Determination of amino acids in pomegranate juices and fingerprint for adulteration with apple juices

A volatilomics analytical protocol employing solid phase microextraction coupled to GC × GC-MS analysis and combined with multivariate chemometrics for the detection of pomegranate juice adulteration

In this work, a solid-phase microextraction (SPME) method combined with two-dimensional gas chromatography coupled to mass spectrometry (GC × GC-MS) was optimized and used to assess the authenticity of pomegranate juice to prevent fraudulent practices. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for the extraction of the volatiles. The critical parameters that affect the extraction process, such as the sample volume, and the extraction time were studied. The optimized protocol involved the addition of 15 mL of juice in 50 mL vial and saturation with 30% w/v NaCl.The extraction was carried out within 45 min under 1000 rpm stirring and was applied in the analysis of real juice samples to assess authenticity and detect low levels of pomegranate juice adulteration with grape and apple juice down to 1%. Commercially available pomegranate juice samples were acquired (n1 = 6) and adulterated with 1% of apple juice (n2 = 6), 1% of grape juice (n3 = 6), and a mixture of 1% apple juice and 1% grape juice (n4 = 6). Authentic pomegranate juice samples and adulterated mixtures were analyzed by SPME-GC × GC-MS. The analysis resulted in the identification of 123 volatile compounds that were further processed with chemometric tools. Principal component analysis (PCA) was employed to visualize the clustering of the samples, and a two-way orthogonal partial least squares discriminant analysis (O2PLS-DA) chemometric model was developed and successfully classified the samples to authentic pomegranate juice or adulterated with an explained total variance of 87.4%. The O2PLS-DA prediction model revealed characteristic volatile markers that could be used to detect pomegranate juice fraud.

Adapting to Climate Change with Opuntia

Adapting our food production chain and increasing the flora and fauna's livelihood in climate change-affected areas using Opuntia is not only theoretical but already exists in practice in many places. This cactus grows in unsuitable soil for most species as it is adapted to arid and semi-arid soils and hot weather. In these regions, Opuntia protects from erosion and contributes to soil health. The usage of this plant as fodder is also discussed, with immense potential in substituting a part of livestock's diet and even increasing the quality of the animal's by-products and decreasing water consumption. This would result in a feed that is low-cost and has a lower environmental impact. It is to be noted that Opuntia has a high potential as an invasive species, with caution always being recommended when dealing with this specie. The high content of specific compounds, such as proline, indicaxanthin, and betanin, found in Opuntia ficus-indica, influence the plant's adaptation to unfavourable conditions. This collective evidence depicts Opuntia as a crop that can battle climate change and ensure food security.

Effects of Punica granatum Fruit (a Super Food) Juice on Human Health

Background:

Pomegranate (Punica granatum L.), one of the oldest known edible fruits, is nowadays broadly consumed throughout the world. Its fruits and seed are rich in many bioactive compounds, as polyphenols, and the scientific interest in this plant has been constantly growing in recent years.

Introduction:

Pomegranate fruit and its juice have been shown to have health benefits relating to their antioxidant and anti-inflammatory properties. They are used in alternative medicine as adaptogens and ergogens protecting against many neurological, cardiovascular, gastrointestinal, liver, and skin disorders.

Methods:

Given the amount of evidence, this narrative review does not seek to supply a comprehensive summary of all study findings, but rather focuses on human clinical trials related the last five years. In this regard, we have performed a check in MEDLINE, and clinical trials presented in this time are summarized.

Result:

The use of pomegranate as table fruit or juice, rich source of polyphenols, can so be recommended in human nutrition for its benefic properties. The consumption of pomegranate fruit symbolizes a promising therapeutic approach to avert many chronic syndromes.

Conclusion:

Importantly, the findings call for the need for a larger, rigorously designed human clinical trials to allow continued investigation into the potential specific effects of pomegranate fruit, and to obtain the best dose and duration of supplementation with pomegranate juice.

Authentication of pomegranate juice using multidimensional analysis of its metabolites

With the growing popularity and demand of pomegranate juice, its adulteration has also steadily increased. In this study, to authenticate pure or adulterated juice, the major components of pomegranate juice were compared with those of grape, peach, and apple juices (which are common adulterants in pomegranate juice) using liquid chromatography-electrospray-tandem mass spectrometry, ion chromatography, and inductively coupled plasma spectrometry. The various parameters evaluated were as follows: the ratio of malic acid to citric acid content, presence of tartaric acid, and levels of glucose, fructose, and mannitol, and sucrose. Potassium was the most abundant mineral in pomegranate juice, and the content ratio of other minerals/potassium did not exceed 0.1. The reliability of this method was confirmed in blind tests and monitoring experiments with commercial pomegranate juice. In conclusion, a simple and effective method was developed to detect adulteration in pomegranate juice.

Amino Acid Profiling with Chemometric Analysis as a Feasible Tool for the Discrimination of Marine-Derived Peptide Powders

Marine-derived peptide powders have suffered from adulteration via the substitution of lower-price peptides or the addition of adulterants in the market. This study aims to establish an effective approach for the discrimination and detection of adulterants for four representative categories of marine-derived peptide powders, namely, oyster peptides, sea cucumber peptides, Antarctic krill peptides, and fish skin peptides, based on amino acid profiling alongside chemometric analysis. The principal component analysis and orthogonal partial least squares discriminant analysis results indicate that four categories of marine-derived peptides could be distinctly classified into four clusters and aggregated with the respective raw materials. Taurine, glycine, lysine, and protein contents were the major discriminants. A reliable classification model was constructed and validated by the prediction dataset, mixture sample dataset, and unclassified sample dataset with accuracy values of 100%, 100%, and 100%, respectively.

Effect of By-Products from Selected Fruits and Vegetables on Gluten-Free Dough Rheology and Bread Properties

The aim of the study was to investigate the effect of using various by-products (orange and apple pomace, tomato peel, pepper peel, prickly pear peel, and prickly pear seed peel) on the dough rheology and properties of gluten-free bread. The by-products were incorporated into a gluten-free bread formulation based on corn and chickpea flours (2/1 w/w). Different levels of each by-product (0, 2.5, 5, and 7.5% in the basic replacement) were tested. Wheat bread and gluten-free bread without the addition of by-products were used as controls. The results indicated that the by-products increased the maximum dough height, the total CO2 production, and CO2 retention coefficient compared to unenriched gluten-free dough. The highest K-value consistency coefficient was observed for the dough enriched with the prickly pear peel. The addition of by-products significantly improved (p < 0.0001) the specific volume of gluten-free bread, with values increasing from 1.48 to 2.50 cm3/g. The hierarchical cluster analysis and the constellation plot showed four groups: the wheat bread group, the second group containing the gluten-free control bread, the group with bread enriched by pomace, and the group with bread enriched with peels, exhibit the same effect on gluten-free bread and the peels exhibit the same effect on gluten-free bread.

Rapid Pomegranate Juice Authentication Using a Simple Sample-to-Answer Hybrid Paper/Polymer-Based Lab-on-a-Chip Device

As a super fruit, pomegranate and its juice have attracted increased consumer demands during the past decades. Given the high production cost and market price, adulteration of pomegranate juice is highly likely to occur. To authenticate pomegranate juice and avoid the addition of cheaper fruit juices, such as apple and grape, an analytical method based on loop-mediated isothermal amplification (LAMP) was developed. This LAMP-based authentication method achieved highly sensitive (i.e., 10 pg for pomegranate DNA and 100 pg for grape and apple DNA) and specific detection of pomegranate, apple, and grape DNA present in fresh fruit juice. To further simplify the overall analysis, a hybrid paper/polymer-based lab-on-a-chip (LOC) platform was designed to integrate DNA extraction, LAMP reaction, and LAMP result visualization onto a single device. This LOC device was able to detect 2 μL of fresh pomegranate juice and 5 μL of fresh apple and grape juice. Using a homemade portable heating device, the overall analysis could be completed in ∼1 h in an almost instrument-free setting. The cost for each authentication test is estimated to be ∼4 USD and the reusable homemade portable heating device is ∼15 USD. This LAMP-based simple sample-to-answer hybrid paper/polymer-based LOC device has high potential to be adopted by government laboratories and the food industry to rapidly and routinely authenticate pomegranate juice even in a resource-limited environment.

Determination of Free Tryptophan in Beer Samples by Capillary Isotachophoretic Method

Tryptophan is essential amino acid and precursor for many neurotramsmiters that must be obtained from dietary proteins. However, its free form is easily absorbed and could increase the availability of this amino acid to the brain. Because of free tryptophan interaction with human health simple, eco-friendliness and low-cost method of determination are still needed. In this study, new and simple procedure for free tryptophan determination using capillary isotachophoresis is discussed. The method validation pointed good linearity, satisfactory selectivity, accuracy (recoveries varied from 98.4 to 100.1%), intra- and inter-day precision (coefficent of variation was < 5% for each standard solution and < 6% for real samples) and no matrix effect. The proposed procedure was successfully applied to analyse free tryptophan in beer samples and found contents varied from not detected to 40.74 ± 0.27 mg L−1. The obtained results were compared with chromatographic determination after derivatization with 2-chloro-1,3-dinitro-5-(trifluoromethyl)benzene and pointed better selectivity and accuracy of isotachophoretic procedure with similar precision. Due to the simplicity and flexibility, the proposed procedure is suitable for tryptophan analysis in complex matrices.

Targeted and Untargeted Metabolomics as an Enhanced Tool for the Detection of Pomegranate Juice Adulteration

Pomegranate juice is one of the most popular fruit juices, is well-known as a "superfood", and plays an important role in healthy diets. Due to its constantly growing demand and high value, pomegranate juice is often targeted for adulteration, especially with cheaper substitutes such as apple and red grape juice. In the present study, the potential of applying a metabolomics approach to trace pomegranate juice adulteration was investigated. A novel methodology based on high-resolution mass spectrometric analysis was developed using targeted and untargeted screening strategies to discover potential biomarkers for the reliable detection of pomegranate juice adulteration from apple and red grape juice. Robust classification and prediction models were built with the use of unsupervised and supervised techniques (principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA)), which were able to distinguish pomegranate juice adulteration to a level down to 1%. Characteristic m/z markers were detected, indicating pomegranate juice adulteration, and several marker compounds were identified. The results obtained from this study clearly demonstrate that Mass Spectrometry (MS)-based metabolomics have the potential to be used as a reliable screening tool for the rapid determination of food adulteration.

Quantification of punicalagins in commercial preparations and pomegranate cultivars, by liquid chromatography-mass spectrometry

BACKGROUND

Pomegranate (Punica granatum L.) - a delicious fruit once used in Ayurvedic medicine - is now largely known for the antioxidant properties of its juice, which has also been considered to have health benefits against diseases such as cancer and cardiovascular diseases. These beneficial effects are associated with the fruit's high content of polyphenolic compounds. High demand and lower production levels drive pomegranate prices up, which leads to the possibility of pomegranate products being adulterated, diluted or substituted. To ensure the presence of pomegranate in various preparations labeled as containing pomegranate, a simple method was developed to screen and quantify the specific punicalagins by mass spectrometry.

RESULTS

The present method was used to analyze several pure and mixed beverages from the US market, and also to quantify punicalagins in the juice of 14 pomegranate cultivars. Punicalagins were detected in all cultivars, with higher concentrations in whole fruit juices compared with aril juices. Amongst the 20 commercial beverages, punicalagins were not detected in four preparations.

CONCLUSION

The liquid chromatographic-mass spectrometric method presented herein enables an easy and rapid quantification of the specific punicalagins. The latter was detected in all cultivar samples, thus supporting that punicalagin is a suitable marker of these 14 pomegranate cultivars in commercial juices. Absence of the specific marker in four commercial preparations shows the necessity of having simple and rapid methods to evaluate the presence of pomegranate in preparations. © 2019 Society of Chemical Industry.

Primary Metabolites, Anthocyanins, and Hydrolyzable Tannins in the Pomegranate Fruit

Pomegranate (Punica granatum L.) is an important and interesting fruit tree that is cultivated in many parts of the world. In recent years, along with the increase in its cultivation and consumption there has been a dramatic increase in the scientific interest in its biology, methods of cultivation, adaptation to environmental cues and its health-promoting properties. Quite a large proportion of the various metabolites produced in the pomegranate were determined and their content in the bark, roots, leaves, and fruit was reported. Many reviews on polyphenolic compound content, antioxidant activity and health-promoting compounds were published recently. However, only very few recent reports were dedicated to primary metabolites, despite the fact that much work was done on organic acids, sugars, proteins, lipids, and amino acids of the pomegranate fruit. In this review, a special effort was made to present these recent studies and the review is devoted to primary metabolites. The reported data show high variation in the content of primary metabolites within the pomegranate fruit; therefore the data is presented (whenever possible) according to fruit tissues (peel, arils, and seeds), developmental stages of the fruit, environmental and climatic conditions, and genetic background. Most of the data on pomegranate is based on metabolic content and contains no genetic or molecular analysis except for work done on anthocyanins and hydrolyzable tannins. In those cases, gene assignment and genetic control studies were pointed out in the review. The recent publication of the genome sequences from several pomegranate varieties and transcriptomic data from fruits, flowers, and leaves is expected to facilitate the understanding of genetic control of metabolites in pomegranate.

Quality and Authenticity Control of Fruit Juices-A Review

Food fraud, being the act of intentional adulteration of food for financial advantage, has vexed the consumers and the food industry throughout history. According to the European Committee on the Environment, Public Health and Food Safety, fruit juices are included in the top 10 food products that are most at risk of food fraud. Therefore, reliable, efficient, sensitive and cost-effective analytical methodologies need to be developed continuously to guarantee fruit juice quality and safety. This review covers the latest advances in the past ten years concerning the targeted and non-targeted methodologies that have been developed to assure fruit juice authenticity and to preclude adulteration. Emphasis is placed on the use of hyphenated techniques and on the constantly-growing role of MS-based metabolomics in fruit juice quality control area.

Determination of Free Amino Acids in Three Species of Duckweed (Lemnaceae)

In this study, a fast, simple, precise, and sensitive hydrophilic interaction liquid chromatography (HILIC) method was established for simultaneous determination of free amino acids in three different varieties of duckweed including Spirodela polyrhiza (L.) Schleid., Landoltia punctata (G. Mey.) Les & D. J. Crawford, and Lemna aequinoctialis Welwitsch by ultrahigh performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Method validation was processed in terms of linearity, precision, stability, repeatability, and accuracy as well as limits of detection and quantification. The developed method was applied for quantification of 59 batches of samples. Then chemometric analysis was used to evaluate different duckweeds by principle component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). The results demonstrated that there was no significant difference in FAAs’ profile among three varieties of duckweed.

CE-UV for the characterization of passion fruit juices provenance by amino acids profile with the aid of chemometric tools

A separation method was developed in order to quantify free amino acids in passion fruit juices using CE-UV. A selective derivatization reaction with FMOC followed by MEKC analysis was chosen due to the highly interconnected mobilities of the analytes, enabling the separation of 22 amino acids by lipophilicity differences, as will be further discussed. To achieve such results, the method was optimized concerning BGE composition (concentrations, pH, and addition of organic modifier) and running conditions (temperature and applied voltage). The optimized running conditions were: a BGE composed by 60 mmol/L borate buffer at pH 10.1, 30 mmol/L SDS and 5 % methanol; running for 40 min at 23°C and 25 kV. The method was validated and applied on eight brands plus one fresh natural juice, detecting 12 amino acids. Quantification of six analytes combined with principal component analysis was capable to characterize different types of juices and showed potential to detect adulteration on industrial juices. Glutamic acid was found to be the most concentrated amino acid in all juices, exceeding 1 g/L in all samples and was also crucial for the correct classification of a natural juice, which presented a concentration of 22 g/L.

Derivatization in Capillary Electrophoresis

Capillary electrophoresis is a well-established separation technique in analytical research laboratories worldwide. Its interesting advantages make CE an efficient and potent alternative to other chromatographic techniques. However, it is also recognized that its main drawback is the relatively poor sensitivity when using optical detection. One way to overcome this limitation is to perform a derivatization reaction which is intended to provide the analyte more suitable analytical characteristics enabling a high sensitive detection. Based on the analytical step where the CE derivatization takes place, it can be classified as precapillary (before separation), in-capillary (during separation), or postcapillary (after separation). This chapter describes the application of four different derivatization protocols (in-capillary and precapillary modes) to carry out the achiral and chiral analysis of different compounds in food and biological samples with three different detection modes (UV, LIF, and MS).

Improving the sensitivity in chiral capillary electrophoresis

CE is known for being one of the most powerful analytical techniques when performing enantioseparations due to its numerous advantages such as excellent separation efficiency and extremely low solvents and reagents consumption, all of them derived from the capillary small dimensions. Moreover, it is worth highlighting that unlike in chromatographic techniques, in CE the chiral selector is generally within the separation medium instead of being attached to the separation column which makes the method optimization a more versatile task. Despite its numerous advantages, when using UV-Vis detection, CE lacks of sensitivity detection due to its short optical path length derived from the narrow separation capillary. This issue can be overcome by means of different approaches, either by sample treatment procedures or by in-capillary preconcentration techniques or even by employing detection systems more sensitive than UV-Vis, such as LIF or MS. The present review assembles the latest contributions regarding improvements of sensitivity in chiral CE published from June 2013 until May 2015, which follows the works included in a previous review reported by Sánchez-Hernández et al. [Electrophoresis 2014, 35, 12-27].

Efficacy and safety of pomegranate medicinal products for cancer

Preclinical in vitro and in vivo studies demonstrate potent effects of pomegranate preparations in cancer cell lines and animal models with chemically induced cancers. We have carried out one systematic review of the effectiveness of pomegranate products in the treatment of cancer and another on their safety. The PubMed search provided 162 references for pomegranate and cancer and 122 references for pomegranate and safety/toxicity. We identified 4 clinical studies investigating 3 pomegranate products, of which one was inappropriate because of the low polyphenol content. The evidence of clinical effectiveness was poor because the quality of the studies was poor. Although there is no concern over safety with the doses used in the clinical studies, pomegranate preparations may be harmful by inducing synthetic drug metabolism through activation of liver enzymes. We have analysed various pomegranate products for their content of anthocyanins, punicalagin, and ellagic acid in order to compare them with the benchmark doses from published data. If the amount of coactive constituents is not declared, patients risk not benefiting from the putative pomegranate effects. Moreover, pomegranate end products are affected by many determinants. Their declaration should be incorporated into the regulatory guidance and controlled before pomegranate products enter the market.

Enhancement of native fluorescence intensity of berberine by (2-hydroxypropyl)-β-cyclodextrin in capillary electrophoresis coupled by laser-induced fluorescence detection: application to quality control of medicinal plants

A sensitive method for the determination of berberine, a plant alkaloid, was developed by capillary electrophoresis coupled with laser induced fluorescence detection. With the addition of (2-hydroxypropyl)-β-cyclodextrin (2-HP-β-CD) to the separation electrolyte, the low fluorescence signal intensity of berberine in aqueous medium was enhanced considerably by 162 fold. The optimal background electrolyte was selected as 20mM acetic acid, 35mM 2-HP-β-CD, and 20% methanol at pH 5. The limit of detection of the method for berberine was 15.7ng/mL. The intra and interday repeatabilities of corrected peak areas as RDSs were 1.83% and 3.75%, respectively. The developed method was successfully applied for the determination of berberine contents in Chinese medicinal plants and herbal supplemental tablets.