Blossom Honey Research Articles

Direct determination of the total concentrations of copper, iron and manganese and their fractionation forms in freshly ripened honeys by means of flame atomic absorption spectrometry

The objective of this work was to evaluate the suitability of the direct analysis of honey with flame atomic absorption spectrometry (FAAS) for the total concentrations of Cu, Fe and Mn. The sample treatment included only the simple dissolution of the samples in water. It was found to be precise and reliable, and was applied to the determination of Cu, Fe and Mn in light to yellow color ripened blossom honeys. The precision (1.7–6.2% for Cu, 1.9–5.9% for Fe and 1.9–8.8% for Mn) and the accuracy (from −4.3 to +2.2% for Cu, from −2.6 to +0.3% for Fe and from −2.8 to +1.1% for Mn) achieved with this method is satisfactory for that kind of analysis. In addition, the fractionation patterns for Cu, Fe and Mn in these honeys were assessed using a fractionation scheme based on two-column solid phase extraction (SPE) with an apolar adsorbent Amberlite XAD-16 and a strong cation exchanger Dowex 50W-x8-200. With this procedure it was possible to separate three operationally defined classes of Cu, Fe and Mn species present in honeys, i.e., the hydrophobic, the cationic and the residual metal species containing fractions. Regarding the total concentrations of Cu, Fe and Mn in the analyzed blossom honeys, it was found that the most abundant group of the metal species is the cationic fraction, contributing up to 61%, 74% and 89% of Cu, Fe and Mn, respectively.

The application of Taguchi method to determine the optimum blend of unifloral honeys to most closely match thyme honey quality

SummaryThis study was conducted to investigate the effect of four blossom honey types (orange, chestnut, heather and cotton) on a group of quality characteristics of thyme‐type based mixture preparations. Mixture ratios were prepared at 0%, 50% and 100% per blossom honey‐type and then were blended with thyme honey in parts 1:1. The melissopalynological, sensory and physicochemical quality characteristics for each blend were monitored. A three‐level, four‐factor orthogonal array according to the Taguchi method was utilised to plan the experiments maintaining the thyme component as a ‘slack‐variable’ to contain the number of performed trials. Subsequent anova treatment revealed that only a pure orange‐type blend favours the simultaneous maximisation of aroma (P < 0.05) and the minimisation of electrical conductivity (P < 0.05). Finally, there was a significant effect of chestnut‐type blend content on microscopical and physicochemical characteristics (P < 0.05), nevertheless, their corresponding signal‐to‐noise ratios are maximised only at a concentration of zero value.

Methyl Syringate: A Chemical Marker of Asphodel (Asphodelus microcarpus Salzm. et Viv.) Monofloral Honey

During the liquid chromatographic study of the phenolic fraction of monofloral honeys was detected in the asphodel honey ( Asphodelus microcarpus Salzm. et Viv.) chromatogram a distinctive peak not detected in other monofloral honeys such as Arbutus unedo L., Hedysarum coronarium , Eucalyptus spp., and Galactites tomentosa . After thin layer chromatography (TLC) purification and characterization by NMR and LC-MS/MS, the compound was identified as methyl syringate (MSYR) and confirmed against an original standard. Levels of MSYR were measured in honeys of 2005, 2006, and 2007 by HPLC-DAD analysis. Level determination of MSYR was repeated in 2008 for 2006 and 2007 honeys to evaluate chemical stability of this phenolic compound. Levels of MSYR measured 1 year after the sampling did not show significant statistical differences (p < 0.05). The stability of MSYR was also confirmed by 12 asphodel honey samples collected in 2005 that showed amounts of methyl syringate comparable with those found in fresh honey. For the evaluation of MSYR origin, samples of nectars were collected from flowers and the content of MSYR was measured. Levels of MSYR in honeys are originated from the nectar with an average contribution of the nectar to the honey of 80%. Melissopalinological analysis did not allow the attribution of the honey monofloral origin because levels of asphodel pollen were <6% for all analyzed samples. Previously reported levels of MSYR for robinia, rape, chestnut, clover, linden blossom, dandelion, sunflower, thyme, manuka, and fir honeys were <5 mg/kg. For this reason, a minimum level of 122.6 mg/kg for MSYR in asphodel honeys can be considered as a chemical marker and, unlike the melissopalynological analysis, can be used for the origin attribution and to evaluate the percent of asphodel nectar in the honey.

Environmental concentration of selected elements and relation to physicochemical parameters in honey

The purpose of this study was to evaluate the content of selected elements and physicochemical indicators of the honey of Apis mellifera. Samples of blossom, blend and honeydew honeys were randomly obtained from the Eastern, Western and Central of Slovakia. Contents of elements were measured with the use of flame atomic absorption spectrophotometry (FAAS) method and anodic stripping voltammetry (ASV) method with CGMDE as working electrode. The content of heavy metals (mg/kg dry weight) ranged as follows: Zn 0.25–3.82; Cu 0.12–1.37; Ni 0.06–0.60; Mg 0.10–50.43; Ca 10.32–87.21; Pb and Cd were under detectable limit (0.001 mg/kg). The physical and chemical indicators ranged as follows: moisture (%) 16.00–19.80; HMF (mg/kg) 10.00–40.00; pH 3.58–5.12; conductivity (mS/m) 13.45–99.12 and a w 0.456–0.659. Significant difference (P < 0.05) for elements and physicochemical indicators was analyzed. Significant correlations between Cu – Zn, Cu – Ni, Cu – Mg, Ca – Zn and Ca – Mg were detected. With reference to Codex Alimentarius of Slovakia, maximal levels of heavy metals content and selected physicochemical properties were not exceeded. On average, the content of trace elements decreased in the order: Ca > Mg > Zn > Cu > Ni and physicochemical indicators decreased: conductivity > HMF > moisture > pH > aw.

Typing ofPantoea agglomeransisolated from colonies of honey bees (Apis mellifera) and culturability of selected strains from honey

Pantoea agglomerans is a possible biocontrol agent against fire blight (Erwinia amylovora) and a facultative pathogen of humans. Isolates were gathered from flowers, pollen loads, honey sacs, and freshly stored nectar (FSN). Under artificial inoculation conditions, strains completely lost their culturability at 24 °C after 120 h of incubation in honey and 156 h in honey solution, respectively. None of tested strains could be cultivated from FSN, honey, or honey solution after 48 h at temperatures higher then 28 °C. At different time intervals, culturable population levels at 35 °C and 24 °C were significantly higher in blossom honey or its solution than in blossom and honeydew honey or its solution. Our results indicated that P. agglomerans is widely spread throughout honey bee’s environment. Strains lost culturability after short periods of incubation in honey or honey solution. In samples of honey and royal jelly from test colonies, no culturable P. agglomerans isolates could be detected.

The Investigation of Protein Prophile of Different Botanic Origin Honey and Density Saccharose- Adulterated Honey by SDS-PAGE Method

Summary Protein content and quality of honeys are varied according to the plant source as well as production and handling conditions. Lots of methods were developed to determine the botanical origins and qualities of honeys. The aim of this study was to comparatively evaluate the protein profiles of the honeys produced from bee colonies exposed to different plant sources (rhododendron, chestnut, blossom, pine) and feeding (Saccharose nutrition) conditions by using SDS-PAGE method. In this study, the protein profiles, but not protein densities, were found similar between pure honeys produced from rhododendron, chestnut, blossom, pine and high sugared (saccharose) honeys. Three main protein bands (94 kDa, 87 kDa and 84 kDa) were determined in the electrophoretic analysis of the honeys. Protein ratios (%) were determined as 1.31±0.07, 1.02±0.04, 0.90±0.03, 1.16±0.09 and 0.23±0.01, respectively. Protein band densities were found higher in rhododendron, chestnut and pine honeys than those in honeys produced by using excessive saccharose syrup. It was concluded that protein profile can be used in differentiation between pure and adulterated honeys.

High-performance liquid chromatographic analysis of sugars in Transylvanian honeydew honey.

declared honeydew honey samples were collected from different Transylvanian areas. Origin of the samples was verified by physico-chemi cal parameters and pollen analysis. Their sugar pro file was analysed by means of HPLC with refractive index detection. The results obtained showed that only 25% o f the samples correspond to the requirements of honeydew honey. The rest of 75% samples were mixed blossom- honeydew or pure blossom honeys. Our principal objective was the determination of sugar profile for Transylvanian honeydew honey.

ESSENTIAL OILS OF FLOWERS OF CITRUS SINENSIS AND CITRUS CLEMENTINA CULTIVATED IN ALGARVE, PORTUGAL

ESSENTIAL OILS OF FLOWERS OF CITRUS SINENSIS AND CITRUS CLEMENTINA CULTIVATED IN ALGARVE, PORTUGAL

Verification test of sensory analyses of comb and strained honeys produced as pure and feeding intensively with sucrose (Saccharum officinarum L.) syrup

The aims of the study were to discriminate comb and strained honeys produced by the standard beekeeping method (control), shaking method (pure blossom honey), and feeding intensively (100kg/colony) with sucrose (adulterated honey) syrup by using sensory analysis and to develop a method to be used in identification of unknown or suspicion honey samples. In the study, twenty trained panelists assessed honey samples in relation to their properties including taste, odor, color, aroma, viscosity, dissolution in mouth, inflammation in throat, attractiveness, flavor and general impression during four months. There were no differences in odor, viscosity, and dissolution in mouth between comb and strained honey samples which produced by different methods (P > 0.05). Discrimination of strained honey by sensory analysis was more reliable when compared to comb honey. The ratio of correctly classified sample was 78.3% for comb and 86.7% for strained honey. The more honey was pure the more discrimination of honey sample by sensory analysis was reliable. In verification test five unknown honey samples were classified 100% in their real groups by using canonical discriminant function Coefficients of each properties evaluated and the projections of the sample points on the plane of the canonical function-1 and function-2.

Determination of important biochemical properties of honey to discriminate pure and adulterated honey with sucrose ( Saccharum officinarum L.) syrup

The aims of the present study were to determine biochemical properties of honey samples and to discriminate pure and adulterated honey produced by the standard bee feeding method (control honey), the shaking method (pure blossom honey), and overfeeding (100 kg/colony syrup) with sucrose syrup (adulterated honey). The biochemical properties evaluated were moisture, ash, acidity, hydroxymethylfurfural (HMF), specific sugars (i.e. fructose, glucose, fructose–glucose, sucrose, and maltose), diastase activity, δ 13C value (honey), δ 13C value (protein), electrical conductivity, potassium, vitamin C, and proline. Fifteen honey samples were analyzed by discriminant analysis stepwise method. Proline, electrical conductivity and sucrose were found as discriminative characters of samples. Based on these three properties 100% of original group cases (samples) correctly classified in their real group. We found that the honey produced by feeding with 100 kg sucrose syrup per colony contained the sucrose as low as pure blossom honey. Therefore, the sugar (sucrose, fructose and glucose) content of honey cannot be used to distinguish between adulterated (sucrose syrup) and pure blossom honey.

Authentication of the Botanical Origin of Honey by Near-Infrared Spectroscopy

Fourier transform near-infrared spectroscopy (FT-NIR) was evaluated for the authentication of eight unifloral and polyfloral honey types (n = 364 samples) previously classified using traditional methods such as chemical, pollen, and sensory analysis. Chemometric evaluation of the spectra was carried out by applying principal component analysis and linear discriminant analysis. The corresponding error rates were calculated according to Bayes' theorem. NIR spectroscopy enabled a reliable discrimination of acacia, chestnut, and fir honeydew honey from the other unifloral and polyfloral honey types studied. The error rates ranged from <0.1 to 6.3% depending on the honey type. NIR proved also to be useful for the classification of blossom and honeydew honeys. The results demonstrate that near-infrared spectrometry is a valuable, rapid, and nondestructive tool for the authentication of the above-mentioned honeys, but not for all varieties studied.

Physicochemical properties and pollen spectrum of imported and local samples of blossom honey from the Pakistani market

SummaryFifteen samples of different geographical origin including Pakistan were analysed for density, ash, water content, electrical conductivity, total acidity, pH, total solid, hydroxylmethylfurfural (HMF), minerals and trace metals. The physicochemical parameters were found to be within acceptable ranges (specific gravity 1.40–1.46, ash 0.03–0.21%, moisture 15.6–19.2, total solid 78.7–81.4%, free acidity 23.55–58.52 meq kg−1, conductivity 0.27–0.37 mS cm−1, pH 3.29–4.05, viscosity 33.4–136.4 poise). However, the analysis of HMF showed that imported samples were either exposed to a high temperature during processing or were overage. Greater attention is required, therefore, in the analysis of HMF and in deciding the shelf life, particularly for the imported samples before marketing. Pollen analysis revealed that all the analysed samples were of a multifloral type. All the data were statistically tested using principal component analysis (PCA) with the aim of characterizing the honeys and identifying the most significant parameters in the analysed samples.

Gas chromatographic detection of d-amino acids in natural and thermally treated bee honeys and studies on the mechanism of their formation as result of the Maillard reaction

Relative quantities of d-amino acids, (%D) calculated from the sum of d- and l-amino acids were determined in bee honeys (n=6) by GC-SIM-MS. Amino acids were isolated by treatment with Dowex 50 W X8 cation exchanger and converted into N(O)-perfluoroacyl amino acid propyl esters. In all honeys d-Ala, ranging from 2.2–6.2% d-Ala, was detected. Other d-amino acids were also found, albeit not in all honeys and approached 5.9% d-Glx, 5.4% d-Lys, 3.0% d-Phe, 2.1% d-Orn, 1.7% d-Asx, 1.5% d-Ser, 0.1% d-Pro, and 0.4% d-Val in certain honeys. Quantities of d-amino acids increased very much on experimental heating of honeys in an oven and on a microwave treatment. Conventional heating of a forest honey (no. 1) at 65 °C for 450 h leads to an increase of d-Ala (2.2–12.5%), d-Pro (0.0–5.0%), d-Ser (1.5–9.1%), d-Asx (1.7–9.8%), d-Phe (0.4–5.0%) and d-Glx (1.5–5.8%); first numbers in parentheses refer to unheated honeys. Relative quantities of other d-amino acids also increased. Experimental heating of another forest honey (no. 2) in a microwave oven for 3 min at 180 W leads to an increase of d-Ala (3.7–11.0%), d-Glx (1.5–13.7%), d-Asx (0.7–10.2%), d-Phe (0.3–4.8%), d-Val (0–4.2%), and d-Pro (0.1–2.3%). Microwave treatment at 700 W for 1 min of a blossom honey (no. 3) leads to an increase of d-Ala (6.2–26.7%) and of d-Phe (3.0–10.9%). Microwave treatments were accompanied by intensive destruction of amino acids. Heating of a model mixture mimicking the major components of honey (d-glucose, d-fructose, and l-amino acids at 20% water content) at pH 2.6–9.0 and at 180 W for 1–3 min leads to the generation of d-amino acids and was also accompanied by intensive decay of amino acids. From the data it is concluded that d-amino acids are formed in honeys in the course of the Maillard reaction. A mechanism is presented based on amino acid racemization of reversibly formed Heyns and Amadori compounds (fructose-amino acids).

Floral Classification of Honey Using Mid-Infrared Spectroscopy and Surface Acoustic Wave Based z-Nose Sensor

Fourier transform infrared spectroscopy (FTIR) and z-Nose were used as screening tools for the identification and classification of honey from different floral sources. Honey samples were scanned using microattenuated total reflectance spectroscopy in the region of 600-4000 cm(-1). Spectral data were analyzed by principal component analysis, canonical variate analysis, and artificial neural network for classification of the different honey samples from a range of floral sources. Classification accuracy near 100% was achieved for clover (South Dakota), buckwheat (Missouri), basswood (New York), wildflower (Pennsylvania), orange blossom (California), carrot (Louisiana), and alfalfa (California) honey. The same honey samples were also analyzed using a surface acoustic wave based z-Nose technology via a chromatogram and a spectral approach, corrected for time shift and baseline shifts. On the basis of the volatile components of honey, the seven different floral honeys previously mentioned were successfully discriminated using the z-Nose approach. Classification models for FTIR and z-Nose were successfully validated (near 100% correct classification) using 20 samples of unknown honey from various floral sources. The developed FTIR and z-Nose methods were able to detect the floral origin of the seven different honey samples within 2-3 min based on the developed calibrations.

Free amino acid composition and botanical origin of honey

The main amino acids found in 31 Spanish honeys of five different single botanical origins, were proline, phenylalanine, tyrosine and lysine, followed by arginine, glutamic acid, histidine and valine. Principal component analysis explained 64% of the variance with the first three PC variables, the lavender honeys being the only group well differentiated. Although the best grouped honeys were those from orange blossom, overlapping with eucalyptus honeys, on the one hand, and with the indistinguishable group formed by rosemary and thyme honeys, on the other hand, was observed. The Student–Newman–Keuls test allowed the grouping of rosemary, thyme and orange blossom honeys, whereas eucalyptus and lavender honeys showed specific amino acid compositions which made them different when compared with this group and also between themselves. Lavender honeys had the highest concentrations of tyrosine. The results obtained for the former honeys together with those obtained for another set of 17 samples, were used to establish a range for amino acid composition of Spanish honeys.

A scientific note on the specific optical rotation of three honey types from Bulgaria

Honey has the property to rotate the polarization plane of polarized light. This depends largely on types and relative proportions of sugars in honey. Each sugar has a specific effect, and the total optical rotation is dependent on concentration. Floral honeys are laevorotary and honeydew (or adulterated floral) honeys are usually dextrorotary. This is a consequence of the normal preponderance in honey of fructose, which has a negative specific rotation, ([α]D = 92.4°) over glucose ([α]D = + 52.7°) (Battaglini and Bosi, 1973; Ivanov, 1986). The measurement of specific rotation is currently used in Greece, Italy and UK to distinguish blossom and honeydew honeys. In Italy, blossom honeys have negative values of optical rotation, while honeydew honeys have positive ones (Kirkwood et al., 1960; Kirkwood et al., 1961; Sacchi and Bosi, 1963; Battaglini and Bosi, 1973; Piazza et al., 1991; Persano Oddo et al., 1995, 1997). Honeydew honeys are usually somewhat lower in fructose content and contain melezitose (([α]D 20 = + 88.2°) or erlose (([α]D 20 = + 121.8°) (Ivanov, 1986). The aim of the study was to apply the method for determination of the specific optical rotation of bee honey according to the Harmonized Methods of the European Honey Commission (Bogdanov et al., 1997) for multifloral, honeydew and Robinia sp. honeys from Bulgaria. The results of the Bulgarian “off-hand method” (Ivanov, 1986) are different from those obtained from the method used by the European Honey Commission (Bogdanov et al., 1997). For that purpose a comparison of optical measurements of Bulgarian honeys from different origins was carried out with the harmonised method of the European Honey Commission. The specific optical rotation ([α]D), was determined in 29 honeys (Robinia sp. n = 10, multifloral n = 10, honeydew n = 9), produced in 2000, from various regions and different phytogeographical areas in Bulgaria. The specific optical rotation was evaluated by the method of the European Honey Commission (Bogdanov et al., 1997). The botanical origin of the samples (Tab. I) was established by their melissopalynological, organoleptic, physical and chemical characteristics (Louveaux et al., 1978; Persano Oddo et al., 1995). The results from the study on the specific optical rotation, are presented in Table I. It was estimated that the specific optical rotation of the Robinia honeys was (-) 17.0 ± 1.2, which was similar to previously reported values (Piazza et al., 1991; Persano Oddo et al., 1997). The average value of the multifloral honeys was (-) 14.8 ± 4.9, which was similar of the values of multifloral honeys found by Sacchi and Bosi (1963) and to those found in Robinia honeys. The values of the specific optical rotation of the Bulgarian honeydew honeys were positive (4.2 ± 1.3), which is consistent with other results (Kirkwood et al., 1960; Kirkwood et al., 1961; Sacchi and Bosi, 1963; Battaglini and Bosi, 1973; Persano Oddo et al., 1995). However these values were lower than those found in Italian honeydew honeys, which varied from 13.6 to 16.6.

STUDIES ON LIBYAN HONEYS

ABSTRACTTen honey samples representing various floral types were obtained from different areas in Libya. Two other samples were obtained from hives, where bees were fed on sugar syrup and date syrup, respectively. The chemical composition and some characteristics of these samples were studied. The data obtained generally showed that the specifications of honeys produced in Libya conformed with those required for table honey. The application of thin‐layer chromatography on cellulose‐coated plates for the analysis of honey sugars yielded clear resolution and discrete spots. Some measures — such as high level of calcium, low level of potassium and UV‐absorption spectra of honeys were suggested to be used for identifying the sugar‐honeys and for ensuring the quality of blossom honeys. An attempt has been made to predict the granulation behavior of honeys and a derived regression formula was suggested.