recovered fractions, after elution of the captured populations in 4% boiling SDS, we could confirm the presence of the following: six proteins originating from honey, 11 from orange peels, 29 from G. lutea and 46 from A. officinalis (including shared species), plus 33 species which could not be attributed to the other secret ingredients, due to paucity of genomic data on plant proteins, for a total of 93 unique gene products (merging shared proteins). This fully confirmed the genuineness of the product. Considering that most of these species could be present in trace amounts, undetectable by conventional techniques, the CPLL methodology, due to its ability to enhance the signal of trace components up to 3 to 4 orders of magnitude, could represent a powerful tool for investigating the genuineness and natural origin of commercial beverages in order to protect consumers from adulterated products.

Tannin analysis of chestnut bark samples (Castanea sativa Mill.) by HPLC-DAD-MS.

In the present investigation, an HPLC-DAD/ESI-MS method for the complete analysis of tannins and other phenolic compounds of different commercial chestnut bark samples was developed. A total of seven compounds (vescalin, castalin, gallic acid, vescalagin, 1-O-galloyl castalagin, castalagin and ellagic acid) were separated and quantified, being 1-O-galloyl castalagin tentatively identified and found for the first time in chestnut bark samples. Thus, this method provided information regarding the composition and quality of chestnut bark samples, which is required since these samples are commercialised due to their biochemical properties as ingredients of food supplements.