Fresh Honey Research Articles

Validação de método para a determinação de 5-hidroximetilfurfural em mel por cromatografia líquida e sua influência na qualidade do produto

In honey 5-hydroxymethyl-2-furaldehyde (HMF) is one of the most typical products of degradation: it is usually absent in fresh honey, but its concentration tends to rise as a result of heating processes or long-term storage. The validation protocol was performed in terms of detection and quantification limits, precision (by repeatability and intermediate precision), linearity and accuracy (by recovery tests). The method has been tested on 15 honey samples of different ages and geographical origin. HMF correlated highly with the age of the samples has been considered a very important parameter to put these honeys on the market or not and/or to estimate their shelf life.

Combined use of HMF and furosine to assess fresh honey quality

AbstractBACKGROUND: The quality of honey can be affected by practices such as adulteration, inadequate storage or the application of severe heat treatments. Because hydroxymehylfurfural (HMF) is an indicator of honey freshness and furosine (ε‐2‐furoylmethyl lysine) has proved to be a useful chemical indicator of the progress of the Maillard reaction in foods, the aim of this work was to assess their usefulness as indicators of fresh honey quality. The effect of heat treatment, storage and adulteration with different types of syrups on HMF and furosine content has been studied.RESULTS: In fresh honey, HMF and furosine values ranged from 0.9 to 14.6 mg kg−1 of product and from 3.06 to 12.06 g kg−1 of protein, respectively. Heating of honey samples with different pH (3.76 and 5.14) produced slight increases in HMF content and negligible changes were detected in furosine values. The storage of fresh honey for 2 years caused a high increase in the HMF level, reaching values above EU limits. However, furosine showed a different behavior depending on the type of honey sample. Adulteration assays using different syrups produced an increase in HMF and a decrease of furosine values by dilution effect. HMF content of adulterated honey samples with syrup of known origin did not exceed EU limits.CONCLUSION: These results show the influence of long periods of storage or adulteration, using different percentages of corn or invert sugar syrups, on HMF and furosine content of fresh honey. This seems to indicate that the combination of HMF and furosine may be useful for evaluating the quality of fresh honey. Copyright © 2009 Society of Chemical Industry

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.

“Metals in Fresh Honeys from Tenerife Island, Spain”

Ashes and contents of Zn, Cu, Fe, Cd and Pb in 140 fresh honey samples from three different areas of Tenerife Island were determined by inductively coupled plasma atomic emission spectrometry and graphite furnace atomic absorption spectrometry. A mean ash content of 0.35% has been determined. The mean Fe, Cu, Zn, Pb and Cd concentrations observed have been 3.37 mg kg(-1), 1.28 mg kg(-1), 2.83 mg kg(-1), 37.33 microg kg(-1), 4.38 microg kg(-1), respectively. A direct statistical correlation has been found between the Fe-Zn and Fe-Pb content, and between the Cd-Zn and Cd-Pb levels.

タイリクヒメハナカメムシの成虫と卵の同時放飼法による定着促進効果

We developed a technique of simultaneously releasing adults and eggs of Orius strigicollis to enhance its early establishment in greenhouses. We first sought suitable oviposition substrates and alternative diets for O. strigicollis adults. Among three species of plants examined as oviposition substrates, the hatchability of eggs was best on Sedum rubrotinctum shoots. Fresh honey was as effective as the eggs of Ephestia kuehniella Zeller, a conventional diet, in increasing the longevity of O. strigicollis adults, indicating that fresh honey can be used as an alternative diet for O. strigicollis. At least one shoot of S. rubrotinctum must be provided per two O. strigicollis females to obtain eggs effectively. About 1,100 eggs were obtained from one bottle of O. strigicollis (Tairiku®, 250 adults) when they were reared with S. rubrotinctum shoots and fresh honey for three days. The number of O. strigicollis offspring found on sweet peppers was increased when eggs of O. strigicollis were released with adults at the same time, suggesting that the simultaneous release of eggs and adults of O. strigicollis was effective in enhancing its early establishment.

Chemical changes in the non-volatile fraction of Brazilian honeys during storage under tropical conditions

The chemical transformations of the non-volatile fraction of Brazilian honeys during storage in tropical condition were monitored. Five systems, namely: 1 – fresh samples; 2 and 3 – samples heated for 3 and 6 months at 35–40 °C; 4 and 5 – samples left under similar conditions to systems 2 and 3, but containing sodium metabisulphite (120 ppm), were tested. The major transformations during storage occurred in the free and lactone acidity, diastase activity and 5-hydroxymethylfurfural (5-HMF) content. Storage modified diastase activity and the content of 5-HMF to an extent that the samples could not remain classified as fresh honey. The action of sodium metabisulphite in the control of the 5-HMF formation seemed to be dependent on other honey characteristics, such as its botanical origin. Sodium metabisulphite also influenced the development of the internal esterification reaction that converts gluconic acid into its corresponding lactone.

The Effects of Nectar–Nicotine on Colony Fitness of Caged Honeybees

Nectar of many bee flowers contains secondary compounds, which are considered toxic for honeybees on repeated exposure. Although many anecdotal reports indicate the toxicity of secondary compounds to bees, only a few studies have tested the extent of toxicity at different honeybee ages, especially at the larval stages. Honeybees encounter nicotine at trace concentrations (between 0.1 and 5 ppm) in floral nectar of a few Nicotiana spp. and in Tilia cordata. Adult honeybee workers tolerate these nicotine concentrations. In controlled nonchoice feeding experiments with caged bees, we investigated the effect of nicotine on hatching success and larval and forager survival. Naturally occurring concentrations of nectar-nicotine did not affect hatching success of larvae or their survival, but the latter was negatively affected by higher concentrations of nicotine (50 ppm). Concentrations of nicotine in fresh honey samples from the hives were 90% lower than the concentrations in the offered experimental sucrose solutions. Our results indicate that honeybees can cope with naturally occurring concentrations of nicotine, without notable mortality, even when consumed in large quantities for more than 3 weeks.

Identification of nitric oxide metabolites in various honeys: effects of intravenous honey on plasma and urinary nitric oxide metabolites concentrations.

Honey has antibacterial activity, promotes healing, and enhances immunity. Its acidity, osmotic effects of its high content of sugar, and hydrogen peroxide are assumed to be responsible for its effects. In this study, various honeys were investigated for the presence of nitrite/nitrate, the stable nitric oxide (NO) metabolites, and the effects of intravenous infusion of honey on urinary and plasma NO end products were studied in healthy sheep. Seven kinds of honey, different in their origin (three from Yemen, two from the United Arab Emirates, one from Germany, and one from India), color, and duration of storage, were investigated for the presence of NO metabolites. The assessment of NO metabolites was performed before and after exposure of the honey samples to heating (80 degrees C for 1 hour) or ultraviolet light (for 24 hours). Seven healthy male sheep were used for the study. Fresh unprocessed yellow honey (2 g/kg of body weight) was infused over a period of 45 minutes to each fasting sheep. Plasma and urinary NO metabolites were measured before and after the infusion. All the honey samples examined had various concentrations of NO metabolites; the highest concentration was in the fresh dark honey collected from Yemen, and the lowest in 1-year-stored dark honey collected from India. Darker or fresh honeys contained more NO metabolites than light or stored honey. After heating, NO metabolites decreased in all the kinds of honey. After ultraviolet exposure, NO metabolites were decreased in four kinds of honey, increased in one kind, and unchanged in two kinds. The darker stored honey had more resistance to heating and ultraviolet exposure. Intravenous infusion of honey elevated urinary NO metabolites from 8.4 +/- 7.4 micromol/L to 14.9 +/- 10 micromol/L during the first 60-90 min after infusion and to 35.2 +/- 34 micromol/L during the next 150-180 min. Plasma NO metabolites were increased during 1, 2, and 3 hours after infusion by 3%, 3.6%, and 17%, respectively. No side effects were reported with the use of intravenous honey. It might be concluded that honey contains various concentrations of NO metabolites. Its intravenous infusion increased plasma and urinary NO metabolites. It is assumed that NO might be responsible, in part, for the biological and therapeutic effects of honey.

R�ckst�nde von Carbendazim und anderen Fungiziden im Bienenhonig aufgrund der Bl�tespritzung von Winterraps

During 2000 to 2002, 91 Hessian spring honeys from regions with an extended cultivation of canola were analysed for residues of the registered fungicides Carbendazim, Iprodion, Metconazol, Tebuconazol and Vinclozolin. The samples included 15 honeys from certified ecological apiaries. While Iprodion and Metconazol were not detected at all and Tebuconazol and Vinclozolin only sporadic with maximum levels of 0,018 mg/kg, Carbendazim was found in 35,2 % of the samples with up to 0,118 mg/kg. The eco honeys did not differ from the other samples. In May 2002 two isolated canola fields (9,8 resp. 5,5 ha) were treated with 11/ha Derosal® (active ingredient: 360 g/l Carbendazim) in 600 l water/ha resp. with 1,5 l/ha Folicur® (active ingredient: 251,2 g/l Tebuconazol) in 400 l water/ha during full blossom while a third field served as an untreated control. Three honey bee colonies were placed close to each field four days before treatment. From each hive, two samples of fresh honey were taken seven days after the treatment and analysed for residues of Carbendazim and Tebuconazol. While only one of six samples from the control field was contaminated with 0,080 mg/kg Carbendazim, each of the six honey samples from the Carbendazim treated field showed residues of Carbendazim (average: 0,145 mg/kg, range: 0,061 - 0,227 mg/kg) and five of six samples from the Tebuconazol treated field were positive for Tebuconazol (average: 0,018 mg/kg, range: < DL- 0,025 mg/kg). Due to its specific characters (slightly hydrophilic compared to other fungicides) a blossom application of Carbendazim can result in extremely high residue levels in honey. In the meantime, the manufacturers of Carbendazim and Thiophanate-methyl acknowledged these findings and, irrespectively of its toxicological relevance, stopped their deal with such products on the German market.

Flavour index and aroma profiles of fresh and processed honeys

AbstractThis paper discusses the importance of flavour profiling in detecting indicative parameters for quality control of fresh and heated honey. Flavour compounds of six unifloral honeys (Lavandula stoechas, Castanea sativa, Dorycnium pentaphyllum, Rosmarinus officinalis, Eucalyptus sp and Robinia pseudoacacia) were investigated. The aroma extracts were obtained by a two‐step procedure involving (i) preliminary steam distillation under reduced pressure to evaluate the methylpyrazines generated in heated honeys by spectrophotometry (flavour index) and (ii) Likens–Nickerson's simultaneous steam distillation and solvent extraction (SDE) method with added NaCl. A combined total of 64 compounds were detected by gas chromatography/mass spectrometry (GC/MS), 58 of which were identified. Some compounds appeared to be characteristic of the floral source, particularly in Spanish lavender (methylated aliphatic acids and aromatic esters), eucalyptus (2,3‐pentanedione, acetoin, 1‐hexyl alcohol, 2‐acetyl‐5‐methylfuran, furfuryl propionate, 2‐phenylacetaldehyde and nerolidol), chestnut (acetophenone and 2‐aminoacetophenone), rosemary and D pentaphyllum (aromatic acids and esters, 2‐phenylacetaldehyde, farnesol and thymol) honeys. Robinia honey samples were characterised by very low levels of aromatic compounds. Twenty‐six flavour compounds were statistically closely related to the floral origin of the honeys (P ≤ 0.05). The flavour index was evaluated progressively in heated honeys, whereas in fresh honeys it showed a minimal value.© 2003 Society of Chemical Industry

Determination of honey quality components by near infrared reflectance spectroscopy

SUMMARYNear infrared reflectance spectroscopy (NIRS) was used to assess the chemical composition of fresh honey samples. Samples (n = 110) from different locations across Uruguay were scanned in transreflectance (0.2 mm path—length) in a NIRS 6500 monochromator in both the visible and near infrared region (400–2500 nm). Prediction equations were developed using modified partial least squares and cross validation was applied to avoid overfitting. Calibrations for water content (g kg−1), pH, electrical conductivity (mS/cm), colour (mm Pfund) and hydroxymethylfurfural (mg kg−1) yielded a coefficient of determination in calibration (R2CAL) and standard error in cross validation of 0.96 (SECV: 31); 0.88 (SECV: 0.21); 0.94 (SECV: 0.07); 0.98 (SECV: 4.7) and 0.67 (SECV: 3.9), respectively. It is concluded that NIRS is a useful method to evaluate chemical composition on fresh honey samples.

Local application of honey for treatment of neonatal postoperative wound infection.

Honey has been described in ancient and modern medicine as being effective in the healing of various infected wounds. In this report we present our experience in nine infants with large, open, infected wounds that failed to heal with conventional treatment. Conventional treatment was defined as having failed if after > or = 14 d of intravenous antibiotic and cleaning the wound with chlorhexidine 0.05% W/V in aqueous solution and fusidic acid ointment the wound was still open, oozing pus, and swab cultures were positive. All infants showed marked clinical improvement after 5 d of treatment with topical application of 5-10 ml of fresh unprocessed honey twice daily. The wounds were closed, clean and sterile in all infants after 21 d of honey application. There were no adverse reactions to the treatment. We conclude that honey is useful in the treatment of post-surgical wounds that are infected and do not respond to conventional systemic and local antibiotic treatment.

Diastase, invertase and β-glucosidase activities in fresh honey from north-west Spain

SUMMARYDiastase (α- and β-amylase), invertase (sucrase or α-glucosidase) and β-glucosidase activities in 46 samples of unheated, commercially purchased Galician (north-west Spain) honeys were determined spectrophotometrically. The honeys were from Eucalyptus sp. (25), Rubus sp. (2) and Castanea sativa (1), or multifloral in origin (18). The mean value for diastase (Gothe scale) was 19.3 ± 6.99 (10.6–38.0), for invertase it was 128.3 ± 31.90 (68.7–225.4) μmoles p-nitrophenyl glycoside hydrolysed/kg honey/min, and for β-glucosidase it was 110.8 ± 19.89 (80.3–176.4) μmoles p-nitrophenyl glycoside hydrolysed/kg honey/min. Correlationships were found between invertase and diastase activities (r = 0.878) and between invertase and β-glucosidase activities (r = 0.871). Comparisons between these values and those obtained by other authors are discussed.

Alberta honey composition

Fresh honeys from the province of Alberta, Canada, were removed by filtration and stored frozen until analysis for moisture, enzymes (α- and β-glucosidase, diastase), 5-(hydroxymethyl)-2-furaldehyde, proline, free and lactone acidity, ash and carbohydrate composition to establish original values for authentic Alberta honey. These samples were found to meet all major national and international honey specifications. Generally, the samples were lower in moisture, α-glucosidase, proline, acidity and ash than many world floral honeys. Proline levels were often lower than 200 ppm which has incorrectly been used as a minimum level for honey authenticity by some honey importers. Fructose-to-glucose ratios were very consistent and averaged 1·09. All samples contained turanose and/or palatinose, and maltose in significant (averaging 1·6%) quantities.

The fluoride content of Finnish honey

The content of fluoride was determined with an ion-specific electrode on 59 samples of honey from 47 localities in Finland. The concentrations ranged from 25 to 550/µg/kg and the mean for all the localities was 85.7 µg F-/kg fresh weight honey. The concentrations were lowest in eastern and northern Finland, where the amount of fluoride in the soil is small, and higher on the coast and areas where more fluoride occurs in the groundwater and bedrock. However, the highest levels of fluoride in honey were detected in the vicinity of Helsinki and some other places where the amount in the groundwater is not especially high. The higher levels in some honey may be due to fluorides introduced into the environment by the activity of man. The effects of fluoride on human health are discussed.

Diastase (α- and β-Amylase) and α-Glucosidase (Sucrase) Activity in Western Canadian Honeys

Forty-five different honeys obtained from the Western Canadian region were examined for α-glucosidase and diastase activity. Fresh honeys varied from 11.3 to 27.5 sucrose converted/100g honey/h (mean, 18.6±4.4) for α-glucosidase activity and 9.6 to 20.7g starch hydrolysed/100g honey/h (mean, 14.3±3.4) for diastase activity. Stored raw and processed honeys had dramatically reduced α-glucosidase activity, but only moderately reduced diastase activity. The best measure for honey freshness seemed to be the ratio of α-glucosidase activity to diastase activity, which varied between 1.18 and 1.57 (mean, 1.31±0.13) for fresh honeys, while older honeys had significantly lower values.

The Effect of Acid-Hydrolysed Sucrose on Honeybees

SUMMARYSucrose, or starch, hydrolysed with mineral or organic acids is toxic for honeybees, whereas sucrose hydrolysed with invertase is not. The best-known products of the action of acids on hexoses, 5-hydroxymethylfuraldehyde (HMF), laevulinic acid and formic acid were similarly toxic to bees when fed to them, but only if more concentrated than in acid-hydrolysed sucrose. Neither the acids used to hydrolyse the carbohydrates, nor the salts formed by neutralizing them, were toxic, so unknown products of acid hydrolysis must cause most of the harm to bees. Heated honey or old honey was less suitable for bees than fresh honey or sucrose; their suitability was inversely correlated with the concentration in them of HMF, but this was too small to cause the harm observed. Evidently substances that are more toxic than HMF must accumulate along with it in heated honey; these may be similar to those in acid-hydrolysed carbohydrates. Bees fed acid-hydrolysed carbohydrates developed ‘dysentery’ before they died, possibly because essential solutes and water were lost from the body into the rectum, the contents of which were doubled, but only slightly diluted.

Feeding behaviour of adults of Pieris brassicae (L.) in a laboratory culture

SummaryOnly a few individuals in the first generation of adults of Pieris brassicae (L.) reared in captivity will feed on artificially prepared flowers. By breeding from the eggs laid by these individuals and from a few others which have been helped to feed it is possible to maintain the stock. In each successive generation a few more individuals feed, and after about four generations most of the insects feed voluntarily. Finally, after many generations, all the insects use the flowers, and the experiments described are concerned with this adapted stock.Many factors influence the attraction of the insects to the artificial flowers and the volume of food taken. Colour, blue or yellow, is responsible for attracting the adults to the flowers, and it is only when they are very close to the flowers and under the stimulus of colour that they show any detectable reaction to the odour of the honey solution in the flowers. Larger blue flowers are more attractive than smaller blue flowers.The insects find the artificial flowers more easily, at first, if they are high in the cage. More honey solution is taken at 30 than at 20°C. and more in a large cage than in a small cage. When given a choice, the insects take more 10 per cent, (v/v) than 1 per cent, (v/v) honey solution and more 20 per cent, (v/v) solution than 10 per cent, (v/v) solution. When offered two of these solutions in separate cages the insects at first take less of the 1 per cent, solution than of the 10 per cent, solution. Later, presumably in an effort to obtain sufficient nutriment, they take more of the weaker solution than of the stronger solution. The insects live for a much shorter time on the 1 per cent, solution than on the 10 per cent, solution. Fresh honey solution is preferred to a solution 4–5 days old, and older honey solution is quite unsuitable as food. When the survival of adults fed on honey and sucrose solution is compared it is found that females, especially, survive longer when feeding on honey.About 50 per cent, of the adults fed on 10 per cent, honey solution in the normal stock cage under glasshouse conditions live for 18 days. Very few survive for longer than 36 days. Starved insects all die by the llth day under similar conditions. When starved at 12·5°C. and 60 per cent, relative humidity, about half the males live for 17 to 19 days, but all are dead by about the 23rd day, whereas half the females live for about 29 days and some survive up to 40 days.