Floral classification of honey using liquid chromatography-diode array detection-tandem mass spectrometry and chemometric analysis

Phenolic profiles of Australian monofloral Eucalyptus, Corymbia, Macadamia and Lophostemon honeys via HPLC-DAD analysis

Australian honey samples from four botanical genera (Lophostemon, Eucalyptus, Macadamia and Corymbia) were investigated for their phenolic content. An improved phenolic extraction and high-performance liquid chromatography-diode array detection (HPLC-DAD) analysis method allowed for the rapid and reliable identification of phenolic compounds. A concentrated liquid-liquid extraction method with an acidified aqueous solution and acetonitrile was optimised to isolate phenolic compounds from the honey matrix. The concentrated extraction method improved sensitivity and permitted the identification of phenolics present at low concentrations (LOD: 0.012-0.25 mg/kg and LOQ: 0.040-2.99 mg/kg). The optimised HPLC-DAD chromatographic conditions gave stable retention times, improved peak separation and allowed for the inexpensive detection of each of the 109 phenolic compounds at their maximum absorbance wavelength. Out of the 109 phenolic compounds included in this study, 49 were identified in the Australian honeys tested. Furthermore, 25 of the 49 compounds were determined to be markers specific to honey floral origin.

Mass Spectrometry Characterization of Honeydew Honey: A Critical Review

Honeydew honey is produced by bees (Apis mellifera) foraging and collecting secretions produced by certain types of aphids on various parts of plants. In addition to exhibiting organoleptic characteristics that distinguish them from nectar honey, these honeys are known for their functional properties, such as strong antioxidant and anti-inflammatory activities. Despite their importance, they remain poorly characterized in comparison with flower honeys, as most studies on this subject are not only carried out on too few samples but also still focused on traditional chemical-physical parameters, such as specific rotation, major sugars, or melissopalynological information. Since mass spectrometry has consistently been a primary tool for the characterization and authentication of honeys, this review will focus on the application of these methods to the characterization of the minor fraction of honeydew honey. More specifically, this review will attempt to highlight what progress has been made so far in identifying markers of the authenticity of the botanical and/or geographical origin of honeydew honeys by mass spectrometry-based approaches. Furthermore, strategies devoted to the determination of contaminants and toxins in honeydew honeys will be addressed. Such analyses represent a valuable tool for establishing the level of food safety associated with these products. A critical analysis of the presented studies will identify their limitations and critical issues, thereby describing the current state of research on the topic.

Exploring the Formation of Chemical Markers in Chaste Honey by Comparative Metabolomics: From Nectar to Mature Honey

Identification of chemical markers is important to ensure the authenticity of monofloral honey; however, the formation of chemical markers in honey has received little attention. Herein, using comparative metabolomics, we first identified chemical markers in chaste honey and then explored their formation and accumulation from nectar to mature honey. We identified agnuside and p-hydroxybenzoic acid glucosides as chemical markers for chaste honey. Besides, we developed an UHPLC-MS/MS method for quantifying these markers and found that their levels varied significantly across sample sources. We compared the presence of these compounds in chaste nectar and mature honey. The outcomes underscore that these characteristic compounds are not simply delivered from nectar to mature honey, and activities of honeybees (collecting and processing) play a pivotal role in their formation and accumulation. These observations shed light on how mature honey can form its unique qualities with a rich assortment of natural bioactive compounds, potentially supporting health benefits.

Determination of adulteration, geographical origins, and species of food by mass spectrometry

Food adulteration, mislabeling, and fraud, are rising global issues. Therefore, a number of precise and reliable analytical instruments and approaches have been proposed to ensure the authenticity and accurate labeling of food and food products by confirming that the constituents of foodstuffs are of the kind and quality claimed by the seller and manufacturer. Traditional techniques (e.g., genomics-based methods) are still in use; however, emerging approaches like mass spectrometry (MS)-based technologies are being actively developed to supplement or supersede current methods for authentication of a variety of food commodities and products. This review provides a critical assessment of recent advances in food authentication, including MS-based metabolomics, proteomics and other approaches.

Honeybees' foraging choices for nectar and pollen revealed by DNA metabarcoding

Honeybees are the most widespread managed pollinators of our food crops, and a crucial part of their well-being is a suitable diet. Yet, we do not know how they choose flowers to collect nectar or pollen from. Here we studied forty-three honeybee colonies in six apiaries over a summer, identifying the floral origins of honey and hive-stored pollen samples by DNA-metabarcoding. We recorded the available flowering plants and analyzed the specialized metabolites in honey. Overall, we find that honeybees use mostly the same plants for both nectar and pollen, yet per colony less than half of the plant genera are used for both nectar and pollen at a time. Across samples, on average fewer plant genera were used for pollen, but the composition was more variable among samples, suggesting higher selectivity for pollen sources. Of the available flowering plants, honeybees used only a fraction for either nectar or pollen foraging. The time of summer guided the plant choices the most, and the location impacted both the plants selected and the specialized metabolite composition in honey. Thus, honeybees are selective for both nectar and pollen, implicating a need of a wide variety of floral resources to choose an optimal diet from.

Headspace with Gas Chromatography-Mass Spectrometry for the Use of Volatile Organic Compound Profile in Botanical Origin Authentication of Honey

The botanical origin of honey determines its composition and hence properties and product quality. As a highly valued food product worldwide, assurance of the authenticity of honey is required to prevent potential fraud. In this work, the characterisation of Spanish honeys from 11 different botanical origins was carried out by headspace gas chromatography coupled with mass spectrometry (HS-GC-MS). A total of 27 volatile compounds were monitored, including aldehydes, alcohols, ketones, carboxylic acids, esters and monoterpenes. Samples were grouped into five categories of botanical origins: rosemary, orange blossom, albaida, thousand flower and "others" (the remaining origins studied, due to the limitation of samples available). Method validation was performed based on linearity and limits of detection and quantification, allowing the quantification of 21 compounds in the different honeys studied. Furthermore, an orthogonal partial least squares-discriminant analysis (OPLS-DA) chemometric model allowed the classification of honey into the five established categories, achieving a 100% and 91.67% classification and validation success rate, respectively. The application of the proposed methodology was tested by analysing 16 honey samples of unknown floral origin, classifying 4 as orange blossom, 4 as thousand flower and 8 as belonging to other botanical origins.

Evaluation of the Antioxidant Activities and Phenolic Profile of Shennongjia Apis cerana Honey through a Comparison with Apis mellifera Honey in China

This study evaluates the phenolic profile as well as the antioxidant properties of Shennongjia Apis cerana honey through a comparison with Apis mellifera honey in China. The total phenolic content (TPC) ranges from 263 ± 2 to 681 ± 36 mg gallic acid/kg. The total flavonoids content (TFC) ranges from 35.9 ± 0.4 to 102.2 ± 0.8 mg epicatechin/kg. The correlations between TPC or TFC and the antioxidant results (FRAP, DPPH, and ABTS) were found to be statistically significant (p < 0.01). Furthermore, the phenolic compounds are quantified and qualified by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS), and a total of 83 phenolic compounds were tentatively identified in this study. A metabolomics analysis based on the 83 polyphenols was carried out and subjected to principal component analysis and orthogonal partial least squares-discriminant analysis. The results showed that it was possible to distinguish Apis cerana honey from Apis mellifera honey based on the phenolic profile.

The Bioactive Value of Tamarix gallica Honey from Different Geographical Origins

This study was conducted to assess the bioactive value of Tamarix gallica honey samples collected from three countries. In total, 150 Tamarix gallica honey samples from Saudi Arabia (50), Libya (50), and Egypt (50) were collected and compared, based on the results of the melissopalynological analysis, their physicochemical attributes, antioxidant and antimicrobial activities, and biochemical properties, together with their total phenolic and total flavonoid contents. Depending on the geographical origin, we observed different levels of growth suppression for six resistant bacterial strains. The pathogenic microorganisms tested in this study were Staphylococcus aureus, Streptococcus mutans, Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris, and Pseudomonas aeruginosa. There was a strong correlation between the polyphenol and flavonoid contents, as well as significant (p < 0.05) radical scavenging activities. The melissopalynological analysis and physicochemical properties complied with the recommendation of the Gulf and Egyptian Technical Regulations on honey, as well as the Codex Alimentarius of the World Health Organization and the European Union Normative related to honey quality. It was concluded that Tamarix gallica honey from the three countries has the capacity to suppress pathogenic bacterial growth and has significant radical scavenging activities. Moreover, these findings suggest that Tamarix gallica honey may be considered as an interesting source of antimicrobial compounds and antioxidants for therapeutical and nutraceutical industries or for food manufacturers.

A non-targeted metabolomic strategy for characterization of the botanical origin of honey samples using headspace gas chromatography-ion mobility spectrometry

In this work, characterization of the botanical origin of honey was carried out using headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS). The proposed methodology was applied for the analysis of 89 samples from ten different botanical origins. A total of 15 volatile compounds could be identified, namely, 3-methyl-1-butanol, heptanal, valeraldehyde, octanal, trans-2-hexenal, nonanal, hexanal, benzaldehyde, 2-heptanone, 2-butanone, 2-hexanone, 6-methyl-5-hepten-2-one, 2-pentanone, ethyl acetate and linalool. The analytical method was characterized in terms of limits of detection and quantification, and precision, in order to quantify the identified compounds. Compounds were quantified using the sum of the protonated monomer and proton-bound dimer and logarithmic regression (R² > 0.98), although the establishment of a concentration threshold that would allow creation of classification rules was not possible since there was variability within the group. Consequently, the establishment of chemometric models was necessary. A non-targeted strategy using 275 features is proposed. Orthogonal partial least squares-discriminant analysis (OPLS-DA) allowed the differentiation of five botanical origins: thousand flowers, rosemary, albaida, orange blossom, and "others" (rest of the investigated botanical origins, since a limited number of samples was available). A success validation rate of 100% allowed the classification of 14 honeys with unknown botanical origin.

Characterization, Classification and Authentication of Spanish Blossom and Honeydew Honeys by Non-Targeted HPLC-UV and Off-Line SPE HPLC-UV Polyphenolic Fingerprinting Strategies

Honey is a highly consumed natural product produced by bees which is susceptible to fraudulent practices, some of them regarding its botanical origin. Two HPLC-UV non-targeted fingerprinting approaches were evaluated in this work to address honey characterization, classification, and authentication based on honey botanical variety. The first method used no sample treatment and a universal reversed-phase chromatographic separation. On the contrary, the second method was based on an off-line SPE preconcentration method, optimized for the isolation and extraction of polyphenolic compounds, and a reversed-phase chromatographic separation optimized for polyphenols as well. For the off-line SPE method, the use of HLB (3 mL, 60 mg) cartridges, and 6 mL of methanol as eluent, allowed to achieve acceptable recoveries for the selected polyphenols. The obtained HPLC-UV fingerprints were subjected to an exploratory principal component analysis (PCA) and a classificatory partial least squares-discriminant analysis (PLS-DA) to evaluate their viability as sample chemical descriptors for authentication purposes. Both HPLC-UV fingerprints resulted to be appropriate to discriminate between blossom honeys and honeydew honeys. However, a superior performance was accomplished with off-line SPE HPLC-UV polyphenolic fingerprints, being able to differentiate among the different blossom honey samples under the study (orange/lemon blossom, rosemary, thyme, eucalyptus, and heather). In general, this work demonstrated the feasibility of HPLC-UV fingerprints, especially those obtained after off-line SPE polyphenolic isolation and extraction, to be employed as honey chemical descriptors to address the characterization and classification of honey samples according to their botanical origin.

Study on stable carbon isotope fractionation of rape honey from rape flowers (Brassica napus L.) to its unifloral ripe honey

A new idea and strategy for honey traceability and identification was provided by studying the carbon isotope fractionation of rape honey and its components in the different ripening process, as well as the fractionation from rape flowers, stamens, nectar to rape honey. The results showed the moisture content of rape honey continued to decrease, and the glucose and fructose content continued to increase during the ripening process. The δ¹³C of rape honey and its protein were less affected by honey ripeness, while the δ¹³C of sugars in rape honey were greatly affected by this. At the same time, the fractionation of carbon isotope from rape flowers to honey was significant. The δ¹³C of rape honey and its protein, disaccharide, fructose, and glucose had a strong correlation, and the δ¹³C of rape honey and its components were mainly related to rape flowers and its stamens.

AUTENTIKASI CEPAT MADU HUTAN KALIMATAN TIMUR DENGAN ATR-FTIR SPEKTROSKOPI KOMBINASI ANALISIS KEMOMETRIKA

Honey adulteration is mostly conducted by the addition of sucrose. In this study, the authentication of honey was conducted using ATR-FTIR and chemometrics. Pure honey samples (MA) were collected from nine regions in East Kalimantan. The ATR-FTIR spectra of these samples were then compared to sucrose-adulterated honey (MS), which were prepared in the sucrose concentration from 2.5 to 50% (v / v).The data analysis was performed using chemometrics techniques: 1) Principle Component Analysis (PCA) method, 2) classification with Discriminant Analysis (DA), and 3) regression with (PCR) and (PLS). As a result, PCA was able to visualize the differences between MS and MA. DA analysis was able to distinguish MS and MA at wave numbers from 1200 to 800 cm-1 with 92.5% performance index. Quantitative calibration models of the sucrose-adulterated honey could be obtained from PLS and PCR, while the best calibration model was obtained with the PLS method from the 2nd derivative spectra. In summary, sucrose-adulterated honey from East Kalimantan can be authenticated using ATR-FTIR method in combination with chemometric analysis.

Non-Targeted Screening Approaches for Profiling of Volatile Organic Compounds Based on Gas Chromatography-Ion Mobility Spectroscopy (GC-IMS) and Machine Learning

Due to its high sensitivity and resolving power, gas chromatography-ion mobility spectrometry (GC-IMS) is a powerful technique for the separation and sensitive detection of volatile organic compounds. It is a robust and easy-to-handle technique, which has recently gained attention for non-targeted screening (NTS) approaches. In this article, the general working principles of GC-IMS are presented. Next, the workflow for NTS using GC-IMS is described, including data acquisition, data processing and model building, model interpretation and complementary data analysis. A detailed overview of recent studies for NTS using GC-IMS is included, including several examples which have demonstrated GC-IMS to be an effective technique for various classification and quantification tasks. Lastly, a comparison of targeted and non-targeted strategies using GC-IMS are provided, highlighting the potential of GC-IMS in combination with NTS.

Chemical Analyses and Antimicrobial Activity of Nine Kinds of Unifloral Chinese Honeys Compared to Manuka Honey (12+ and 20+)

Honey has good antimicrobial properties and can be used for medical treatment. The antimicrobial properties of unifloral honey varieties are different. In this study, we evaluated the antimicrobial and antioxidant activities of nine kinds of Chinese monofloral honeys. In addition, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology was used to detect their volatile components. The relevant results are as follows: 1. The agar diffusion test showed that the diameter of inhibition zone against Staphylococcus aureus of Fennel honey (21.50 ± 0.41 mm), Agastache honey (20.74 ± 0.37 mm), and Pomegranate honey (18.16 ± 0.11 mm) was larger than that of Manuka 12+ honey (14.27 ± 0.10 mm) and Manuka 20+ honey (16.52 ± 0.12 mm). The antimicrobial activity of Chinese honey depends on hydrogen peroxide. 2. The total antioxidant capacity of Fennel honey, Agastache honey, and Pomegranate honey was higher than that of other Chinese honeys. There was a significant positive correlation between the total antioxidant capacity and the total phenol content of Chinese honey (r = 0.958). The correlation coefficient between the chroma value of Chinese honey and the total antioxidant and the diameter of inhibition zone was 0.940 and 0.746, respectively. The analyzed dark honeys had better antimicrobial and antioxidant activities. 3. There were significant differences in volatile components among Fennel honey, Agastache honey, Pomegranate honey, and Manuka honey. Hexanal-D and Heptanol were the characteristic components of Fennel honey and Pomegranate honey, respectively. Ethyl 2-methylbutyrate and 3-methylpentanoic acids were the unique compounds of Agastache honey. The flavor fingerprints of the honey samples from different plants can be successfully built using HS-GC-IMS and principal component analysis (PCA) based on their volatile compounds. Fennel honey, Agastache honey, and Pomegranate honey are Chinese honey varieties with excellent antimicrobial properties, and have the potential to be developed into medical grade honey.

Honey authenticity: analytical techniques, state of the art and challenges

Honey is a high-value, globally consumed, food product featuring a high market price strictly related to its origin. Moreover, honey origin has to be clearly stated on the label, and quality schemes are prescribed based on its geographical and botanical origin. Therefore, to enhance food quality, it is of utmost importance to develop analytical methods able to accurately and precisely discriminate honey origin. In this study, an all-time scientometric evaluation of the field is provided for the first time using a structured keyword on the Scopus database. The bibliometric analysis pinpoints that the botanical origin discrimination was the most studied authenticity issue, and chromatographic methods were the most frequently used for its assessment. Based on these results, we comprehensively reviewed analytical techniques that have been used in honey authenticity studies. Analytical breakthroughs and bottlenecks on methodologies to assess honey quality parameters using separation, bioanalytical, spectroscopic, elemental and isotopic techniques are presented. Emphasis is given to authenticity markers, and the necessity to apply chemometric tools to reveal them. Altogether, honey authenticity is an ever-growing field, and more advances are expected that will further secure honey quality.

Floral tea polyphenols can improve honey bee memory retention and olfactory sensitivity

Animal-pollinated plants face a common problem, how their defensive anti-herbivore compounds may impair or alter pollinator behavior. Evolution has tailored multiple solutions, which largely involve pollinator tolerance or manipulation, to the benefit of the plant, not the removal of these compounds from pollen or nectar. The tea plant, Camilla sinensis, is famous for the caffeine and tea polyphenols (TP) that it produces in its leaves. However, these compounds are also found in its nectar, which honey bees readily collect. We examined the effects of these compounds on bee foraging choices, learning, memory, and olfactory sensitivity. Foragers preferred a sucrose feeder with 100 µg or 10 µg TP/ml over a control feeder. Caffeine, but not TP, weakly increased honey bee learning. Both caffeine and TP significantly increased memory retention, even when tested 7 d after the last learning trial. In addition, TP generally elevated EAG responsiveness to alarm pheromone odors. These results demonstrate that other secondary plant compounds, not only caffeine, can attract pollinators and influence their learning and memory.

Melissopalynology and antioxidant properties used to differentiate Schefflera abyssinica and polyfloral honey

Honey can be categorized as monofloral and polyfloral honey. There is a strong interest in science and commerce, to further differentiate honey. In the present study, Schefflera abyssinica and polyfloral honey from Sheka Forest, Ethiopia was investigated. Botanical origin was determined based on Melissopalynology. Refractive index, moisture, sugars, ash, pH, free acidity, hydroxymethylfurfural, optical density, diastase activity, protein, and color were determined based on the standard method of the international honey commission (IHC) and AOAC. Antioxidant activity and Antioxidant content were determined using UV- visible spectroscopy. The level of pollen dominancy for monofloral honey (Schefflera abyssinica) ranged from 76.2 to 85.8%. The polyfloral honey stuffed with a variety of pollen grain ranged from 2.2% (Coffea arabica) to 23.2% (Schefflera abyssinica). Schefflera abyssinica honey contained more total phenolic compounds (75.08 ± 2.40 mg GAE/100g), and total flavonoids (42.03 ± 1.49 mg QE/100 g), as well as had stronger DPPH (44.43 ± 0.97%) and hydrogen peroxide (78.00 ± 4.82%) scavenging activity. The principal component analysis revealed that Schefflera abyssinica honey associated with the antioxidant properties of total phenolic, total flavonoids, DPPH, and H2O2., which revealed that floral honey sources can essentially differentiated by antioxidant patterns. The higher electrical conductivity (0.42 ± 0.02 mS/cm), ash (0.41 ± 0.05 g/100g), pH (4.01 ± 0.08), optical density (0.26 ± 0.03) and diastase activity (5.21 ± 0.17 Schade units) were recorded in polyfloral honey. Schefflera abyssinica and polyfloral honey satisfy the requirement of national and international standards. The pollen analysis in combination with antioxidant properties distinguishes Schefflera abyssinica from polyfloral honeys.

Geographical origin and botanical type honey authentication through elemental metabolomics via chemometrics

The trace and rare earth elements content of 93 honeys of different botanical type and origin have been studied through ICP-MS. Discriminant Analysis (DA) was successful for botanical type and geographical origin classification while Cluster Analysis (CA) was successful only for botanical type. Through Probabilistic Neural Network (PNN) analysis, 85.3% were correctly classified by the network according to their geographical origin and 73.3% according to their organic characterization. A Partial Least Squares (PLS) model was constructed, giving a prediction accuracy of more than 95%. Information obtained using Rare Earths (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and trace elements (Li, Mg, Mn, Ni, Co, Cu, Sr, Ba, Pb) via chemometric evaluation facilitated classification of honey samples.

Modern Methods for Assessing the Quality of Bee Honey and Botanical Origin Identification

This paper is a summary of the latest literature on methods for assessing quality of natural bee honey. The publication briefly characterizes methods recommended by the International Honey Commission, published in 2009, as well as newer methods published in the last 10 years. Modern methods of assessing honey quality focus mainly on analyzing markers of individual varieties and classifying them into varieties, using, among others, near infrared spectroscopy techniques (NIR), potentiometric tongue, electronic nose, nuclear magnetic resonance (NMR), zymography, polymerase chain reaction (PCR), DNA metabarcoding, and chemometric techniques including partial least squares (PLS), principal component analysis (PCA) and artificial neural networks (ANN). At the same time, effective techniques for analyzing adulteration, sugar, and water content, hydroxymethylfurfural (HMF), polyphenol content, and diastase activity are being sought. Modern techniques enable the results of honey quality testing to be obtained in a shorter time, using the principles of green chemistry, allowing, at the same time, for high precision and accuracy of determinations. These methods are constantly modified, so that the honey that is on sale is a product of high quality. Prospects for devising methods of honey quality assessment include the development of a fast and accurate alternative to the melissopalynological method as well as quick tests to detect adulteration.

Indonesian wild honey authenticity analysis using attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy combined with multivariate statistical techniques

Wild honeys in Indonesia are still widely believed to be good for health with high economic value. This honey is naturally produced by Apisdorsata bee. In this study, authentication analysis by classification and discrimination of attenuated total reflectance-fourier infrared spectroscopy (ATR-FTIR) spectra was conducted on several wild honeys from various places in Indonesia (n = 186) which then compared to adulterated honey contained commercial sugars of aren (Arenga pinnata), coconut, and cane sugar at 10-50% concentration (n = 57). Combination of spectra measurement at 4,000-650 cm-1 with Chemometric technique by several multivariate analyses resulted in visualization of honey grouping, classification, and regression model that differentiate these honeys, both partial and overall. Principle component analysis multivariate analysis was able to visualize the differentiation of adulterated honey from the authentic ones. Discriminant analysis, a supervised classification technique, was used to differentiate the fake from the authentic honey among those from various origins at wave number range of 4000-800 cm-1 with performance index of 91,8, 90.32-100% sensitivity, and 95. 70-100% specificity. Partial least-squares analysis was used to build a model provided quantitative results of commercial sugars content in honey allegedly added during adulteration. Authentic honeys had commercial sugars content less than 10% with R2 of aren, coconut, and cane sugar of 0.9995, 0.9980 and 0.9998, respectively, with their predictive R2 values of 0.9977, 0.9983 and 0.9946, respectively.

Untargeted and Targeted Discrimination of Honey Collected by Apis cerana and Apis mellifera Based on Volatiles Using HS-GC-IMS and HS-SPME-GC-MS

Fraudulent acts regarding honey authenticity that use Apis mellifera honey as a substitute for Apis cerana honey have garnered considerable concern in China and triggered a trust crisis from consumers. In this study, untargeted metabolomics analysis was carried out based on volatile fractions in honey from A. cerana and A. mellifera using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Honey from A. cerana and A. mellifera was discriminated by HS-GC-IMS profiling, principal component analysis, and orthogonal partial least-squares discrimination analysis. Tentative markers were identified from p-values and the variable importance in projection analysis and confirmed using the retention index, mass fragments, and reference standards by gas chromatography-mass spectrometry (GC-MS). A targeted method was established using the headspace solid phase coupled with microextraction GC-MS (HS-SPME-GC-MS) to quantitate the markers. The results demonstrated that the developed untargeted and targeted metabolomics approach performed well when discriminating honey from A. cerana and A. mellifera.

Establishing authenticity of honey via comprehensive Romanian honey analysis

Assessing the authenticity of honey is a serious problem that has gained much interest internationally because honey has frequently been subject to various fraudulent practices, including mislabelling of botanical and geographical origin and mixing with sugar syrups or honey of lower quality. To protect the health of consumers and avoid competition, which could create an unstable market, consumers, beekeepers and regulatory bodies are interested in having reliable analytical methodologies to detect non-compliant honey. This paper gives an overview of the different approaches used to assess the authenticity of honey, specifically by the application of advanced instrumental techniques, including spectrometric, spectroscopic and chromatographic methods coupled with chemometric interpretation of the data. Recent development in honey analysis and application of the honey authentication process in the Romanian context are highlighted, and future trends in the process of detecting and eliminating fraudulent practices in honey production are discussed.

Vitellaria paradoxa nutshells from seven sub-Saharan countries as potential herbal medicines for treating diabetes based on chemical compositions, HPLC fingerprints and bioactivity evaluation

The aim of the study was to determine the feasibility of the Vitellaria paradoxa nutshell as a new medicinal resource for treating diabetes. A total of forty-one compounds were identified by HPLC-DAD-Q-TOF-MS and phytochemical methods in V. paradoxa nutshell methanol extract. Based on HPLC fingerprints, four characteristic constituents were quantified and the origin of twenty-eight V. paradoxa nutshells from seven sub-Saharan countries was compared, which were classified into three groups with chemometric method. Twenty-eight samples contained high total phenolic content, and exhibited moderate-higher antioxidant activity and strong α-glucosidase inhibitory activity. Furthermore, all fractions and isolated compounds were evaluated for their antioxidant and α-glucosidase inhibitory activities, and α-glucosidase inhibitory action mechanism of four characteristic constituents including protocatechuic acid, 3, 5, 7-trihydroxycoumarin, (2R, 3R)-(+)-taxifolin and quercetin was investigated via molecular docking method, which were all stabilized by hydrogen bonds with α-glucosidase. The study provided an effective approach to waste utilization of V. paradoxa nutshell, which would help to resolve waste environmental pollution and provide a basis for developing potential herbal resource for treating diabetes.

Phenolic compounds profile and biochemical properties of honeys in relationship to the honey floral sources

INTRODUCTION

Honey has been considered to have therapeutic properties since ancient times and among the factors responsible for such activity are phenolic compounds including phenolic acids and flavonoids from different natural sources.

OBJECTIVE

This study investigated the phenolic compounds profile and bioactive properties of different honey types from Romanian flora in order to develop reliable tools for honey floral origin, thus contributing to the honey traceability in the European Union context.

MATERIAL AND METHODS

Thirty-three honey samples were examined, including unifloral (acacia and rape), polyfloral, honeydew honeys and mixture honeys. Phenolic acids and flavonoids were isolated from the water soluble honey matrix using a solid-phase extraction (SPE) method and analysed by ultra-high-performance liquid chromatography diode array detector electrospray ionisation mass spectrometry (UHPLC-DAD-ESI/MS). Honey bioactive properties were measured in honey dissolved in 80% ethanol using UV-visible spectrophotometric methods. Multivariate statistical tools (principal component analysis and hierarchical clustering analysis) were used for honey classification.

RESULTS

The results of this study confirm that honey samples had similar, but quantitatively different, phenolic acids and flavonoids profiles and bioactive properties, related with honey floral source. Coloured honeys, such as honeydew honey, show high phenolic composition and bioactive properties and implicitly a high therapeutic potential compared with the other floral honeys.

CONCLUSION

Distinctive clusters obtained by principal component analysis enabled us to consider that honeydew and polyfloral honeys could be distinguished from acacia and rape honey with the analytical methods developed. Based on this study, the methods might be promising tools for honey traceability, which needs to be explored on a larger set of samples with different regional floral origins in future studies.

Classification of Raw Stingless Bee Honeys by Bee Species Origins Using the NMR- and LC-MS-Based Metabolomics Approach

The official standard for quality control of honey is currently based on physicochemical properties. However, this method is time-consuming, cost intensive, and does not lead to information on the originality of honey. This study aims to classify raw stingless bee honeys by bee species origins as a potential classifier using the NMR-LCMS-based metabolomics approach. Raw stingless bee honeys were analysed and classified by bee species origins using proton nuclear magnetic resonance (¹H-NMR) spectroscopy and an ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF MS) in combination with chemometrics tools. The honey samples were able to be classified into three different groups based on the bee species origins of Heterotrigona itama, Geniotrigona thoracica, and Tetrigona apicalis. d-Fructofuranose (H. itama honey), β-d-Glucose, d-Xylose, α-d-Glucose (G. thoracica honey), and l-Lactic acid, Acetic acid, l-Alanine (T. apicalis honey) ident d-Fructofuranose identified via ¹H-NMR data and the diagnostic ions of UHPLC-QTOF MS were characterized as the discriminant metabolites or putative chemical markers. It could be suggested that the quality of honey in terms of originality and purity can be rapidly determined using the classification technique by bee species origins via the ¹H-NMR- and UHPLC-QTOF MS-based metabolomics approach.

Quantitative and Discriminative Evaluation of Contents of Phenolic and Flavonoid and Antioxidant Competence for Chinese Honeys from Different Botanical Origins

Phenolics and flavonoids in honey are considered as the main phytonutrients which not only act as natural antioxidants, but can also be used as floral markers for honey identification. In this study, the chemical profiles of phenolics and flavonoids, antioxidant competences including total phenolic content, DPPH and ABTS assays and discrimination using chemometric analysis of various Chinese monofloral honeys from six botanical origins (acacia, Vitex, linden, rapeseed, Astragalus and Codonopsis) were examined. A reproducible and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was optimized and validated for the simultaneous determination of 38 phenolics, flavonoids and abscisic acid in honey. Formononetin, ononin, calycosin and calycosin-7-O-β-d-glucoside were identified and quantified in honeys for the first time. Principal component analysis (PCA) showed obvious differences among the honey samples in three-dimensional space accounting for 72.63% of the total variance. Hierarchical cluster analysis (HCA) also revealed that the botanical origins of honey samples correlated with their phenolic and flavonoid contents. Partial least squares-discriminant analysis (PLS-DA) classification was performed to derive a model with high prediction ability. Orthogonal partial least squares-discriminant analysis (OPLS-DA) model was employed to identify markers specific to a particular honey type. The results indicated that Chinese honeys contained various and discriminative phenolics and flavonoids, as well as antioxidant competence from different botanical origins, which was an alternative approach to honey identification and nutritional evaluation.

Development and validation of modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite in various types of honey and royal jelly

Over the past few decades, honey products have been polluted by different contaminants, such as pesticides, which are widely applied in agriculture. In this work, a modified EN - quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method was developed for the simultaneous quantification of pesticide residues, including cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite 2,4-dimethylaniline (2,4-DMA), in four types of honey (acacia, wild, chestnut, and manuka) and royal jelly. Samples were buffered with 0.2M dibasic sodium phosphate (pH 9), and subsequently, acetonitrile was employed as the extraction solvent. A combination of primary secondary amine (PSA) and C18 sorbents was used for purification prior to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI⁺/MS-MS) analysis. The estimated linearity measured at six concentration levels presented good correlation coefficients (R²)≥0.99. The recovery, calculated from three different spiking levels, was 62.06-108.79% in honey and 67.58-106.34% in royal jelly, with an RSD<12% for all the tested compounds. The matrix effect was also evaluated, and most of the analytes presented signal enhancement. The limits of quantification (LOQ) ranged between 0.001 and 0.005mg/kg in various samples. These are considerably lower than the maximum residue limits (MRL) set by various regulatory authorities. A total of 43 market (domestic and imported) samples were assayed for method application. Among the tested samples, three samples were tested positive (i.e. detected and quantified) only for cymiazole residues. The residues in the rest of the samples were detected but not quantified. We concluded that the protocol developed in this work is simple and versatile for the routine quantification of cymiazole, 2,4-DMA, fipronil, coumaphos, amitraz, and fluvalinate in various types of honey and royal jelly.

The Microbial Community Dynamics during the Vitex Honey Ripening Process in the Honeycomb

The bacterial and fungal communities of vitex honey were surveyed by sequencing the 16S rRNA gene and the internal transcribed spacer region of ribosomal DNA. Vitex honey samples were analyzed at different stage of ripening; the vitex flower was also analyzed, and the effect of the chemical composition in the experimental setup was assessed. The results confirmed the presence of dominant Bacillus spp. as the dominant bacterial in honey, and yeast related genera was the main fungal in the honey, respectively. Lactococcus and Enterococcus were detected for the first time in honey. The proportion of most of the fungal community decreased during the honey ripening process. Multivariate analyses also showed that the fungal community of 5, 10, and 15 days honey samples tended to cluster together and were completely separated from the 1 day honey sample. The change in the fungal community showed a correlation with the variation in the chemical components, such as moisture and phenolic compounds. Together, these results suggest that ripening of honey could change its microbial composition, and decrease the potential risk of microbiology.

Implementation of chemometrics in quality evaluation of food and beverages

Conventional methods for food quality evaluation based on chemical or microbiological analysis followed by traditional univariate statistics such as ANOVA are considered insufficient for some purposes. More sophisticated instrumental methods including spectroscopy and chromatography, in combination with multivariate analysis-chemometrics, can be used to determine food authenticity, identify adulterations or mislabeling and determine food safety. The purpose of this review is to present the current state of knowledge on the use of chemometric tools for evaluating quality of food products of animal and plant origin and beverages. The article describes applications of several multivariate techniques in food and beverages research, showing their role in adulteration detection, authentication, quality control, differentiation of samples and comparing their classification and prediction ability.

Characterization of Chinese Unifloral Honeys Based on Proline and Phenolic Content as Markers of Botanical Origin, Using Multivariate Analysis

The phenolic and proline content were determined in honey samples of different floral origins (rapeseed, sunflower, buckwheat and Codonopsis) from five different regions of China. The phenolic and proline profile of these samples were used to construct a statistical model to distinguish honeys from different floral origins. Significant differences were identified among the studied honey samples from multivariate chemometric methods. The proline content varied among the four types of honeys, with the values decreasing in the order: buckwheat > Codonopsis > sunflower > rapeseed. Rapeseed honeys contained a high level of benzoic acid, while rutin, p-coumaric acid, p-hydroxybenzoic acid were present at relatively high levels in buckwheat honeys. Principal component analysis (PCA) revealed that rapeseed honey could be distinguished from the other three unifloral honeys, and benzoic acid, proline and kaempferol could serve as potential floral markers. Using 18 phenolic compounds and proline the honey samples were satisfactorily classified according to floral origin at 94% correct prediction by linear discriminant analysis (LDA). The results indicated that phenolic compounds and proline were useful for the identification of the floral origin of the four type honeys.

Strategy for comparative untargeted metabolomics reveals honey markers of different floral and geographic origins using ultrahigh-performance liquid chromatography-hybrid quadrupole-orbitrap mass spectrometry

Honey discrimination based on floral and geographic origins is limited by the ability to determine reliable markers because developing hypothetical substances in advance considerably limits the throughput of metabolomics studies. Here, we present a novel approach to screen and elucidate honey markers based on comparative untargeted metabolomics using ultrahigh-performance liquid chromatography-hybrid quadrupole-orbitrap mass spectrometry (UHPLC-Q-Orbitrap). To reduce metabolite information losses during sample preparation, the honey samples were dissolved in water and centrifuged to remove insoluble particles prior to UHPLC-Q-Orbitrap analysis in positive and negative electrospray ionization modes. The data were pretreated using background subtraction, chromatographic peak extraction, normalization, transformation and scaling to remove interferences from unwanted biases and variance in the experimental data. The pretreated data were further processed using principal component analysis (PCA) and a three-stage approach (t-test, volcano plot and variable importance in projection (VIP) plot) to ensure marker authenticity. A correlation between the molecular and fragment ions with a mass accuracy of less than 1.0ppm was used to annotate and elucidate the marker structures, and the marker responses in real samples were used to confirm the effectiveness of the honey discrimination. Moreover, we evaluated the data quality using blank and quality control (QC) samples based on PCA clustering, retention times, normalized levels and peak areas. This strategy will help guide standardized, comparative untargeted metabolomics studies of honey and other agro-products from different floral and geographic origins.

Comprehensive Profiling of Phytohormones in Honey by Sequential Liquid-Liquid Extraction Coupled with Liquid Chromatography-Mass Spectrometry

Honey exhibits various nutritional and medicinal functions, which are highly related to the active components; thus, the exploration of new compounds in honey is of great importance. Because honey is a byproduct of flower nectar, which is rich in phytohormones, the existence of phytohormones in honey is anticipated. In this research, a method for comprehensive profiling of 49 phytohormones in honey was developed by sequential liquid-liquid extraction (LLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Good linearities for 49 phytohormones were obtained with correlation coefficients (R) larger than 0.9913. The limits of detection (LODs) were in the range of 0.2-628.2 pg/mL. Satisfied reproducibility and reliability were achieved by evaluation of the intra- and interday precisions with relative standard deviations (RSDs) less than 15.8% and relative recoveries ranging from 80.4 to 123.7%. The method was further applied to analyze the phytohormones in 14 monofloral raw honey samples and 3 commercial honey samples. The existence of 34 phytohormones was confirmed, including 14 cytokinins (CKs), 8 gibberellins (GAs), 5 brassinosteroids (BRs), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), jasmonoyl-leucine (JA-Leu), and jasmonoyl-phenylalanine (JA-Phe). In addition, the content and species of phytohormones varies in different kinds of honey. The study is beneficial to fully illustrate the phytohormone profile of honey and contributive to elucidate the mechanism of its nutritional and medicinal functions.