Pyrrolizidine alkaloids in honey: comparison of analytical methods

Pyrrolizidine alkaloids (PAs) are a structurally diverse group of toxicologically relevant secondary plant metabolites. Currently, two analytical methods are used to determine PA content in honey. To achieve reasonably high sensitivity and selectivity, mass spectrometry detection is demanded. One method is an HPLC-ESI-MS-MS approach, the other a sum parameter method utilising HRGC-EI-MS operated in the selected ion monitoring mode (SIM). To date, no fully validated or standardised method exists to measure the PA content in honey. To establish an LC-MS method, several hundred standard pollen analysis results of raw honey were analysed. Possible PA plants were identified and typical commercially available marker PA-N-oxides (PANOs). Three distinct honey sets were analysed with both methods. Set A consisted of pure Echium honey (61-80% Echium pollen). Echium is an attractive bee plant. It is quite common in all temperate zones worldwide and is one of the major reasons for PA contamination in honey. Although only echimidine/echimidine-N-oxide were available as reference for the LC-MS target approach, the results for both analytical techniques matched very well (n = 8; PA content ranging from 311 to 520 μg kg(-1)). The second batch (B) consisted of a set of randomly picked raw honeys, mostly originating from Eupatorium spp. (0-15%), another common PA plant, usually characterised by the occurrence of lycopsamine-type PA. Again, the results showed good consistency in terms of PA-positive samples and quantification results (n = 8; ranging from 0 to 625 μg kg(-1) retronecine equivalents). The last set (C) was obtained by consciously placing beehives in areas with a high abundance of Jacobaea vulgaris (ragwort) from the Veluwe region (the Netherlands). J. vulgaris increasingly invades countrysides in Central Europe, especially areas with reduced farming or sites with natural restorations. Honey from two seasons (2007 and 2008) was sampled. While only trace amounts of ragwort pollen were detected (0-6.3%), in some cases extremely high PA values were detected (n = 31; ranging from 0 to 13019 μg kg(-1), average = 1261 or 76 μg kg(-1) for GC-MS and LC-MS, respectively). Here the results showed significantly different quantification results. The GC-MS sum parameter showed in average higher values (on average differing by a factor 17). The main reason for the discrepancy is most likely the incomplete coverage of the J. vulgaris PA pattern. Major J. vulgaris PAs like jacobine-type PAs or erucifoline/acetylerucifoline were not available as reference compounds for the LC-MS target approach. Based on the direct comparison, both methods are considered from various perspectives and the respective individual strengths and weaknesses for each method are presented in detail.     

Pyrrolizidine alkaloids in floral honeys of tropical Ghana: a health risk assessment

ABSTRACT

There is a vast amount of information about the nutritional and medicinal properties of honey as a result of its numerous benefits. However, honeys have been found to be contaminated with hepatotoxic and carcinogenic pyrrolizidine alkaloids (PAs) on account of bees foraging on PA-containing plants. This study deals with the analysis of PAs in tropical honeys emanating from different agro-ecological zones of Ghana in order to assess its potential health risk. PAs of 48 honey samples were analysed using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The results show that a total of 85% of the honeys from various agro-ecological zones were PA positive including all honeys from supermarkets. The highest concentration of PAs was 2639 μg kg^?1, while the average PA concentration of the samples was 283 μg kg^?1. The study also found Chromolaena odorata pollens in majority of the honeys, thus indicating the plant as major source of PA contamination of honeys in the tropical regions.     

Pyrrolizidine alkaloids in food: downstream contamination in the food chain caused by honey and pollen

In recent years, there has been a steadily growing number of published data on pyrrolizidine alkaloids (PAs) in honey and pollen. This raises the question whether honey and/or pollen used as ingredients in food processing might provoke a downstream contamination in the food chain. Here we addressed two different facets in connection with PAs in honey and pollen. First, we analysed the PA content of several food types such as mead (n = 19), candy (n = 10), fennel honey (n = 9), soft drinks (n = 5), power bars and cereals (n = 7), jelly babies (n = 3), baby food (n = 3), supplements (n = 3) and fruit sauce (n = 1) that contained honey as an ingredient in the range of 5% to approximately 37%. Eight out of 60 retail samples were tested as being PA-positive, corresponding to 13%. Positive samples were found in mead, candy and fennel honey, and the average PA content was calculated to be 0.10 μg g(-1) retronecine equivalents (ranging from 0.010 to 0.484 μg g(-1)). Furthermore, we investigated the question whether and how PAs from PA pollen are transferred from pollen into honey. We conducted model experiments with floral pollen of Senecio vernalis and PA free honey and tested the influence of the quantity of PA pollen, contact time and a simulated honey filtration on the final PA content of honey. It could clearly be demonstrated that the PA content of honey was directly proportional to the amount of PA pollen in honey and that the transfer of PAs from pollen to honey was a rather quick process. Consequently, PA pollen represents a major source for the observed PA content in honey. On the other hand, a good portion remains in the pollen. This fraction is not detected by the common analytical methods, but will be ingested, and it represents an unknown amount of 'hidden' PAs. In addition, the results showed that a technically and legally possible honey filtration (including the removal of all pollen) would not be an option to reduce the PA level of the final product significantly.     

Pyrrolizidine alkaloids: their occurrence in Spanish honey collected from purple viper’s bugloss (Echium spp.)

The incidence and concentration of pyrrolizidine alkaloids (PAs) from Echium spp. plant have been defined in 103 Spanish honey samples. Each sample was examined to determine total pollen content, the percentage of Echium spp. pollen, and simultaneous measurements of PAs and their N-oxides concentrations by the HPLC-ESI/MS method to identify the potential origin of PAs in honey. PAs were found in 94.2% of the raw honey samples analysed, in the range of 1–237 µg kg^?1 (average concentration = 48 µg kg^?1). The PA pattern was clearly dominated by echimidine, lycopsamine and their N-oxides, representing the 97.8% of total ∑PAs, and only echimidine and echimidine-N-oxide surpassed the 87% of total ∑PA content. Others PAs, seneciphylline and heliotrine-N-oxide, appear to be reported in a lower incidence and concentration (average of 3 and 1 µg kg^?1, respectively). The Pearson Chi-squared test (p ≤ 0.01) confirms the non-correspondence between pollen plants and PA content. This study was also realised to generate a dataset in order to evaluate the potential risk of Spanish honeys containing PA plants belonging to the genera Echium.     

Pyrrolizidine alkaloids in food: downstream contamination in the food chain caused by honey and pollen

In recent years, there has been a steadily growing number of published data on pyrrolizidine alkaloids (PAs) in honey and pollen. This raises the question whether honey and/or pollen used as ingredients in food processing might provoke a downstream contamination in the food chain. Here we addressed two different facets in connection with PAs in honey and pollen. First, we analysed the PA content of several food types such as mead (n?=?19), candy (n?=?10), fennel honey (n?=?9), soft drinks (n?=?5), power bars and cereals (n?=?7), jelly babies (n?=?3), baby food (n?=?3), supplements (n?=?3) and fruit sauce (n?=?1) that contained honey as an ingredient in the range of 5% to approximately 37%. Eight out of 60 retail samples were tested as being PA-positive, corresponding to 13%. Positive samples were found in mead, candy and fennel honey, and the average PA content was calculated to be 0.10?µg?g^–1 retronecine equivalents (ranging from 0.010 to 0.484?µg?g^–1). Furthermore, we investigated the question whether and how PAs from PA pollen are transferred from pollen into honey. We conducted model experiments with floral pollen of Senecio vernalis and PA free honey and tested the influence of the quantity of PA pollen, contact time and a simulated honey filtration on the final PA content of honey. It could clearly be demonstrated that the PA content of honey was directly proportional to the amount of PA pollen in honey and that the transfer of PAs from pollen to honey was a rather quick process. Consequently, PA pollen represents a major source for the observed PA content in honey. On the other hand, a good portion remains in the pollen. This fraction is not detected by the common analytical methods, but will be ingested, and it represents an unknown amount of ‘hidden’ PAs. In addition, the results showed that a technically and legally possible honey filtration (including the removal of all pollen) would not be an option to reduce the PA level of the final product significantly.     

Physico-chemical properties,composition and pollen spectrum of french lavender (Lavandula stoechas L.) honey produced in Spain

The palynological and physico-chemical properties of 26 samples of French lavender (Lavandula stoechas) honey commercially produced in Spain have been defined. Each sample was examined to determine the total pollen content, percentage ofL. stoechas pollen and pollen spectrum. On the basis of the honey pollen analysis, 14 samples were excluded as they were of different botanical origin (Echium spp.). In total 67 different pollen types were identified. The sugar spectrum showed low percentages of trisaccharides and sucrose. The enzymatic activity was lower than that found in other unifloral Spanish honeys. A minimum of 10%L. stoechas pollen and maximum of 30%Echium sp. pollen are the suggested requirements to characterize this honey.     

Jakobs-Kreuzkraut (<Emphasis Type="Italic">Senecio jacobaea</Emphasis>): eine Ursache für Pyrrolizidin-Alkaloide im Sommerhonig?

Pyrrolizidine alkaloids (PAs) are secondary plant compounds, which may be carried into honey by honey bees (Apis mellifera) and thus enter the human food chain. Depending on the quantity consumed, PAs are considered harmful to human health. At present, however, there is no statutory limit for PAs in foodstuffs. Because of several hints that larger occurrences of PA-containing tansy ragwort (Senecio jacobaea) may be responsible for PAs in summer honeys, honey samples from regions with and without tansy ragwort from all across Schleswig-Holstein were tested for their PA content (28 individual PAs) by LC-MS/MS analysis in 2014. By including honey samples from surroundings of flower plots established on arable land, it was tested if the carry-over of PAs into honey can be reduced by “distraction feed”. Samples from regions with tansy ragwort showed significantly higher PA contents than those from regions without tansy ragwort. Flower plots had no significant influence on the PA content. PAs were detected in 53.5 % of the 86 honey samples investigated. The mean PA value of PA-positive honeys was much higher than the median value since the sample comprised only few high and many low values. 28.6 % of the detected PAs were not from Senecio species, but from the Borage family (Boraginaceae) or Hemp Agrimony (Eupatorium cannabinum). In 2.3–15.1 % of the samples the limit value recommended by the BfR (Analytik und Toxizität von Pyrrolizidinalkaloiden sowie eine Einschätzung des gesundheitlichen Risikos durch deren Vorkommen in Honig. Stellungnahme Nr. 038/2011 des BfR vom 11. August 2011, ergänzt am 21. Januar 2013. Bundesinstitut für Risikobewertung [Hrsg.], Berlin: 37 S, 2013a) for different eating habits was exceeded. Because of the potential risk to human health, beekeepers and users of land with larger occurrences of tansy ragwort should take joint measures to keep the PA load in summer honeys as low as possible.     

Pyrrolizidine alkaloids in honey: risk analysis by gas chromatography-mass spectrometry

Recently, contamination of honey with pyrrolizidine alkaloids (PA) has been reported as potential health risk. Therefore, it was of interest to develop a reliable tool for selective and quantitative determination of PA in honey. Sample preparation of the novel method comprises strong cation exchange SPE (SCX-SPE), followed by two reduction steps using zinc and LiAlH(4), as well as subsequent silylation. During this procedure the separated PA are converted into the necin backbone, the common structural feature of PA toxicity, which is analyzed by GC-MS in the SIM mode. The procedure was validated using PA from extracts of Senecio vernalis as well as authentic PA standards including their corresponding N-oxides. The PA content of honey samples was quantified with heliotrine as internal standard. The method was applied to generate a dataset in order to evaluate the potential risk of PA contamination especially for retail honeys available on the German/European market. No selection criteria in terms of floral or geographical origin were applied on the samples before analysis. In total, 216 commercially available floral honey samples were analyzed. Among them 19 samples contained PA, in the range of 0.019-0.120 microg/g, calculated as retronecine equivalents. The reported method facilitates the selective determination of PA without the need to identify each individual PA independently. The PA contamination of honey is expressed in terms of a single sum parameter and no background information such as foraged plants and pollen analysis is necessary. The LOQ is 0.01 ppm with a S/N of 7:1.     

Quantification of pyrrolizidine alkaloids in North American plants and honey by LC-MS: single laboratory validation

Pyrrolizidine alkaloids (PAs) are a class of naturally occurring compounds produced by many flowering plants around the World. Their presence as contaminants in food systems has become a significant concern in recent years. For example, PAs are often found as contaminants in honey through pollen transfer. A validated method was developed for the quantification of four pyrrolizidine alkaloids and one pyrrolizidine alkaloid N-oxide in plants and honey grown and produced in British Columbia. The method was optimised for extraction efficiency from the plant materials and then subjected to a single-laboratory validation to assess repeatability, accuracy, selectivity, LOD, LOQ and method linearity. The PA content in plants ranged from1.0 to 307.8 µg/g with repeatability precision between 3.8 and 20.8% RSD. HorRat values were within acceptable limits and ranged from 0.62 to 1.63 for plant material and 0.56–1.82 for honey samples. Method accuracy was determined through spike studies with recoveries ranging from 84.6 to 108.2% from the raw material negative control and from 82.1–106.0 % for the pyrrolizidine alkaloids in corn syrup. Based on the findings in this single-laboratory validation, this method is suitable for the quantitation of lycopsamine, senecionine, senecionine N-oxide, heliosupine and echimidine in common comfrey (Symphytum officinale), tansy ragwort (Senecio jacobaea), blueweed (Echium vulgare) and hound’s tongue (Cynoglossum officinale) and for PA quantitation in honey and found that PA contaminants were present at low levels in BC honey.     

Detection of pyrrolizidine alkaloids in commercial honey using liquid chromatography–ion trap mass spectrometry

Pyrrolizidine alkaloids (PAs) are known secondary plant metabolites which can cause hepatotoxicity in both humans and livestock. PAs can be consumed through the use of plants for food, medicinal purposes and as contaminants of agricultural crops and food. PA contaminated grain has posed the largest health risk, although any PA contamination in our food chain should be recognised as a potential health threat. For this purpose, retail honeys were tested by LC–MS/MS. The method allows for specific identification of toxic retronecine and otonecine-type PAs by comparison to reference compounds via a spectral library. In total, 50 honey samples were matched to the reference spectra within a set of tolerance parameters. Accurate data analysis and quick detection of positive samples was possible. Positive samples contained an average PA concentration of 1260 μg kg^?1 of honey. Good linear calibrations were obtained (R² > 0.991). LOD and LOQ ranged from 0.0134 to 0.0305 and 0.0446 to 0.1018 μg mL^?1, respectively.     

Uncertainties in the determination of pyrrolizidine alkaloid levels in naturally contaminated honeys and comparison of results obtained by different analytical approaches

The contamination of honey with hepatotoxic pyrrolizidine alkaloids (PAs) is a well-known hazard for food safety. While management strategies and controls of the honey industry aim to reduce the PA levels, uncertainties remain with regard to the safety of regionally produced and marketed honey. In addition, a previous study showed large differences of results obtained after various periods of storage and apparent differences between the analytical results of different laboratories. Therefore, this study aimed at examining these uncertainties by monitoring the impact of storage on the PA and PA N-oxide (PANO) content of two freshly harvested honeys and on possible demixing effects caused by pollen settling. Additionally, three analytical approaches – target analysis with matrix-matched calibration or standard addition and a sum parameter method – were applied for a comparative analysis of 20 honeys harvested in summer 2016. All samples originated from Schleswig-Holstein in Northern Germany where the PA plant Jacobaea vulgaris is currently observed on a massive scale. The results of the time series analyses showed that PANO levels markedly decreased within a few weeks and practically reached the LOD 16 weeks after harvest. Tertiary PAs, by contrast, remained stable and did not increase as a consequence of PANO decrease. The experiments on a putative demixing, which may result in a heterogeneous distribution of PAs/PANOs, revealed that there was no such effect during storage of up to 12 weeks. A comparison of the PA/PANO levels obtained by different analytical approaches showed that in some cases the sum parameter method yielded much higher levels than the target approaches, whereas in other cases, the target analysis with standard addition found higher levels than the other two methods. In summary, the results of this study highlight uncertainties regarding the validity and comparability of analytical results and consequently regarding health risk assessment.     

Pyrrolizidine alkaloids in honey: comparison of analytical methods

Pyrrolizidine alkaloids (PAs) are a structurally diverse group of toxicologically relevant secondary plant metabolites. Currently, two analytical methods are used to determine PA content in honey. To achieve reasonably high sensitivity and selectivity, mass spectrometry detection is demanded. One method is an HPLC-ESI-MS-MS approach, the other a sum parameter method utilising HRGC-EI-MS operated in the selected ion monitoring mode (SIM). To date, no fully validated or standardised method exists to measure the PA content in honey. To establish an LC-MS method, several hundred standard pollen analysis results of raw honey were analysed. Possible PA plants were identified and typical commercially available marker PA-N-oxides (PANOs). Three distinct honey sets were analysed with both methods. Set A consisted of pure Echium honey (61–80% Echium pollen). Echium is an attractive bee plant. It is quite common in all temperate zones worldwide and is one of the major reasons for PA contamination in honey. Although only echimidine/echimidine-N-oxide were available as reference for the LC-MS target approach, the results for both analytical techniques matched very well (n?=?8; PA content ranging from 311 to 520?µg?kg^?1). The second batch (B) consisted of a set of randomly picked raw honeys, mostly originating from Eupatorium spp. (0–15%), another common PA plant, usually characterised by the occurrence of lycopsamine-type PA. Again, the results showed good consistency in terms of PA-positive samples and quantification results (n?=?8; ranging from 0 to 625?µg?kg^?1 retronecine equivalents). The last set (C) was obtained by consciously placing beehives in areas with a high abundance of Jacobaea vulgaris (ragwort) from the Veluwe region (the Netherlands). J. vulgaris increasingly invades countrysides in Central Europe, especially areas with reduced farming or sites with natural restorations. Honey from two seasons (2007 and 2008) was sampled. While only trace amounts of ragwort pollen were detected (0–6.3%), in some cases extremely high PA values were detected (n?=?31; ranging from 0 to 13019?µg?kg^?1, average?=?1261 or 76?µg?kg^?1 for GC-MS and LC-MS, respectively). Here the results showed significantly different quantification results. The GC-MS sum parameter showed in average higher values (on average differing by a factor 17). The main reason for the discrepancy is most likely the incomplete coverage of the J. vulgaris PA pattern. Major J. vulgaris PAs like jacobine-type PAs or erucifoline/acetylerucifoline were not available as reference compounds for the LC-MS target approach. Based on the direct comparison, both methods are considered from various perspectives and the respective individual strengths and weaknesses for each method are presented in detail.     

Physicochemical attributes and pollen spectrum of Portuguese heather honeys

The qualities of selected honey samples of “Serra da Lousã” (Portugal) from three consecutive harvests (20 samples from each harvest) were evaluated by determing the pollen spectrum and physicochemical attributes. The following determinations were carried out: moisture, electrical conductivity, hydroxymethylfurfural, diastase activity, pH, acidity (free, lactone and total), formol number, reducing sugars, apparent sucrose, insoluble material and ash. The samples were found to meet all major national and international honey specifications. Honeys were considered to be monofloral whenever the dominant pollen was found to be over 45% of total pollen. From the 60 studied samples, 70% were monofloral honeys from Erica sp., 17% monofloral honeys from Ericaceae (Erica sp. and Calluna vulgaris (L.) Hull) and 13% multifloral honeys with a high percentage of Erica sp.     

Unifloral honeys of the province of Buenos Aires,Argentine

Samples of 63 unifloral honeys of the province of Buenos Aires, Argentina, from Eucalyptus spp, Lotus spp, Helianthus annuus, Melilotus albus, Brassicaceae, clovers other than Lotus and Melilotus, and Sagittaria montevidensis, were obtained by cold extraction at the laboratory. The frequencies of occurrence of pollen types, and the moisture, hydroxymethylfurfural, ash, acidity and proline contents were determined. Electrical conductivity, pH and colour were also analysed. Honey presented a high percentage (about 40%) of unifloral honey. The most frequent unifloral honeys were from Eucalyptus spp, Lotus spp and Helianthus annuus. Samples had a low pollen diversity with six to 19 pollen types, the most important nectariferous taxa being those that characterized the unifloral honeys. All samples presented moisture, hydroxymethylfurfural, ash and free acidity contents according to international standards. The colour of the honey was from water white to light amber, and all samples had a very low ash content. Significant differences at the 5% level in the hydroxymethylfurfural content, electrical conductivity, colour and proline content were observed among honeys from different floral origins. However, a high variability between samples from the same floral origin was observed, indicating that other factors such as accompanying pollen and geographical origin affect the physicochemical characteristics of honey. Copyright © 2005 Society of Chemical Industry     

Total amitraz residues in bee honeys]

A total of 330 bee honey samples was analysed in 1986-1990, and the results are reported. Analysis was performed according to the method for the amitraz total residue determination by hydrolysis and steam distillation as described. 60% of the honeys were practically not contamined (total residue content amounting to 0.01 mg/kg), 8.5% of the honeys contained more than 0.05 mg/kg. Maximal values of 0.2-0.5 mg/kg were stated. 54% of the rape-honeys contained more than 0.01 mg/kg, 19% more than 0.05 mg/kg.     

Chemical fingerprinting identifies Echium vulgare,Eupatorium cannabinum and Senecio spp. as plant species mainly responsible for pyrrolizidine alkaloids in bee-collected pollen

Various studies have shown that bee-collected pollen sold as nutritional supplements may contain toxic pyrrolizidine alkaloids (PAs) and, thus, pose a potential health risk for consumers. The level of contamination may vary according to its geographical and botanical origin. Here, the PA content of pollen produced in Switzerland was studied and 32 commercially available bee-collected pollen supplements produced between 2010 and 2014 were analysed. In addition, at what time period bees collect PA-containing pollen was investigated. Hence, this study looked into the occurrence of PAs in pollen samples collected daily during two-to-three consecutive seasons. Furthermore, the PA spectrum in pollen was compared to the spectrum found in flower heads of PA-plants to unambiguously identify plants responsible for PA contamination of pollen. The PA concentration of commercial and daily collected pollen was determined by target analysis using an HPLC-MS/MS system, allowing the detection of 18 different PAs and PA N-oxides found in the genera Echium, Eupatorium and Senecio, while the comparison of the PA spectrum in pollen and flower heads was performed by LC-HR-MS, allowing the detection of all PA types in a sample, including saturated, non-carcinogenic PAs. Of the commercially available pollen, 31% contained PAs with a mean concentration of 319 ng/g, mainly Echium- and Eupatorium-type PAs, while the PA concentrations were below the limit of quantitation (LOQ) in 69% of the pollen samples. Bees collected pollen containing Echium-type PAs mainly in June and July, while they gathered pollen containing Eupatorium-type PAs from mid-July to August. Senecio-type PAs appeared from June to September. Comparison of the PA array in pollen and plants identified E. vulgare and E. cannabinum as the main plants responsible for PA contamination of Swiss bee-collected pollen, and to a lesser extent also identified plants belonging to the genus Senecio.     

HPLC-fluorimetric method for analysis of amino acids in products of the hive (honey and bee-pollen)

An optimization of the OPA method has made feasible separation and quantification of 23 amino acids, which include 5 infrequently searched for. Detection limits ranged from 0.24 to 10.1 pmol in honey and from 29.1 to 0.42 pmol in bee-pollen; reproducibility (C.V.) ranged from 5.3% to 20.4%; recoveries were above 78.8%. Forty monovarietal honey samples from ilex, oak, heather and chestnut-tree were analyzed for their free amino acid profiles. α-Aminoadipic acid and homoserine are reported for the first time in honeys. Thirty-two samples of Spanish bee-pollen, made of a majority of pellets from Cistus Ladanifer (67.1%) and Echium plantagineum (8.9%), were analyzed for their free and total amino acid profiles. Free γ-aminobutyric acid was extensively found with an average of 0.53 mg/g, while Hser and Orn were infrequent. Manually separated monofloral pellets from Cistus ladanifer and Echium plantagineum were analyzed for their free amino acid contents (including proline): 32.46 and 21.87 mg/g for the former and 22.18 and 12.23 mg/g for the latter. In contrast, the total amino acid percentage (on a dry weight basis) was 13.95% for Cistus ladanifer and 32.22% for Echium plantagineum.     

Physico-chemical properties, composition and pollen spectrum of french lavender (Lavandula stoechas L.) honey produced in Spain

The palynological and physico-chemical properties of 26 samples of French lavender (Lavandula stoechas) honey commercially produced in Spain have been defined. Each sample was examined to determine the total pollen content, percentage ofL. stoechas pollen and pollen spectrum. On the basis of the honey pollen analysis, 14 samples were excluded as they were of different botanical origin (Echium spp.). In total 67 different pollen types were identified. The sugar spectrum showed low percentages of trisaccharides and sucrose. The enzymatic activity was lower than that found in other unifloral Spanish honeys. A minimum of 10%L. stoechas pollen and maximum of 30%Echium sp. pollen are the suggested requirements to characterize this honey.

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Zusammensetzung, physikalisch-chemische Eigenschaften und Pollenspektrum im spanischen Heidehonig (Lavandula stoechas L.)

Zusammenfassung Anhand von 26 Stichproben wurden die physikalisch-chemischen Eigenschaften und das Pollen-Spektrum des kommerziell vertriebenen spanischen Heidehonigs (Lavandula stoechas L.) bestimmt. Jede Stichprobe wurde auf den Gesamtgehalt an Pollen sowie den prozentualen Anteil an Pollen desL. stoechas und auf das Pollen-Spektrum untersucht. Aufgrund der Analyse des Melissen-Spektrums mußten 14 Stichproben ausgeschlossen werden, da sie unterschiedlichen botanischen Ursprungs waren (Echium spp.). Es wurden 67 verschiedene Pollenarten identifiziert. Das Zuckerspektrum wies einen geringen Anteil an Trisacchariden und Sucrose auf. Die enzymatische Aktivität dieser Honigarten war geringer bei anderen Blütenpflanzen. Als Mindestmenge an Pollen desL. stoechas werden 10% vorgeschlagen, und ein Pollenanteil von <30% beiEchium sp. ist für diesen Honig charakteristisch.

     

Multi-elemental composition and physical properties of honey samples from Malaysia

The elemental profiles of six honey samples from Malaysia had been constructed using the data obtained from both ICP-AES and ICP-MS. Potassium and sodium were the most abundant minerals covering from 69.3-78.6% and 14.1-28.7%, respectively. The ratio of potassium to sodium was more than one. Even though the minerals and trace elements composition varied dependent on the type of honey samples, there was no statistically significant difference between the analysed honey samples, namely tualang, gelam, acacia and a few forest honeys based on two-factor ANOVA and cluster analysis. The total element content of honey samples were strongly correlated with the electrical conductivity, but only have moderate correlation with the ash content and honey colour based on the regression analysis. PCA result on the available elemental data from worldwide honeys, including honey samples from Malaysia revealed that potassium and sodium were the mineral markers to distinguish honey origin. Both tualang and gelam honey samples from Malaysia have close mineral profile with sesame honeys from Egypt and multifloral honeys from India, whereas forest honeys Malaysia were near to avocado honeys from Spain and multifloral honeys from India.     

Crystal Control In Processed Liquid Honey

Liquid processed honeys produced in the province of Alberta, Canada, were studied to identify controllable factors to delay glucose crystallization. Individual producer honeys were analyzed for glucose and fructose using a new HPLC procedure. Selective use of producer honeys for liquid processed honey was of no advantage since the samples were all supersaturated in glucose (>30% glucose) and contained unexpectedly consistent fructose/glucose ratios of about 1.12. Crystallization could be delayed by filling retail containers at 45 °C or above. Moisture losses noted at well over 1% a year in plastic containers could also contribute to an increase in crystallization for stored honey.