Floral Origin Of Honey Research Articles

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.

Evaluating the Antioxidant Properties of Unifloral Honey (Apis mellifera L.) from Ethiopia.

The antioxidant properties of natural honey primarily rely on the floral origin from which nectar is collected by bees. Thus, the current activity evaluated the antioxidant properties of honey based on its floral type. The honey floral origin was verified by the melissopalynological technique. Antioxidant properties were determined by using standard procedures and analyzed by SAS. Six unifloral honey types with their harvesting month were identified. Accordingly, Guizotia (74% of pollen frequency), Coffea arabica (68%), Vernonia (90%), Croton macrostachyus (64%), Schefflera abyssinica (100%), and Eucalyptus (100%) were cropped in November, February, February, May, April, and June separately. Statistically, a variation (p < 0.05) in antioxidant parameters was displayed between unifloral honeys. Vernonia honey exhibited the maximum total phenol (77.2 ± 0.7), total flavonoid (65.0 ± 3.8), and total antioxidant content (65.4 ± 0.3). On the other hand, S. abyssinica honey recorded the least total phenol content (24.1 ± 0.4), total flavonoid content (18.6 ± 2.7), and total antioxidant content (5.6 ± 0.5). Statistical analysis showed a positive correlation between all the tested antioxidant parameters. Thus, the current study indicated that all the tested Ethiopian unifloral honey had good sources of antioxidants with the most Vernonia honey followed by C. macrostachyus whereas S. abyssinica honey had the least followed by Eucalyptus.

Phenolic compounds in Hungarian acacia, linden, milkweed and goldenrod honeys

Honey is a valuable source of nutrients, minerals and phenolic compounds. Phenolic acids and flavonoids are associated with health benefits of honey and can serve as markers for distinguishing honey types. This study aimed at determining the phenolic profile of four Hungarian unifloral honeys that were not analyzed previously. After verifying their botanical origin with melissopalynological analysis, total reducing capacity was determined with Folin-Ciocalteau method, and phenolic composition was analyzed with HPLC-DAD-MS. From the 25 phenolic substances examined, pinobanksin was the most abundant, followed by chrysin, p-hydroxybenzoic acid and galangin. Quercetin and p-syringaldehyde were detected only in acacia honey, which contained higher levels of chrysin and hesperetin compared to the other three honeys. Milkweed and linden honeys displayed higher levels of caffeic, chlorogenic, ferulic and p-coumaric acids compared to acacia and goldenrod honeys. Taxifolin may serve as a unique marker compound of milkweed honey. Goldenrod honey contained the highest level of syringic acid. Principal component analysis supported the indicator role of polyphenols in honey identification, discriminating clearly the four unifloral honeys. Our results suggest that phenolic profiles may be useful to find markers of honey's floral origin, but geographical origin can strongly influence the composition of characteristic compounds.

Assessment of the botanical origin of Bulgarian honey samples using melissopalynological, DNA barcoding and NMR analyses

Polyfloral honey samples from Bulgaria were subject to parallel analyses of their botanical origin and composition using traditional melissopalynology, DNA barcoding based on the plastid rbcL gene and NMR analysis. The obtained datasets were compared with each other to evaluate the information capacity of the applied experimental methods. The results from the melissopalynological and DNA-barcoding studies demonstrated a significantly higher resolution of the latter, revealing the presence of pollen from a total of 17 plant families, 21 plant genera and 5 plant species in comparison to pollen from only 7 plant families, 3 plant genera and 4 plant species identified by melissopalynology. The higher resolution of DNA barcoding allows a more detailed characterisation of the diet and foraging preferences of honey bees, including foraging on plant species growing in lower abundance in the area. The comparison of the quantitative data on floral honey composition for several plant genera and species reveals significant differences between the relative abundance of the pollen grains estimated by melissopalynological analysis and the relative abundance of rbcL clones in rbcL libraries determined after DNA barcoding. All three applied methods confirm the polyfloral botanical origin of the analysed samples and support routine NMR use for the assessment of the floral origin of honey.

The antimicrobial mechanism of Greek thyme honeys against methicillin‐resistant Staphylococcus aureus clinical isolates: a case study of comparison with Manuka honey

SummaryThe antibacterial potential of honey has been of great scientific interest. Understanding the underlying mechanism is essential to explore its potential as therapeutic alternative against a range of (non)pathogenic microorganisms. The floral origin of honey is critical for its antibacterial activity and Greek thyme honeys have been of increasing interest due to their chemical composition and bioactivity. In this study, the antimicrobial effect of six Greek honeys, with different percentages of thyme pollen grains and two Manuka honeys were tested against four MRSA clinical isolates (ATCC 43300, 0791, 28965, 01322). Agar‐well diffusion assay and total viable counts were used to examine the antimicrobial strength of honeys, while the effect thereof on cellular redox state and cell membrane was tested by flow cytometry. Thyme honeys had superior or equal antimicrobial strength compared to this of Manuka, while thermal processing did not significantly affect this activity. Acidity and the high H2O2 content, common features for all thyme honeys, caused cellular oxidative damage and cell death unlike observed in Manuka‐treated populations. The activity of the monofloral thyme honey (74% thyme pollen) was higher than the other indigenous polyfloral samples, which confirms the medicinal importance of this medicinal plant.

Classification of Unifloral Honeys from SARDINIA (Italy) by ATR-FTIR Spectroscopy and Random Forest.

Nowadays, the mislabeling of honey floral origin is a very common fraudulent practice. The scientific community is intensifying its efforts to provide the bodies responsible for controlling the authenticity of honey with fast and reliable analytical protocols. In this study, the classification of various monofloral honeys from Sardinia, Italy, was attempted by means of ATR-FTIR spectroscopy and random forest. Four different floral origins were considered: strawberry-tree (Arbutus Unedo L.), asphodel (Asphodelus microcarpus), thistle (Galactites tormentosa), and eucalyptus (Eucalyptus calmadulensis). Training a random forest on the infrared spectra allowed achieving an average accuracy of 87% in a cross-validation setting. The identification of the significant wavenumbers revealed the important role played by the region 1540–1175 cm−1 and, to a lesser extent, the region 1700–1600 cm−1. The contribution of the phenolic fraction was identified as the main responsible for this observation.

Determination of the floral origin of honey based on its phenolic profile and physicochemical properties coupled with chemometrics

ABSTRACT Adulteration of honey is a major problem in the food industry. The purpose of the present study was to classify different types of monofloral honey based on physicochemical characterization and analysis of phenolic compounds coupled with chemometrics methods. The methods for classification were trialed on a wide range of honey samples from different floral origins. For thyme, jujube, coriander, barberry, acacia and alfalfa honey samples, principal component analysis combined with discriminant analysis (PCA-DA) and partial least squares combined with discriminant analysis (PLS-DA) were trialed. The results indicate that the botanical origin of the honey affects the profile of flavonoids and phenolic compounds. For example, jujube honey samples had the highest amounts of hesperetin and chrysin, while thyme honey had the maximum amount of caffeic acid; the highest levels of quercetin and p-coumaric acid were found in coriander honey. To reduce the numbers of independent variables for modeling, the principal component analysis (PCA) algorithm was used. The three scores extracted from PCA had 83.17% variance. The classification results show that PLS-DA was successfully used to predict the class membership of honey samples (100%), but PCA-DA gave the lowest correct classification rate (97%).

Preliminary Study on Effect of Agricultural Activities in Pollen Spectrum of Argentinean Honey

Abstract Honey floral origin is determined by the harversting region, but anthropogenic factors as agriculture expansion might modify the environmental flora and consequently honey floral origin. Argentina is one of the most important honey producers worldwide which, since the 1990s, has undergone an important agriculture transformation by the adoption of transgenic crops like soybean (Glycine max). However, little is known about the effects of this anthropogenic activity on the floral origin of honey or the statistical tools that could be used to analyse it. The objective of the present study was to evaluate the impact that these environmental modifications have on the pollen spectrum of honey. In order to achieve this, thirty-two samples of blossom honey were collected from three different ecoregions of the Buenos Aires province: Parana Delta and Islands, Espinal and Pampa, in two different years: 1999 and 2014. The pollen spectrum of honey samples was determined and the data obtained was analysed with multivariate statistical techniques. It could be concluded that the pollen composition of honeys from different ecoregions has significantly changed in the past years because of agriculture expansion and adaptation of transgenic crops (p=0.007). Honey samples harvested in 1999 were characterized by high values of Helianthus annuus, while in 2014 an important presence of Eryngium sp., Gleditsia triacanthos, Baccharis type, Trifolium sp. and Glycine max was observed. The present results show that honey palynological results and multivariate statistical analysis could be used as a preliminary attempt to evaluate environmental modifications.

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

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. 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. 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. 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. 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.

Discrimination of Clover and Citrus Honeys from Egypt According to Floral Type Using Easily Assessable Physicochemical Parameters and Discriminant Analysis: An External Validation of the Chemometric Approach.

Twenty-two honey samples, namely clover and citrus honeys, were collected from the greater Cairo area during the harvesting year 2014–2015. The main purpose of the present study was to characterize the aforementioned honey types and to investigate whether the use of easily assessable physicochemical parameters, including color attributes in combination with chemometrics, could differentiate honey floral origin. Parameters taken into account were: pH, electrical conductivity, ash, free acidity, lactonic acidity, total acidity, moisture content, total sugars (degrees Brix-°Bx), total dissolved solids and their ratio to total acidity, salinity, CIELAB color parameters, along with browning index values. Results showed that all honey samples analyzed met the European quality standards set for honey and had variations in the aforementioned physicochemical parameters depending on floral origin. Application of linear discriminant analysis showed that eight physicochemical parameters, including color, could classify Egyptian honeys according to floral origin (p < 0.05). Correct classification rate was 95.5% using the original method and 90.9% using the cross validation method. The discriminatory ability of the developed model was further validated using unknown honey samples. The overall correct classification rate was not affected. Specific physicochemical parameter analysis in combination with chemometrics has the potential to enhance the differences in floral honeys produced in a given geographical zone.

Voltammetric sensor for electrochemical determination of the floral origin of honey based on a zinc oxide nanoparticle modified carbon paste electrode

Abstract. A new methodology based on cyclic voltammetry using a chemically modified electrode has been developed for the discrimination of the floral origin of honey. This method involves an electronic tongue with an electrochemical sensor made from a carbon paste (CPs) electrode where zinc oxide (ZnO) nanoparticles are used as an electroactive binder material. The bare CPs electrode is evaluated for comparison. The electrochemical response of the modified electrode in 50 samples of five different floral types of honey has been analysed by the cyclic voltammetric technique. The voltammograms of each floral variety of honey reflect the redox properties of the ZnO nanoparticles present inside the carbon paste matrix and are strongly influenced by the nectar source of honey. Thus, each type of honey provides a characteristic signal which is evaluated by using principal component analysis (PCA) and an artificial neural network (ANN). The result of a PCA score plot of the transient responses obtained from the modified carbon paste electrode clearly shows discrimination among the different floral types of honey. The ANN model for floral classification of honey shows more than 90 % accuracy. These results indicate that the ZnO nanoparticles modified carbon paste (ZnO Nps modified CPs) electrode can be a useful electrode for discrimination of honey samples from different floral origins.

VIS/NIR imaging application for honey floral origin determination

Nondestructive methods are of utmost importance for honey characterization. This study investigates the potential application of VIS-NIR hyperspectral imaging for detection of honey flower origin using machine learning techniques. Hyperspectral images of 52 honey samples were taken in transmittance mode in the visible/near infrared (VIS-NIR) range (400–1000nm). Three different machine learning algorithms were implemented to predict honey floral origin using honey spectral images. These methods, included radial basis function (RBF) network, support vector machine (SVM), and random forest (RF). Principal component analysis (PCA) was also exploited for dimensionality reduction. According to the obtained results, the best classifier (RBF) achieved a precision of 94% in a fivefold cross validation experiment using only the first two PCs. Mapping of the classifier results to the test set images showed 90% accuracy for honey images. Three types of honey including buckwheat, rapeseed and heather were classified with 100% accuracy. The proposed approach has great potential for honey floral origin detection. As some other honey properties can also be predicted using image features, in addition to floral origin detection, this method may be applied to predict other honey characteristics.

Near infrared spectroscopy applied to the rapid prediction of the floral origin and mineral content of honeys

Consumers demand to know the floral origins of honeys. Therefore, the use of simple and reliable techniques for differentiating among honeys by their origins is necessary. Multivariate statistical techniques and near infrared spectroscopy applied to palynological and mineral characteristics make it possible to differentiate among the types of honey collected from Northwestern Spain. Prediction models using a modified partial least squares regression for the main pollen types (Castanea, Eucalyptus, Rubus and Erica) in honeys and their mineral composition (potassium, calcium, magnesium and phosphorus) were established. Good multiple correlation coefficients (higher than 0.700) and acceptable standard errors of cross-validation were obtained. The ratio performance deviation exhibited a good prediction capacity for Rubus pollen and for Castanea pollen, whereas for minerals, for Eucalyptus pollen and for Erica pollen the ratio performance deviation was excellent. Near infrared spectroscopy was established as a rapid and effective tool to obtain equations of prediction that contribute to the honey typification.

Impedance spectroscopy for rapid determination of honey floral origin

In this work electrical impedance spectroscopy was applied as an alternative method for floral origin determination of unifloral honeys, which may supplement the labeling according to the European Legislation. Impedance measurements, in agreement with data from routine analyses, allowed to distinguish the unifloral honey samples and to acquire information on chemical and physical properties, such as conductivity, ash content and acidity. Equivalent electrical circuits have been extracted for each unifloral honey sample, which have been validated by means of electrical simulation, and every electrical component has been associated to a specific honey characteristic. It can be concluded that the method developed here permits rapid and easy determination of honey floral origin, no sample preparation procedure is required and it could be used in the official control laboratories.

Identification of monofloral honey using voltammetric electronic tongue

Quality assessment of honey is often related to its floral origin which is a complex task to evaluate. Traditional technique of floral assessment is made by melissopalynological method. However, this method is quite time consuming and also often operator dependent. Thus, the fallout is a large range of error in interpretation of the result and hence there is considerable demand for instrumental methods to assess the identification of pollen in honey. In this pursuit, an electronic tongue based on cyclic voltammetry is developed to discriminate honey samples based on their floral types and is described in this paper. The technique has been investigated using platinum as the working electrode and the resultant current from the potentiostat has been considered for data analysis. The use of principal component analysis (PCA) and linear discriminate analysis (LDA) proves to be useful in clustering honey samples. Finally, classification performances are investigated using back-propagation multilayer perceptron (BP-MLP) and radial basis function (RBF) neural network models for identification of different floral origin of honey.

Comprehensive Study of Honey with Protected Denomination of Origin and Contribution to the Enhancement of Legal Specifications

In this study the characterization of a total of 60 honey samples with Protected Denomination of Origin (PDO) collected over three harvests (2009–2011, inclusive), from the Northeast of Portugal was carried out based on the presence of pollen, physicochemical and microbiological characteristics. All samples were found to meet the European Legislation, but some didn’t meet the requirements of the PDO specifications. Concerning the floral origin of honey, our results showed the prevalence of rosemary (Lavandula pedunculata) pollen. The microbiological quality of all the analyzed samples was satisfactory, since fecal coliforms, sulfite-reducing clostridia and Salmonella were absent, and molds and yeasts were detected in low counts. Significant differences between the results were studied using one-way analysis of variance (ANOVA), followed by Tukey’s HSD test. The samples were submitted to discriminant function analysis, in order to determine which variables differentiate between two or more naturally occurring groups (Forward Stepwise Analysis). The variables selected were in this order: diastase activity, pH, reducing sugars, free acidity and HMF. The pollen spectrum has perfect discriminatory power. This is the first study in which a honey with PDO was tested, in order to assess its compliance with the PDO book of specifications.

Determination of the floral origin of some Romanian honeys on the basis of physical and biochemical properties

The aim of this study was to determine the physical and biochemical properties of some Romanian honeys in order to discriminate between their floral origins. The evaluated properties were total phenolic content, total protein content, total free amino acids content, color intensity (ABS450), pH, ash content, antioxidant activity. Twenty-six commercial honeys from six types of flowers (acacia, sunflower, forest, polyfloral, lime and Sea Buckthorn) were investigated. All samples showed considerable variations with reference to their properties. The properties values were in the range of approved limits (according to EU legislation). The total phenolic, total protein and total free amino acids contents and color intensity varied considerably. Similarly, forest honey had the highest antioxidant activity while the lowest was found in acacia honey. Correlation between the floral origin of honeys and the physical and biochemical properties, respectively, was observed. Moreover, this study demonstrates remarkable variation in DPPH scavenging activity and content of total phenols in honey, depending on its botanic source.

Characterization of Monofloral Honeys with Multivariate Analysis of Their Chemical Profile and Antioxidant Activity

Various bioactive chemical constituents were quantified for 21 honey samples obtained at Rio de Janeiro and Minas Gerais, Brazil. To evaluate their antioxidant activity, 3 different methods were used: the ferric reducing antioxidant power, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, and the 2,2'-azinobis (3-ethylbenzothiazolin)-6-sulfonate (ABTS) assays. Correlations between the parameters were statistically significant (-0.6684 ≤ r ≤-0.8410, P < 0.05). Principal component analysis showed that honey samples from the same floral origins had more similar profiles, which made it possible to group the eucalyptus, morrão de candeia, and cambara honey samples in 3 distinct areas, while cluster analysis could separate the artificial honey from the floral honeys. This research might aid in the discrimination of honey floral origin, by using simple analytical methods in association with multivariate analysis, which could also show a great difference among floral honeys and artificial honey, indicating a possible way to help with the identification of artificial honeys.

Variaciones en la flora apícola de una región de la Depresión del Salado (Buenos Aires, Argentina) referidas a cambios ambientales asociados con humedales. Implicancia económica

A study of the pollen present in honey from an apiary located in the area of the Depresion del Salado, Buenos Aires, Argentina, in order to observe the plants used by Apis mellifera L. in an environment that has been affected by periodic floods that changed the vegetation, and making comparisons with existing data. Thirty one pollen types belonging to fifteen botanical families were identified. All samples were monofloral of Lotus tenuis with high percentages, above 50%. The results show significant variation respect to previous data on resources used by the honeybee in this area. It makes a new contribution to knowledge of the floral origin of honey from the region that will affect their commercial value.

OPTIMIZATION OF A HS‐SPME/GC‐MS METHOD FOR DETERMINATION OF VOLATILE COMPOUNDS IN SOME CUBAN UNIFLORAL HONEYS

ABSTRACT A headspace (HS)/solid phase microextraction (SPME)/gas chromatography‐mass spectrometry (GC‐MS) method was developed to determine the profiles of volatile compounds from three Cuban unifloral honeys: Turbina corymbosa (L.) Raf., Ipomoea triloba L. and Gouania polygama (Jacq.) Urb. The optimization of the extraction conditions was carried out by response surface methodology. The analytical conditions of the optimized HS‐SPME method were: 65 µm PDMS/DVB fiber, 6 g honey, 3 mL water and 20% w/w sodium chloride, 20 min for pre‐extraction, 30 min for extraction at 60C and 4 min for GC desorption. The GC‐MS analysis allowed the identification of 181 volatile compounds in these honeys. Possible markers for the floral classification of honeys were for the T. corymbosa type: 4‐methyl methoxysalicylate, trans‐pinocarveol, chavicol, methyl anisate, trans‐α‐bergamotene and α‐bisabolol. In I. triloba honey, 2,5,5‐trimethyl‐3‐tetrahydrofuranone and 1,2‐diphenylethanol were found, while4‐methyl‐1‐pentanol and isopentyl acetate were only present in G. polygama honey. With the use of the HS‐SPME method in combination with multivariate analysis techniques such as Principal Component Analysis and K‐nearest neighbor, it was possible to discriminate the different honeys according to their floral origin.PRACTICAL APPLICATIONSHoney is a natural product produced by Apis mellifera bees from nectar and secretions of the living parts of the plants. According to the nectar source, honeys can be multifloral (nectars from diverse flowers) or unifloral (nectar from only one flower). The floral origin of honey is an important characteristic in the evaluation of its quality. Control and characterization of the volatile compounds of unifloral honeys is highly important in Cuban apiculture, and has not been carried out so far. The objective of this work was to develop and optimize a method to determine origin of some Cuban unifloral honeys, by means of a headspace‐solid phase microextraction.